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  • 301.
    Alizadeh Khameneh, Mohammad Amin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Eshagh, Mehdi
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. University West, Division of Surveying Engineering.
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Optimisation of Lilla Edet Landslide GPS Monitoring Network2015In: Journal of Geodetic Science, ISSN 2081-9919, E-ISSN 2081-9943, Vol. 5, no 1, p. 57-66Article in journal (Refereed)
    Abstract [en]

    Since the year 2000, some periodic investigations have been performed in the Lilla Edet region to monitor and possibly determine the landslide of the area with the GPS measurements. The responsible consultant has conducted this project by setting up some stable stations for GPS receivers in the risky areas of Lilla Edet and measured the independent baselines amongst the stations according to their observation plan. Here, we optimise the existing surveying network and determine the optimal configuration of the observation plan based on different criteria. We aim to optimise the current network to become sensitive to detect 5 mm possible displacements in each net point. The network quality criteria of precision, reliability and cost are used as object functions to perform single-, bi- and multi-objective optimisation models. It has been shown in the results that the single-objective model of reliability, which is constrained to the precision, provides much higher precision than the defined criterion by preserving almost all of the observations. However, in this study, the multi-objective model can fulfil all the mentioned quality criteria of the network by 17% less measurements than the original observation plan, meaning 17% of saving time, cost and effort in the project.

  • 302.
    Alizadeh Khameneh, Mohammad Amin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Eshagh, Mehdi
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. Department of Engineering Science, University West, Trollhättan, Sweden.
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    The Effect of Instrumental Precision on Optimisation of Displacement Monitoring Networks2016In: Acta Geodaetica et Geophysica, ISSN 2213-5820, Vol. 51, no 4, p. 761-772Article in journal (Refereed)
    Abstract [en]

    In order to detect the geo-hazards, different deformation monitoring networks are usually established. It is of importance to design an optimal monitoring network to fulfil the requested precision and reliability of the network. Generally, the same observation plan is considered during different time intervals (epochs of observation). Here, we investigate the case that instrumental improvements in sense of precision are used in two successive epochs. As a case study, we perform the optimisation procedure on a GPS monitoring network around the Lilla Edet village in the southwest of Sweden. The network was designed for studying possible displacements caused by landslides. The numerical results show that the optimisation procedure yields an observation plan with significantly fewer baselines in the latter epoch, which leads to saving time and cost in the project. The precision improvement in the second epoch is tested in several steps for the Lilla Edet network. For instance, assuming two times better observation precision in the second epoch decreases the number of baselines from 215 in the first epoch to 143 in the second one.

  • 303.
    Alizadeh Khameneh, Mohammad Amin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. WSP Civils, Department of Geographic Information and Asset Management.
    Horemuž, Milan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Jensen, Anna B. O.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Vium Andersson, Johan
    WSP Civils, Department of Geographic Information and Asset Management.
    Optimal Vertical Placement of Total Station2018In: Journal of Surveying Engineering, ISSN 0733-9453, E-ISSN 1943-5428Article in journal (Refereed)
    Abstract [en]

    When using the free station method, a Total Station (TS) is established by performing distance and angle observations toward a number of Control Points (CPs). The quality of the establishment is crucial for the quality of subsequent measurements. The optimal horizontal location of the TS has been investigated in previous studies. Even the vertical precision is important in many applications, especially with significant height variations. Therefore in this paper, we focus on the optimality of vertical location of the TS. As an optimality criterion, the sum of TS coordinates and orientation variances is used. To investigate the optimization problem, an analytical as well as a trial and error method is developed. Both methods showed that the height component has no significant influence on the optimal vertical placement of the TS. Inspection of results from the trial and error method, where the CPs are moved in different height layers, indicates differences in the height uncertainty of the establishment in micrometer range, which is negligible for most engineering applications.

  • 304.
    Alizadeh Khameneh, Mohammad Amin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. WSP Civils, Department of Geographic Information and Asset Management.
    Jensen, Anna B. O.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Horemuž, Milan
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Andersson, Johan Vium
    WSP Civils, Department of Geographic Information and Asset Management.
    Investigation of the RUFRIS Method with GNSS and Total Station for Leveling2017Conference paper (Refereed)
    Abstract [en]

    The establishment of leveling benchmarks for performing geodetic measurements, for instance in construction works, is usually costly and laborious due to a mass of field works in transferring the height from nearby known benchmarks. In this study, a real-time updated free station (RUFRIS) method is investigated to be used as an alternative approach for the traditional leveling. The coordinates of a RUFRIS station are determined by establishing a total station on the point, and performing a free-station by observing some points with both Real-Time Kinematic (RTK) GNSS and total station distance and direction observations. The study is conducted based on data from the East Link project in Sweden, where a 150 km long high-speed railway is to be constructed. The results show a standard deviation of 7 mm between the RUFRIS and leveling heights in this project and imply the feasibility of replacing the traditional leveling methods with RUFRIS in projects with low accessibility to benchmarks.

  • 305.
    Alizadeh Khameneh, Mohammad Amin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. WSP Civils, Department of Geographic Information and Asset Management.
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Jensen, Anna B. O.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Optimisation of GNSS Networks - Considering Baseline Correlations2017In: Survey review - Directorate of Overseas Surveys, ISSN 0039-6265, E-ISSN 1752-2706, p. 1-8Article in journal (Refereed)
    Abstract [en]

    By considering GNSS observations one can perform optimisation according to some pre-defined criteria and come up with the best location of receivers and optimum number of baselines. In practice, it is quite common to neglect the effect of correlations between baselines, and instead assume single-baseline adjusted data in the optimisation procedure. However, in each session of observation usually more than two receivers are simultaneously taking data from a number of common GNSS satellites, implying that the single or double difference observations are correlated. Our study designs an optimal observation plan for a GPS network in Skåne in southern Sweden, with the aim of determining possible displacements. Assuming three receivers in each session of observations leads to correlation between the GPS baselines, and consequently a fully populated weight matrix for each session of observation. A bi-objective optimisation model of precision and reliability is chosen to optimise the variance factor of each session, and eventually, design an observation plan. It is shown in this study that observing 6 out of 10 possible sessions are sufficient to enable the network to detect a 5 mm displacement at each station. Assuming that the double difference phase observations are uncorrelated changes the observation plan by retaining 2 more sessions. However, defining the weight matrix based on the double difference observations requires the correlations to be taken into account, and neglecting them leads to incorrect results.

  • 306.
    Alizadeh Khameneh, Mohammad Amin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning. WSP Civils, Department of Geographic Information and Asset Management.
    Sjöberg, Lars
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Jensen, Anna B. O.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Satellite Positioning.
    Optimization of GNSS Deformation Monitoring Networks by Considering Baseline Correlations2016In: FIG Working Week 2016 Proceedings, 2016Conference paper (Other academic)
    Abstract [en]

    In the study of deformations of man-made constructions or in geodynamics one usually needs to carefully monitor fixed objects attached to the deformable body. The purpose is to use precise observations to build up an accurate, reliable and possibly low-cost network around the objects to study their motion in short- or long-time intervals and to estimate the possible displacements or deformations among those objects. Frequently, such studies are performed to prevent unwanted disasters (e.g. due to earthquakes and landslides as well as the progressive or abrupt destruction of large-scale structures). This study is concerned with designing an optimal GNSS network to monitor possible deformations of a geodetic network.

    By considering GNSS observations one can perform the optimization according to some pre-defined criteria and come up with the best location of receivers and optimum number of baselines. In practice, it is quite common to neglect the effect of correlations between baselines, and instead use single-baseline adjusted data in the optimisation procedure. However, in each session of observation usually more than two receivers are simultaneously taking data from a number of common GNSS satellites. This procedure inevitably leads to between-baseline correlations. Our study designs an optimal observation plan for a GNSS monitoring network with the aim of determining possible displacements and deformations. The developed methodology will be tested on a simulated network with five points, where three receivers simultaneously take data from four satellites.

  • 307.
    Alizadeh-Khameneh, Amin
    et al.
    Department of Geographic Information and Asset Management, WSP, Stockholm, Sweden.
    Horemuz, Milan
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management, Surveying – Geodesy, Land Law and Real Estate Planning.
    Andersson, Johan Vium
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management, Surveying – Geodesy, Land Law and Real Estate Planning. Department of Geographic Information and Asset Management, WSP, Stockholm, Sweden.
    Wahlund, Sara
    Department of Geographical Information West, WSP, Gothenburg, Sweden.
    Jämtnäs, Lars
    Department of Geodetic Infrastructure, Lantmäteriet, Gävle, Sweden.
    A field method to estimate the uncertainty of RTK measurements2023In: Survey review - Directorate of Overseas Surveys, ISSN 0039-6265, E-ISSN 1752-2706, p. 1-8Article in journal (Refereed)
    Abstract [en]

    The expected accuracies obtainable with Network Real-Time Kinematic (NRTK) measurements are of interest to surveyors working on construction projects. This study introduces an NRTK-based free stationing method called RUFRIS (Real Time Updated Free Station) which is independent from physically marked points. Integration of total station distance and direction observations with NRTK measurements enables uncertainty estimation of both total station and surveyed NRTK points. In Sweden, NRTK is conducted using the national network of permanent reference stations with different densifications (10, 35, 70 km). This paper investigates the applicability of the RUFRIS-method to estimate the uncertainty of NRTK measurements in the field.

  • 308.
    Al-Karawi, Hassan
    et al.
    Chalmers University of Technology.
    Leander, John
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Al-Emrani, Mohammad
    Architecture and Civil Engineering Department, Chalmers University of Technology, 412 96 Gothenburg, Sweden.
    Verification of the Maximum Stresses in Enhanced Welded Details via High-Frequency Mechanical Impact in Road Bridges2023In: Buildings, E-ISSN 2075-5309, Vol. 13, no 2, p. 364-Article in journal (Refereed)
    Abstract [en]

    High-frequency mechanical impact (HFMI) is an efficient post-weld treatment technique  that enhances fatigue strength in metallic welded structures. Steel or steel-concrete  composite road bridges, where the fatigue limit state often governs the design, compose one category of structures that can benefit from the application of this technology. To assert an improvement in fatigue strength using HFMI, the induced compressive residual stresses must be stable. Therefore, the maximum service stresses that can be allowed on HFMI-treated joints should be controlled to avoid the relaxation of the induced beneficial compressive stresses by HFMI treatment. Using statistical analysis of recorded traffic, this paper compares the measured maximum traffic loads to those generated by a load model. More than 870,000 and 470,000 recorded vehicles from traffic measurements in Sweden and the Netherlands are used in this analysis. To capture the characteristic bending moment, the daily maxima of the resulting measured load effect are combined with the extreme value distribution of the bending moment. In addition, it is found that the characteristic load combination is the best-studied option to assess the maximum stress in HFMI-treated weldments in road bridges.

  • 309.
    Al-Khaffaf, Lubna
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Khalil, Hala
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Effekt av fasändringsmaterial på hydratiseringprocessen hos Portlandcement: En experimentell studie2020Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The Phase change materials (PCM) have the ability to absorb and release heat as the temperature changes from high to low temperature and vice versa. The use of phase change materials has increased in the construction sector due to the established environmental requirements and the various application benefits, especially in the thermal comfort of building applications and construction of sustainable infrastructure around the world (Berardi and Gallardo, 2019). Over the past decade, many studies have been conducted on the thermal properties of PCM (phase change material), however, few studies have focused on the study effect of PCM on mechanical and physical properties, although of great importance. In this work, three different microencapsulated types of phase change material (PCM) have been studied, while its effect on the mechanical and hydration properties of the cement paste with regard to constant ratio of water to cement ratio has been taken into account. The PCMs that have been studied are the following: Microencapsulated PCM, which is Nextek 24 D, Nextek 57D (Microtek Laboratories) and Croda Therm ME29P (Croda). In this study, various tests were performed on cementitious paste mixed with different doses of PCM to test the effect that PCM has on the cement hydration (under semi-adiabatic and isothermal conditions), the physical properties (setting time, slump flow, density) and the mechanical properties ( compressive strength). The results of this study indicated that both the melting point of the PCM and its amount have a decisive effect on the properties of the cement paste. Finally, the following conclusions have been drawn: • Additions of different dosage levels of the 24D and Croda PCM types showed that an increase in the dosage resulted in impaired mechanical and physical properties such as compressive strength of the cement paste (mechanical) decreased, and the density and random flow decreased (physical). While Nextek 57D did not show a great effect on cement paste according to density and random flow, which gives reduced negative impact on cement paste workability (physical). According to the mechanical properties, Nextek57D PCM with different levels of levels showed immediate positive effect on cement paste compressive strength compared to reference paste (no addition of PCM), and other cement pastes with other PCM types used in this study. • Mikrotek 57D PCM also gives a positive effect at different dose levels compared to two other types of Nextek 24D and Croda PCM regarding the effect of heat flow, which gives rise to hydration heat during the cement hydration process. However, other types of Nextek 24D and Croda in all quantities showed negligible effect on the heat flow during the cement hydration process.

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  • 310.
    Allahvirdizadeh, Reza
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Improving the Dynamic Design Philosophy of High-Speed Railway Bridges Using Reliability-Based Methods2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Modern railway infrastructures, especially bridges, are exposed to significant vibrations with potential safety implications. In this context, previous studies have shown the inconsistency and inadequacy of some conventional design methods necessitaing them to be improved. The assessment of safety inherently deals with uncertainties. Therefore, the current study is dedicated to this objective using reliability-based methods. Of the various possible failure modes, the investigations presented here are limited to running safety and passenger comfort. The investigation of these limit-states requires constructing complex computational models with train-track-bridge interaction capabilities. However, the application of these computationally intensive models in the context of structural reliability does not appear to be feasible. Simplifying the system, the vertical acceleration and the deflection of the bridge serve as implicit limit-state measures. Initially, using First Order Reliability Method (FORM) revealed limitations in the application of the current safety factor, resulting in inconsistent reliability indices. Therefore, probabilistic design curves are proposed, defining minimum required bridge mass and stiffness based on cross-section types, span configurations and train speeds. These results are obtained by formulating a FORM-based optimization. Subsequently, the results are used to investigate the sensitivity of the estimated failure probabilities with respect to the contributing basic random variables. Acknowledging the limitations of FORM, surrogate-assisted simulation-based reliability assessments were used for further investigations. A comparison of the performance of widely used regression-based surrogate models under an identical active learning scheme showed the superior performance of the Kriging method over the others. Within areliability-based design optimization framework, this Kriging model facilitates the generation of new probabilistic design curves. This is achieved by reformulating the conventional method to account for the dependency between design variables using the copula concept. In addition, the surrogate model aided in calibrating the safety factor associated with the vertical acceleration threshold, leading to a proposal of 1.38 as a new safety factor. Subsequently, the influence of soil-structure interaction on the estimated reliability indices is evaluated using an ensemble of classification-based surrogate models. Results highlighted its beneficial contribution in terms of increased damping for shorter spans, countered by adverse effects due to frequency shortening in longer bridges. Finally, the epistemic uncertainties arising from the limited knowledge of the vertical acceleration threshold are investigated. It is found that neglecting these uncertainties can lead to an overestimation of allowable train speeds by about 13%.

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  • 311.
    Allahvirdizadeh, Reza
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Reliability-Based Assessment and Optimization of High-Speed Railway Bridges2021Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Increasing the operational speed of trains has attracted a lot of interest in the last decades and has brought new challenges, especially in terms of infrastructure design methodology, as it may induce excessive vibrations. Such demands can damage bridges, which in turn increases maintenance costs, endangers the safety of passing trains and disrupts passenger comfort. Conventional design provisions should therefore be evaluated in the light of modern concerns; nevertheless, several previous studies have highlighted some of their shortcomings. It should be emphasized that most of these studies have neglected the uncertainties involved, which preventsthe reported results from representing a complete picture of the problem. In this respect, the present thesis is dedicated to evaluating the performance of conventional design methods, especially those related to running safety and passenger comfort, using probabilistic approaches. To achieve this objective, a preliminary study was carried out using the first-order reliability method for short/medium span bridges passed by trains at a wide range of operating speeds. Comparison of these results with the corresponding deterministic responses showed that applying a constant safety factor to the running safety threshold does not guarantee that the safety index will be identical for all bridges. It also shows that the conventional design approaches result in failure probabilities that are higher than the target values. This conclusion highlights the need to update the design methodology for running safety. However, it would be essential to determine whether running safety is the predominant design criterion before conducting further analysis. Therefore, a stochastic comparison between this criterion and passenger comfort was performed. Due to the significant computational cost of such investigations, subset simulation and crude Monte-Carlo (MC) simulation using meta-models based on polynomial chaos expansion were employed. Both methods were found to perform well, with running safety almost always dominating the passenger comfort limit state. Subsequently, classification-based meta-models, e.g. support vector machines, k-nearest neighbours and decision trees, were combined using ensemble techniques to investigate the influence of soil-structure interaction on the evaluated reliability of running safety. The obtained results showed a significant influence, highlighting the need for detailed investigations in further studies. Finally, a reliability-based design optimization was conducted to update the conventional design method of running safety by proposing minimum requirements for the mass per length and moment of inertia of bridges. It is worth mentioning that the inner loop of the method was solved by a crude MC simulation using adaptively trained Kriging meta-models.

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  • 312.
    Allahvirdizadeh, Reza
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    A framework recommendation for updating running safety design criteria of non-ballasted railway bridges using statistical investigations2023Conference paper (Refereed)
    Abstract [en]

    As far as the authors are aware, the threshold for vertical acceleration of the bridge deck was chosen based on the assumption that the induced dynamic loads would overcome gravity at higher accelerations, resulting in loss of contact between wheels and rail; however, the previous studies do not support this hypothesis. Considering these inconsistencies, a better understanding of the simplified design criteria is essential before conducting further studies suchas the calibration of partial safety factors. Therefore, this study considers a set of representative design scenarios to statistically compare wheel-rail contact loss with other criteria that can bederived from moving load models, such as vertical accelerations and bridge deck deflections. Based on the analyzes performed, deflection seems to be a better criterion than acceleration to control the running safety limit-state; although the results presented do not necessarily show avery strong correlation between these two criteria. Therefore, the k-means clustering approach isused together with 5% lower quantiles of the collected data to propose potential new thresholds. It should be noted that due to the limited number of analyzes, the approach presented in this study can be considered as a possible framework for further updates of the current design method rather than drawing general conclusions.

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  • 313.
    Allahvirdizadeh, Reza
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Applicability of meta-model assisted reliability assessment for dynamic problems: a comparison between regression-based methods2023In: Proceedings 14th International Conference on Applications of Statistics and Probability in Civil Engineering, ICASP14, Trinity College Dublin , 2023Conference paper (Refereed)
    Abstract [en]

    There is a growing intent among engineers, stakeholders, and decision makers to use probabilistic methods for infrastructure assessment or design objectives. However, the corresponding limit state for such problems usually requires the construction of complex computational models, usually using commercial software without parallelization capability. Such a requirement makes performing reliability analysis computationally prohibitive, which is even more challenging for dynamic problems, since a very short time step is required to obtain sufficiently accurate predictions. This concern has led to several methods being proposed to surrogate the limit state function with a generally black box called a meta-model. A variety of them, such as Kriging, Polynomial Chaos Expansion (PCE), Artificial Neural Networks (ANN), and response surfaces (e.g., polynomial, spline, or radial-base functions), have been adopted for this purpose. These meta-models are typically trained on a limited data set collected by computing the true responses of carefully selected input variables. Their applicability for assessing the probability of failure has been studied individually in the literature for both benchmark and practical problems. However, as far as the authors are aware, no comparison has been made between them for dynamic problems. This comparison needs to be made from the point of view of both accuracy and performance (number of calls to the limit state function). In this context, this paper takes a systematic approach to evaluate their performance under identical conditions, i.e., with similar training datasets. For this purpose, the dynamic response of railway bridges with different spans excited by the passage of trains with a wide range of speeds is used as a reference problem.

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  • 314.
    Allahvirdizadeh, Reza
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Estimating Running Safety Factor of Ballastless Railway Bridges Using Tail Modelling2022In: Acta Polytechnica CTU Proceedings, Czech Technical University in Prague - Central Library , 2022, Vol. 36, p. 25-32Conference paper (Refereed)
    Abstract [en]

    Excessive vertical acceleration of ballastless railway bridges subjected to vibrations induced by passing trains is one of the governing design criteria for bridges in high-speed lines. However, to the authors' knowledge, the corresponding design limit is not based on a solid theoretical or experimental background. Moreover, the traditionally applied safety factor also suffers from these concerns. Therefore, in the present study, a crude probabilistic approach is adopted to evaluate the consistency and reliability of this safety factor. For this purpose, deterministically designed bridges (using conventional methods) with short to medium spans are considered. Then, their reliability is evaluated using simulation-based techniques and extreme value theory, i.e., tail approximation. Then, the existing safety factor is calculated to evaluate the consistency of the current approaches, and possible new values are proposed based on the desired target reliabilities.

  • 315.
    Allahvirdizadeh, Reza
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Partial safety factor calibration using surrogate models: An application for running safety of ballasted high-speed railway bridges2024In: Probabilistic Engineering Mechanics, ISSN 0266-8920, E-ISSN 1878-4275, Vol. 75, article id 103569Article in journal (Refereed)
    Abstract [en]

    Traditionally, regulations employ semi-probabilistic methods with partial safety factors to control design limits. Calibrating these partial safety factors involves estimating the target reliability level and optimizing the partial safety factor values in order to minimize the deviation of the safety index between the considered design scenarios and the target value. This procedure necessitates performing a demanding amount of reliability analyses and is often carried out for simplified design situations. Therefore, high computational costs must be accepted for design problems formulated with complex computational models. This study implements a meta-modeling approach based on active learning in the partial safety calibration procedure, enabling its application to computationally intensive problems. Subsequently, the approach is applied to the running safety of ballasted high-speed railway bridges. This limit state implicitly accounts for the phenomenon of ballast destabilization, the occurrence of which disturbs the load path from the rail level to the bridge structure. The dramatic increase in train operating speeds in recent decades has increased the possibility of this design limit state being violated due to resonance. Despite the evident safety concerns, the adopted safety factors appear to be solely based on engineering judgments rather than calibration through higher-level reliability analysis. Therefore, the proposed calibration method is employed to determine the corresponding partial safety factors for various maximum allowable operating train speeds. The newly calibrated partial safety factors allow for a permissible maximum vertical acceleration of the bridge deck approximately 25% higher than the conventional design approaches. Therefore, incorporating these factors into the design procedure may lead to the construction of lighter bridges.

  • 316.
    Allahvirdizadeh, Reza
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Probabilistic dynamic design curves optimized for high-speed reinforced concrete railway bridges using first order reliability methodManuscript (preprint) (Other academic)
    Abstract [en]

    Increasing the operating speed of trains in modern railway networks can induce greater actions on the infrastructure than was previously the case. This is due, in particular, to the occurrence of the resonance phenomenon in railway bridges, which is the focus of this article and was not traditionally considered as a concern. In this context, the vibrations experienced by bridges, both vertical accelerations and displacements, are limited by design regulations to ensure that the safety of train passages over bridges and the comfort of passengers are guaranteed. However, previous studies have shown that the conventional dynamic design methods do not always result in conservative designs, nor is the achieved safety always consistent. Therefore, a probabilistic approach is adopted in this study to optimize the cross-section properties of various railway bridges in a widedesign range including section types, span lengths, and number of spans. For this purpose, an iterative line search based optimization problem is formulated to minimize the depth of the cross-sections under consideration and consequently the linear mass of the bridges. Meanwhile, the associated failure probabilities of the above dynamic limit states are constrained to be less than the desired level of safety by incorporating them in to the optimization constraint. In this regard, First Order Reliability Method (FORM) is adopted to perform reliability analyses. Thus, the obtained results are presented in the form of design curves that may assist designers to select minimum cross-section dimensions satisfying the desired level of safety in terms of dynamic limit states. This objective can be achieved using the proposed design curves without the need to construct associated complex computational models and perform computationally expensive dynamic analyses.

  • 317.
    Allahvirdizadeh, Reza
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Reliability assessment of running safety criteria of railway bridges considering soil-structure interaction effects using ensemble of classification-based surrogate modelsManuscript (preprint) (Other academic)
    Abstract [en]

    The increasing speeds of modern trains lead to excessive vibrations on the bridges, which have the potential to destabilize the ballast particles of the track. The occurrence of this phenomenon not only increases the track maintenance cost, but can also disrupt the load path from the rail level to the bridge deck, posing a risk to the train running safety. The design regulations indirectly control this limit-state by limiting the vertical acceleration of the bridge deck to a threshold value. The assessments pertaining to this purpose often neglect the soil-structure interaction (SSI) effects considering that as a conservative assumption. Such effects can positively contribute by increasing the system damping, but they can also increase the bridge flexibility making it more susceptible to vibrations. Therefore, this study investigates the influence of considering/disregarding SSI effects on the running safety criterion using a probabilistic methodology. The results are classified based on the maximum permissible train speeds and the bridge span length. Due to the high computational costs of the reliability analyses, the limit-state is approximated by an ensemble of classification-based surrogate models using the stack-generalization concept. Subsequently, the upper/lower bounds of the failure probability in the presenceof SSI effects are compared with those obtained for simply-supported bridges. It is pointed out that neglecting SSI effects for shorter span bridges may lead to an underestimation of system safety. For longer span bridges, however, this may lead to an overestimation of safety, which means that a non-conservative system can be designed.

  • 318.
    Allahvirdizadeh, Reza
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Reliability assessment of the dynamic behavior of high-speed railway bridges using first order reliability method2020In: Proceedings of the International Conference on Structural Dynamic , EURODYN, European Association for Structural Dynamics , 2020, p. 3438-3450Conference paper (Refereed)
    Abstract [en]

    The operational speed of the trains is intended to be significantly increased forthcoming; which consequently questions the safety level of the current design concepts concerning different performance limits. Thus, the reliability of the simply supported single-span bridges is assessed in the current article adopting the first-order reliability method (FORM) approach. In this regard, the dynamic response of the aimed bridges is investigated under the passage of a series of moving loads using available closed-form solutions in the literature. Hereof, axle load, car body/train configuration, flexural rigidity, damping, mass and model uncertainties are considered as random variables; while train-track-bridge interactions are neglected and the procedure is repeated for a wide range of span lengths and train velocities. Then, the safety index corresponding to each case is evaluated by considering running safety as the limit state function; where, the bridge deck vertical acceleration is taken as the capacity of the system. The outcomes are presented as average probability of exceeding the limit state versus train speed and categorized based on span lengths.

  • 319.
    Allahvirdizadeh, Reza
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges. Swedish Transport Administration.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Reliability Assessment of the Dynamic Behavior of High-Speed Railway Bridges Using First Order Reliability Method2020In: Proceedings of the 11th International Conference on Structural Dynamics, / [ed] M. Papadrakakis, M. Fragiadakis, C. Papadimitriou, Athens, Greece, 2020, Vol. 2, p. 3438-3450, article id 18654Conference paper (Refereed)
    Abstract [en]

    The operational speed of the trains is intended to be significantly increasedforthcoming; which consequently questions the safety level of the current design conceptsconcerning different performance limits. Thus, the reliability of the simply supportedsingle-span bridges is assessed in the current article adopting the first-order reliabilitymethod (FORM) approach. In this regard, the dynamic response of the aimed bridges isinvestigated under the passage of a series of moving loads using available closed-form solutions in the literature. Hereof, axle load, car body/train configuration, flexural rigidity,damping, mass and model uncertainties are considered as random variables; while traintrack-bridge interactions are neglected and the procedure is repeated for a wide range ofspan lengths and train velocities. Then, the safety index corresponding to each case isevaluated by considering running safety as the limit state function; where, the bridge deckvertical acceleration is taken as the capacity of the system. The outcomes are presentedas average probability of exceeding the limit state versus train speed and categorized basedon span lengths.

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  • 320.
    Allahvirdizadeh, Reza
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Surrogate-assisted investigation on influence of epistemic uncertainties on running safety of high-speed trains on bridges2024In: Probabilistic Engineering Mechanics, ISSN 0266-8920, E-ISSN 1878-4275, Vol. 75, article id 103559Article in journal (Refereed)
    Abstract [en]

    The operational safety of high-speed trains traversing ballasted bridges is contingent upon the prevention of the ballast destabilization, which can interrupt load transfer from the rail to the bridge. Current design regulations indirectly address this limit-state by specifying a threshold value for the vertical acceleration of the superstructure. This value represents the condition at which the inertial forces induced by train passage exceed the resistive forces. However, this approach is based on limited experimental data and the influence of numerous parameters remains unexplored. As a result, reliability analyses pertaining to running safety are hampered by a lack of knowledge, leading to greater epistemic uncertainties. In this study, the impact of such uncertainties on this dynamic system is investigated using surrogate-based Imprecise Structural Reliability Analysis (ISRA). For this purpose, parametric probability boxes are used to represent lower and upper bounds of the cumulative distribution function for basic random variables with epistemic uncertainties and surrogate models are adaptively trained to reduce computational costs. The obtained results show that neglecting the influence of epistemic uncertainties can lead to permissible operating train speed higher than the speed corresponding to the desired reliability level. In this study, an overestimation of about 13% was observed on average. Furthermore, the rough analyses carried out show that taking epistemic uncertainties into account can lead to a reduction of the system characteristic safety factor by up to 30%. This significant reduction underlines the importance of expanding the available knowledge on the phenomenon of ballast instability.

  • 321.
    Allahvirdizadeh, Reza
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Davoodi, Reza
    Faculty of Management, University of Tehran, Tehran, Iran.
    Golshan, Zaynab
    Department of Energy Engineering, Smteam GmbH, Zurich, Switzerland.
    Traditional energy saving techniques and geothermal heating and cooling systems2020In: Design of Energy-Efficient Buildings, Nova Science Publishers, Inc. , 2020, p. 95-130Chapter in book (Other academic)
    Abstract [en]

    After the industrial revolution, the modern human revised his point of view regarding development and generally his expectations from life. The new idea led him to defeat nature instead of traditional life philosophy stressing harmony and compatibility. It may seem exaggerated but the modern human ignored Mother Nature by violating history lasting peace and starting a battle. Thus, he invented modern instruments (machines) empowered by new energy sources. The greatest portion of this energy demand was supplied by fossil fuel consumption; which in spite of its undeniable role in intended development, numerous drawbacks are distinguished. For instance, it is estimated that the average temperature of the earth is approximately 0.8°C increased since the 1970s. The current chapter does not concern rejecting achieved progress; nevertheless, it aims to highlight the potential of learning from traditional architecture and adopting their experiences to fulfill modern expectations. In this regard, Iranian classical architecture, particularly at hot arid climate, is taken into account. Thus, relevant literature is surveyed to extract developed strategies leading to energy saving in residential buildings. Wider use of renewable energy and elevated energy efficiency are key factors to limiting GHG emissions. Geothermal energy is one of the most significant alternate sources of thermal and electrical energy. The geothermal energy adopted mostly through GCHP systems that are often introduced as ground-source heat pumps (GSHPs). Geothermal heating and cooling systems are heat pumps that extract and convey heat from the ground through a series of liquid-filled, underground pipes connected to a building. It is observed that geothermal heating is more efficient than electric, gas and oil-fried heating. They also are more efficient than air heat pumps as the extract heat from and inject heat into the ground since the ground temperature is almost consistent in different seasons comparing to the air temperature.

  • 322.
    Allahvirdizadeh, Reza
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Ensemble Meta-Models for Running Safety Assessment ofHigh-Speed Railway Bridges Considering Soil-StructureInteraction Effects2022Conference paper (Refereed)
    Abstract [en]

    Increasing operating speeds and axle loads of trains may induce higher verticaldeck accelerations on bridges, which may subsequently lead to the occurrence of ballast instabilities.This phenomenon not only increases maintenance costs but also leads to speed restrictionsunder operating conditions. In severe cases, it can also cause train derailment. Thishas been shown to be the governing criterion for the design of short to medium span lengthhigh-speed railway bridges, especially from the dynamic behaviour point of view. Despiteits substantial importance in the design of railway bridges, the conventional deterministic approachescannot achieve the desired level of safety (Allahvirdizadeh et al. 2020). Therefore,this article is devoted to the evaluation of the probability of violating running safety usingsimulation-based methods. In this context, different variables, including those for the bridge(span length, flexural rigidity, and geometric properties), for the train (axle load, dominantfrequency and damping ratio) and for the boundary conditions (soil and foundation properties)are considered. Due to the high computational cost and complexity of the consideredperformance function, a low-cost meta-model is trained using stack modelling concept as acombination of support vector machines (SVM), k-nearest neighbours (k-NN) and decisiontrees. Then, the range of maximum and minimum probabilities of exceeding the verticalacceleration threshold are evaluated as a function of train speed and bridge span length. Comparingthese boundaries with corresponding results of simply-supported bridges showed thatneglecting soil-structure interaction effects in shorter span bridges may result an underestimatedsafety of the system; however, for longer span bridges it may result in overestimatedsafeties.

  • 323.
    Allahvirdizadeh, Reza
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Minimum Design Requirements of High-Speed RailwayBridges Using Reliability-Based Design OptimizationManuscript (preprint) (Other academic)
    Abstract [en]

    Constructing high-speed railway networks received a great attention during pastdecade raising new safety concerns on infrastructure (particularly bridges). It ismainly because of possible excessive vibrations due to higher operating speeds.In this regard, deficiency or vague scientific background for some of designmethodologies are shown by former studies; among which is the adopted safetyfactor for running safety. This limit state occurs if the load path from the trainto the bridge is disturbed by dislocating ballast particles because of excessivevertical accelerations of the bridge deck. Hence, the current article is devotedto update the conventional design methodology. For this objective, reliabilitybaseddesign optimization technique is employed to propose minimum allowablemass and stiffness (or maximum permissible fundamental frequency) which assuressatisfying target reliability level. This is achieved by adaptively trainingKriging meta-models to surrogate the computational models. It seems that theproposed method can result in lighter (economical) bridges in comparison tothe conventional design methodology; however, this beneficial aspect vanishesby increasing span length of the bridge.

  • 324.
    Allahvirdizadeh, Reza
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Surrogate-assisted versus subset simulation-based stochastic comparison between running safety and passenger comfort design criteria of high-speed railway bridges2021In: Proceedings of the31st European Safety and Reliability Conference(ESREL 2021) / [ed] Bruno Castanier, Marko Cepin, David Bigaud, and Christophe Berenguer, 2021, p. 3334-3341Conference paper (Refereed)
    Abstract [en]

    Limiting the maximum vertical acceleration and deflection of the deck are two principal design criteriaof high-speed railway bridges. The former prevents ballast instability to ensure running safety, andthe latter attempts to limit the acceleration of the car-body below the level at which passengercomfort is disturbed. The previous studies are mainly concerned with the destabilization of the ballast,nevertheless the possibility of the maximum deflection occurrence should not be underestimated.Moreover, the literature indicates the need to improve the current design requirements including theminimum allowable mass and frequency of bridges, which requires solving optimization problems basedon modern requirements. Therefore, a probabilistic framework with simulation-based techniques is usedto evaluate the violation probability of the above limit states and distinguish dominant criteria underdifferent conditions, i.e., bridge span length and operational train speed. First, the performance of thesubset simulation method is compared with the Latin Hypercube-sampling based Monte-Carlo approachsupported by surrogate models. Polynomial chaos expansion (PCE) surrogate models are trained for thisobjective. Then, the resulting violation probabilities are evaluated for the two considered limit statesusing the approach with better performance.

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  • 325.
    Allawirdi, Teresa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Gunduz, Helen Rebecka
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Tidsplanering och visualisering inom anläggningsprojekt2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
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  • 326. Allen, J.
    et al.
    Cars, Göran
    KTH, School of Architecture and the Built Environment (ABE).
    Madantpour, A.
    Introduction2012In: Social Exclusion in European Cities: Processes, Experiences and Responses, Taylor and Francis Inc. , 2012, p. 7-20Chapter in book (Refereed)
  • 327.
    Allenbrant, Axel
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management, Real Estate Business and Financial Systems.
    Nasser, Leif
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management, Real Estate Business and Financial Systems.
    Balansgången mellan energikrav och kulturarv: En kvalitativ studie om hur energiåtgärder påverkar förvaltning och värdering av kulturhistoriska fastigheter2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study focuses on the trade-off between energy efficiency requirements and thepreservation of cultural heritage in the context of cultural historical buildings. The aim is toexplore how the management and valuation of these buildings may be affected by futureenergy requirements, with a particular focus on the potential consequences this may have forproperty owners, managers and other stakeholders. The study uses a combination of literaturestudy and a qualitative study based on semi-structured interviews with property owners andproperty appraisers. The central findings show that it is challenging to make heritagebuildings energy efficient to the required levels, and that the valuation of such buildingsrequires a special skill in balancing subjective preferences with objective criteria, given thedifferent preferences of the market.

    Energy efficiency of heritage buildings can increase their commercial value by loweringoperating costs and making properties more attractive to environmentally consciousinvestors. However, such measures can be difficult to implement without compromising thecultural value of the building. The valuation of heritage properties therefore requires bothtechnical and cultural expertise. The study identifies a knowledge gap in the market regardingthis relatively new problem. It concludes by emphasizing the importance of navigatingthrough these complex issues to preserve our cultural heritage while addressing today'schallenges, such as the need for energy efficiency and sustainability.

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  • 328.
    Allenbrant, Axel
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Nasser, Leif
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Sociala obligationer inom fastighetssektorn: En studie om hur fastighetsbolag kan arbeta med sociala obligationer2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Since 2008, when SEB together with The World Bank launched the concept of green bonds,the market volume of these bonds have increased significantly on a yearly basis. During thelast decade Sweden has been the leading country in handing out these green bonds. This ismostly because of Sweden’s real estate companies, such as Vasakronan who were the first toissue a green corporate bond in 2013. But despite that we are still far behind in thedevelopment of the social bonds, even though these were first launched in Great Britain in2010, only 2 years after the introduction of the first green bond. It is considered to be tooundeveloped and fresh for the swedish real estate companies. We are moving towards a worldwhere more and more people decide to move their lives to the big city, and to reachsustainable development the focus should be on all three sustainability dimensions.

    This master’s thesis aims to answer the questions that real estate companies and investorshave regarding social impact bonds, and to increase the markets transparency. This has beenachieved through a literary and qualitative study, where the qualitative study has consisted ofinterviews. Seven interviews with relevant people have been conducted to examine thepossibilities and challenges with social impact bonds. The results show that there are certainchallenges, but primarily potential with the financing tool. The interviewees agree that themarket needs more clarity and that social washing and, in some cases, lack of transparency inthe market are the greatest challenges. To increase market clarity there should exist a moreclear set of rules which can be achieved through setting clear objectives. The study also showsthat there is an untapped market with a huge potential that future investors and real estatecompanies should take advantage of.

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  • 329.
    Allertz, Erik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Hjelmar, Tobias
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Kvalitetssäkring av material och tjänster inom byggentreprenadbranschen2011Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Quality is the key to a well executed product or service. The construction industry hasn’t highlighted the quality in recent times which have contributed to the construction industry receiving much criticism in the field. The public sees it as an offhanded industry where errors and delays are common.The reason for this is considered to be primarily the lack of time, constant pressure to reduce costs and skills and the ability to communicate between the parties about what the correct quality really means. The industry has begun to realize that it must start setting clearer standards and that there are great opportunities for improvement.This report will give Peab an opportunity to develop their quality work. The report highlights Peab residential area of Stockholm market position with the current quality of subcontractors and suppliers. It also provides suggestions on how Peab in a better way can work with quality and with this becoming a more competitive player in the market. The conclusions that can be drawn from this study is that Peab is aware of the problem and has begun work on improvements to enhance quality of work. Peab, for example, developed tools for gathering experience. Unfortunately these methods were used poorly and not to the degree that is required. Peab also works with partnering, based on long term business relationships. Correct use of partnering increases the chances of higher quality in the projects. Concrete proposals for improvements that this report highlights include higher standards in the procurement process, dare make demands on the quality of subcontractors and suppliers, learn from the mistakes made and disseminate the knowledge within the Group and work with long-term business relationships in which partners can develop one another .

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  • 330.
    Allmér, Gustaf
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Organization and management.
    Joakim, Svantesson
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Organization and management.
    How internal factors influence the work towards increased energy performance: A case study in a Swedish construction company2014Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    För  att  minska Europas klimatpåverkan ställer Sveriges regering och Europeiska Unionen allt högre krav på byggindustrin gällande energiprestandan i nybyggda flerbostadshus, då bostadssektorn idag står för en betydande del av Sveriges totala energiförbrukning. Byggföretagen jobbar numera för förbättrad energiprestanda i nybyggda bostäder, men skillnaden från projekt till projekt kan vara mycket stor. Man har i tidigare forskning studerat de externa faktorer som påverkar hur långt man är villig att gå energimässigt i bostadsprojekt, men lite forskning har bedrivits kring de interna faktorerna.

    Detta examensarbete har därför till syfte att identifiera dessa interna faktorer och även förklara varför de påverkar processen. För att studera detta har en fallstudie utförts på ett svenskt byggföretag där aktörer inom stora delar av den interna byggprocessen finns representerade. Semi strukturerade intervjuer genomfördes för att ge en så utförlig bild som  möjligt av processen och de faktorer som påverkar den. Intervjudatan sorterades, reducerades och analyserades genom stöd av ett teoretiskt ramverk. I detta ingår teorier från tidigare studier och olika Knowledge Managementteorier, vilka används för att tolka och förstå de faktorer som iakttagits. 

    Studiens resultat innefattar en redogörelse för viktiga observerade interna faktorer som påverkar processen i fallstudieföretaget mot mer energieffektiva flerbostadshus. Exempel på dessa är: individers kunskap och åsikt om ökad energiprestanda, tidpunkten i projektet då energifrågan lyfts upp, hur kunskap återvinns inom företaget, hur man följer upp energiberäkningar och val av medium för att dela kunskap. Många av de faktorer som identifierats är kopplade till vilken attityd och strategi  ledningen  väljer för energifrågan.  Den attityd som uppifrån förmedlas kommer också att antas av aktörerna i processen, och man har här möjligheten  att göra ett val i hur mycket man som företag vill satsa på fortsatt förbättrad energiprestanda.

  • 331. Allström, A.
    et al.
    Kristoffersson, Ida
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS. cVTI Swedish National Road and Transport Research Institute, Sweden.
    Susilo, Yusak
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, System Analysis and Economics.
    Smartphone based travel diary collection: Experiences from a field trial in Stockholm2017In: Emerging technologies and models for transport and mobility 44th European Transport Conference Selected Proceedings, Casa Convalescència, Barcelona, Spain, 5-7 October 2016, Elsevier, 2017, Vol. 26, p. 32-38Conference paper (Refereed)
    Abstract [en]

    Currently, there is a great need for new methods to collect travel data. Traditional methods have considerable drawbacks and, at the same time, the models used to analyse the transport system require more and more detailed and high-quality data. An alternative method that stands out as very promising is to capture raw data from devices that can use any positioning technology (e.g., GPS, WiFi positioning, GSM, etc.), followed by transforming the raw data into meaningful travel data. Since most smartphones are equipped with various sensors that can be used to determine the location of the smartphone, and since smartphones are integrated in the daily life of most people, they provide an unprecedented opportunity for large-scale travel data collection. This method has a great potential to solve the problems related to the estimation of distance/travel time, geographic coding of departure/destination locations and forgotten trips and it will also provide a more detailed and extensive data set. In a recently completed research project the feasibility of replacing or complementing the traditional travel diary, with a suite of tools that make use of smartphone collected travel data has been evaluated. The advantages and disadvantages of the traditional method and the proposed method were studied. For a fair comparison, both methods have been tested in the same city, at the same time, and with the same respondents. To achieve the objectives of the project, MEILI, a system that consists of a smartphone application for capturing the movement of users and a web application for allowing the users to annotate their movement, has been deployed. The recruitment of respondents is a critical phase for traditional travel diaries and, as expected, this was the case also for the smartphone based method. A lesson learnt was that it is important to simplify the registration process as much as possible. In total 2142 trips were collected and annotated by 171 users. 51 of the users annotated trips covering more than a week. The experiences from the field trial shows that a smartphone based travel diary collection is a very useful complement to traditional travel diary collection methods since it appeals to a different age group and collects more detailed travel data for a longer period. The main findings of the paper are that smartphone based data collection is feasible, that the algorithms to save battery work well and that trips of the same respondent vary considerably depending on day of the week.

  • 332. Allström, Andreas
    et al.
    Rahmani, Mahmood
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Gundlegård, David
    Archer, Jeffery
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Mobile Millennium Stockholm2011In: Proceedings of the 2nd International Conference on Models and Technologies for ITS, 2011Conference paper (Refereed)
  • 333.
    Allvin, Fanny
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Sedig, Johanna
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Underhåll av småhus utlagt på totalentreprenad: Finns det en efterfrågan?2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Vi har undersökt om det finns en marknad för ett underhållsavtal för småhusägare. Vår idé är att villaägare ska kunna teckna ett avtal med ett företag som i sin tur förhandlar med ett eller flera underhållsföretag. Huset besiktigas sedan och det görs upp en underhållsplan, med de åtgärder som villaägaren önskar ska ingå. Villaägaren kommer sedan att betala in en viss summa pengar enligt avtal varje månad till företaget, som ser till att underhållet sköts. Månadskostnaden är beroende av både vilka underhållsåtgärder som ingår och husets standard vid tecknandet av avtalet.

    För att undersöka om det finns en marknad har vi intervjuat fem villaägare och två underhållsföretag. Vi har även talat med Folke Björk, professor i byggvetenskap, angående hans syn på vår idé. Alla tre parter var generellt positiva till idén. Den främsta målgruppen för ett underhållsavtal bedömer vi är barnfamiljer och välbärgade pensionärer. Både företagen och privatpersonerna ansåg att det utvändiga underhållet skulle passa bäst för ett underhållsavtal, då det invändiga underhållet inte bara utförs för att det måste utan även för att man vill ha lite omväxling och fräscha upp huset. Det invändiga underhållet går dessutom i stor utsträckning att göra själv.

    Det vi har kommit fram till är att det finns en marknad för ett underhållsavtal men att det finns många aspekter att se över innan ett underhållsavtal skulle kunna tecknas i praktiken.

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  • 334.
    Almer, Anna-Klara
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Integrating remotely sensed hydrologic parameters into an index of sediment connectivity2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The expected increase in precipitation and temperature in Scandinavia, and especially short-time heavy precipitation, will increase the frequency of flooding. Urban areas are the most vulnerable, and specifically, the road infrastructure. The accumulation of large volumes of water and sediments on road-stream intersections gets severe consequences for the road drainage structures. The need for a tool to identify characteristics that impacts the occurrence of flooding, and to predict future event is thus essential.

    This study integrates the spatial and temporal soil moisture properties into the research about flood prediction methods. Soil moisture data is derived from remote sensing techniques, with focus on the soil moisture specific satellites ASCAT and SMOS. Furthermore, several physical catchments descriptors (PCDs) are used to identify catchment characteristics that are prone to flooding and an inventory of current road drainage facilities are conducted. Finally, the index of sediment connectivity (IC) by Cavalli, Trevisani, Comiti, and Marchi (2013) is implemented to assess the flow of water and sediment within the catchment. A case study of two areas in Sweden, Västra Götaland and Värmland, that was affected by severe flooding in August 2014 are included.

    The results show that the method with using soil moisture satellite data is promising for the inclusion of soil moisture data into estimations of flooding and the index of sediment connectivity.

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  • 335.
    Almlöf, Erik
    KTH, School of Industrial Engineering and Management (ITM), Engineering Design.
    Beyond Technology: Understanding societal impacts of implementing self-driving vehicle systems on road transport2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    During the last decade, self-driving vehicles have become a major topic of interest, promising to transform transport by making travel safer and more efficient. However, as we move closer to making these vehicles a reality, it has become clear that introducing them into society might not be as straightforward as once thought, and there are growing doubts about the benefits they are supposed to offer.

    In this thesis, I investigate the societal impacts of self-driving vehicles by exploring four aspects: reasons for researching self-driving vehicles, how these vehicles could be implemented, the societal impacts of fully implementing self-driving vehicles, and their relationship to sustainability goals.

    I find that the motivation for researching this topic is often opaque, and the existence of the technology itself is used as a justification for more research. 

    Furthermore, most research into realising self-driving vehicles focuses on purely technical aspects such as designing better algorithms. However, I show that many challenges remain connected to the sociotechnical intertwinement of self-driving vehicles. For instance, I illustrate how they will interact with pedestrians and how services using self-driving vehicles would be practically organised.

    Additionally, self-driving vehicles are likely to impact many aspects of society, such as congestion, accessibility, and economic factors. However, I demonstrate that no single framework successfully captures all the identified societal impacts, which are likely to depend on diverse factors such as geographical variations.

    The impacts further affect sustainability, where new challenges are likely to emerge. I show that while current tools to govern the transport system are still relevant, a comprehensive approach is needed to ensure that policymakers make well-considered decisions. 

    In conclusion, I call for a more balanced view of self-driving vehicles. Introducing this new technology requires careful planning and governance to ensure that self-driving vehicle systems genuinely enhance our quality of life and help build a sustainable future. 

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  • 336.
    Almlöf, Erik
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Exploring societal impacts of self-driving public transport using four-step transport models2022Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    During the last decade, self-driving technology has become increasingly visible in the news, with the vision that people would enter vehicles that drive themselves, and that people could instead rest, read the newspaper, or have a meeting. However, these visions have mainly focused on the potential for car usage, even though public transport could benefit greatly from self-driving technology. For bus traffic, the bus driver accounts for half of the cost of driving, and savings on personnel costs could, for example, be reinvested in expanded public transport service or used to lower taxes.

    At the same time, more research has shown potential problems linked to self-driving technology, for example that more comfortable driving would lead to more traffic, which in turn would lead to increased emissions, higher noise levels in cities or further focus on car-centric infrastructure. For public transport, the driver's role in creating safety and acting as problem solvers has also been emphasized - who should I ask for directions if there is no knowledgeable driver on board?

    Various methods have previously been used to explore the social effects of self-driving technology and in this dissertation I have used so-called "four-stage models", more specifically the Swedish transport model Sampers. Four-stage models have been used for 50 years to evaluate effects on the transport system from e.g. infrastructure changes, but these models face new challenges, handling vehicles that drive by themselves. In my research, I have adjusted the model to simulate self-driving technology and investigated what effects this has on, for example, traffic volumes and emissions.

    In the three articles that are part of the dissertation, I have four main conclusions:

    • Self-driving technology can mean large savings in costs for public transport, primarily for bus traffic but also to some extent for rail traffic. In addition, a smoother driving behaviour would mean more comfortable travel, which would increase the attractiveness of public transport. In addition, public transport not limited by, for example, driver schedules or current commercial conditions, could develop new types of services, such as on-demand public transport.
    • Four-stage models have previously been used to model the transport system and have been shown to have good results, at least at an overall level. Within my research, I have made some adaptations of these models to mimic self-driving technology, but the models in their current form cannot consider, for example, vehicle sharing.
    • It is important to point out that bus and train drivers currently perform many tasks that are not directly related to the driving of the vehicle, such as answering questions, maintaining social order among passengers and taking care of faults that occur during the trip. Today, self-driving technology cannot fulfil these roles.
    • Self-driving technology for public transport would affect people's accessibility, driving style for vehicles, safety on board, how we plan traffic and the people who currently work as drivers. In fact, a multitude of societal effects have been identified, affecting all areas of transport. In addition, the effects are generally not similar across geographies, time units or for different actors, which further emphasizes that the total effect is not easy to summarize.
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  • 337.
    Almlöf, Erik
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Jenelius, Erik (Contributor)
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    PSSST – Policies for sustainable, shared and self-drivingtransportation2022Report (Other (popular science, discussion, etc.))
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  • 338.
    Almlöf, Erik
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Acosta Carrascal, Henry (Author of introduction, etc.)
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Results for the comparison between e-scooter trips and their public transport and walking equivalent in the city of Gothenburg2023Report (Other (popular science, discussion, etc.))
    Abstract [en]

    This project examined shared e-scooter trips provided by the operator Voi and used a trip planner to determine the potential alternatives if users had chosen to walk or utilise public transportation (PT) instead.

     

    The analysis reveals that Voi trips are typically brief, with 71% lasting less than 10 minutes, usually covering 1-2 kilometres, and mostly occurring within central Gothenburg. The trip planner indicated that walking would be the best alternative for roughly half of the trips, while public transportation would be the main alternative for the other half. 

     

    For the trips for which the trip planner suggested walking as the best alternative, 81% of them are less than 1 km long, meaning they could be alternatively covered by walking 15 minutes or less. Nonetheless, 89% of trips are faster with Voi, and 72% of them begin or end within 100 metres of a public transport stop, which strongly implies intermodal behaviour among e-scooter users and the use of e-scooters as a first/last mile solution; however, further research is necessary to support this statement.

     

    Regarding the trips for which the trip planner suggested PT with no transfers, half of the users would have had to walk 500 m or more to access and egress PT and 80% of them started or ended within 100 m of a public transport stop, which can suggest users choosing Voi to replace a leg of their trips; or even the complete trip, considering that roughly half of these trips would have been theoretically cheaper with Voi instead of PT. Nonetheless, once again, more research is needed to support these hypotheses.

     

    Generally, shared e-scooters hold the potential to complement public transportation services in densely populated urban areas, a notion supported by this study and prior academic and grey research. Even in the absence of parking regulations, users tend to initiate or conclude their trips near public transport stops, which can serve as a valuable guideline for developing parking policy.

     

    In conclusion, shared e-scooters represent an important aspect of urban transportation that should not be overlooked. It is crucial to engage both existing and potential e-scooter operators in transportation planning to foster collaboration with municipalities, PT agencies and local communities. This collaborative effort should aim to promote multimodality, integrated ticketing solutions, and user-centric approaches that encourage a shift away from less sustainable transportation modes.

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  • 339.
    Almlöf, Erik
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Zhao, Xiaoyun (Contributor)
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Sjöström, Thomas (Author of introduction, etc.)
    Sweco ITS.
    Hjälmdahl, Magnus (Author of introduction, etc.)
    Sweco ITS.
    Larsson, Alva (Author of introduction, etc.)
    Sweco ITS.
    Slutrapport - Självkörande fullängdsbuss på Tvärförbindelse Södertörn2021Report (Other (popular science, discussion, etc.))
    Abstract [sv]

    Föreliggande slutrapport är finansierad av Trafikverkets FoI portfölj, strategiska  initiativ,för projekt Självkörande eldriven stombuss på Tvärförbindelse Södertörn – En skalbarfallstudie (TRV 2019/118695). Partners i projektet är Trafikverket, Scania, Volvo, Keolis,KTH samt Sweco där även Trafikförvaltningen Region Stockholm, Nobina och projektTvärförbindelse Södertörn har bidragit till arbetet som pågått från maj 2020 till mars 2021.Ansvarig för projektet inom Trafikverket har varit Stora projekt.För att skapa en förståelse för konsekvenser av tekniska utveckling i relation tillnödvändiga fysiska och digitala åtgärder har tre scenarier tagits fram: Bus Driver Plus,Automation with Adaption och Automation Utopia. Dessa scenarier beskriver olika nivåerav automation och behov av kringliggande stödsystem. I det första scenario finns enförare ombord på bussen som tar över körningen vid farliga situationer. Det andrascenariot avser en självkörande buss utan förare där den fysiska infrastrukturen haranpassats genom ett införande av ett eget busskörfält. Det sista scenariot beskriver enframtid där bussen helt förlitar sig på digital teknik och en operatör kontrollerar körningenav flera fordon från ett avsides kontrolltorn.De tre scenarierna utvärderades genom en samlad effektbedömning, Trafikverkets metodför att utvärdera åtgärder. Resultaten visar att den största vinsten av automatisering kanhandla om resenärernas bekvämlighet och inte nödvändigtvis om att minimera kostnaderför förare. Antaganden om att resenärerna kan uppleva resan bekvämare är troligtvisöverskattade, men resultaten visar att även små förbättringar i bekvämlighet kan ge storasamhälleliga vinster.Scenariot där bussen har ett eget körfält innebär mycket stora kostnader och är troligtvisinte ekonomiskt försvarbart. Dessutom kommer enbart en busslinje att trafikeramotorleden som dessutom består av 3 tunnlar. Vidare är det inte säkert att den aktör somgör nödvändiga investeringar är den aktör som får ta del av de samhälleliga vinsterna. Iscenariot skulle Trafikverket stå för stora delar av investeringskostnaden, medan vinsten för personalbesparingar uppstår för Region Stockholm och kollektivtrafikresenärerna somåker längs sträckan.Projektet har även undersökt hur multimodala hubbar (nod som möjliggör smidigt bytemellan olika transportmedel) längs med förbindelsen kan stödja eldrivna och självkörandebussar. Det är viktigt att ny väginfrastruktur bidrar till en attraktiv kollektivtrafik därresenärer i första hand väljer buss istället för bil. För att eldrivna och självkörande bussarska införas behöver Region Stockholm ställa nya krav i upphandlingar för attåstadkomma en förändring i transportsystemet. Nya krav som skapar ekonomiskaincitament för operatörer som utför den operativa verksamheten över lång tid. Det är dockproblematiskt att ställa krav på eldrift eftersom det saknas tillgänglig infrastruktur iStockholm.Avseende självkörande fullängdsbussar är tekniken helt enkelt inte tillräckligt mogen idag.Dock tror många experter att självkörande bussar kommer att införas, både i stadsmiljöoch glesbygd, när tekniken och samhället är redo för det, gissningsvis kring år 2030.

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  • 340.
    Almlöf, Erik
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Hesselgren, Mia
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Product and Service Design.
    From technological fixes to societal solutions: A sociotechnical framework for understanding self-driving technology implementation2024Manuscript (preprint) (Other academic)
    Abstract [en]

    Self-driving vehicles have been hailed as a revolutionary force that will benefit society through increased accessibility and reduced accident rates. However, implementing such a new technological system will be complex, requiring immense societal adaptions and changes. In this paper, we analyse the challenges faced in implementing self-driving vehicles based on interviews with onboard operators and stakeholders responsible for the operations of self-driving buses in northwest Stockholm, Sweden. From these interviews, we suggest a framework for understanding which societal changes would be required to implement self-driving vehicles.

    We highlight the complexities of self-driving and the sociotechnical perspective needed to understand the challenges of implementing self-driving vehicles, underscoring human drivers' complex and tacit knowledge. Further, we identify a crucial technological gap in the vehicles' understanding of context, suggesting that comprehensive self-driving operation requires a form of general intelligence beyond the current, specialised, driving-only intelligence. The findings presented in this paper pave the way for further research and efforts needed to enable broader adoption of self-driving vehicles and offer insights for policymakers to guide future legislation in self-driving transport. 

    In conclusion, several adaptions are required to facilitate self-driving vehicles. However, policymakers are advised to uphold stringent transport requirements, regardless of human or machine drivers, and resist any pressures to unnecessarily relax regulations. Such a cautious approach will ensure the continued prioritisation of safety and efficacy without compromising the human norms and behaviours that are integral and necessary to transport systems. 

  • 341.
    Almlöf, Erik
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL. Region Stockholm.
    Nybacka, Mikael
    Pernestål Brenden, Anna
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Will public transport be relevant in a self-driving future? A demand model simulation of four scenarios for Stockholm, Sweden2020In: Transportation Research Procedia 49, Association for European Transport , 2020, Vol. 49, p. 60-69Conference paper (Refereed)
    Abstract [en]

    The public sector makes long-term investments in for example tram rail lines and highways based on forecasts of future travelling but generally do not consider the impacts of self-driving technology as a factor. Several papers have presented transport system wide simulations with self-driving cars, exploring changes in mode choice, energy demand or the potential for sharing. Demand traffic models have been used in several studies, looking at modal choice changes, but the general assumption is that the public transport service remains unchanged, despite a large potential for governments to enhance service or reduce costs. This paper examines the effects of self-driving technology on the transport system with Stockholm, Sweden as a case study, looking at four scenarios which were developed with input from 130 transport professionals from industry, academia and the public sector. Each of the scenarios include one "car" and one "public transport" mode, looking at changes in e.g. modal choice and person kilometers traveled. The national demand model Sampers is used for evaluation. The results indicate a decrease in walking and bicycling in all scenarios and a decrease in public transport travelling in scenarios with a taxi-like car service. Although this result would mean a shift from public transport to car travel, the majority of travel to and from central parts of Stockholm were still made by public transport.

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  • 342.
    Almlöf, Erik
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Nybacka, Mikael
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Pernestål Brenden, Anna
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS. KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Will leisure trips be more affected than work trips by autonomous technology? Modelling self-driving public transport and cars in Stockholm, SwedenManuscript (preprint) (Other academic)
    Abstract [en]

    Self-driving technology may lead to a paradigm shift for the transport industry with shared cars available to everyone. However, this vision has increasingly been challenged as too optimistic and unsubstantiated. In this study we explore societal impacts of using this technology for both cars and public transport and investigate differences depending on geography and trip purpose. Four scenarios were designed through workshops with 130 transport experts, modelled using a conventional four-step model for Stockholm, Sweden and evaluated in terms of changes to mode choice, number of trips and person kilometres. 

    We find larger increases for non-commuting trips, i.e. service and leisure trips, than for commuting trips, questioning the view of the ‘productive work trip’ as self-driving technology’s main impact on society. As these trips are primarily made outside of rush hours, this may lead to a changed transport system. Geographic differences are substantial and heavily dependent on the cost model for car alternatives, even indicating a reduction in car travel in rural areas if private ownership would be replaced by shared cars. Furthermore, walking and cycling levels decreased in all scenarios while enhancing public transport using self-driving technology has a limited impact on ridership. 

    These results show that the impacts of self-driving technology may have varied societal impacts even within a region and may lead to increased car travel, especially off-peak. These conclusions stress the need for policies that are sensitive to both geography and time. 

  • 343.
    Almlöf, Erik
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Nybacka, Mikael
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Pernestål Brenden, Anna
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Will leisure trips be more affected than work trips by autonomous technology?: Modelling self-driving public transport and cars in Stockholm, Sweden2022In: Transportation Research Part A: Policy and Practice, ISSN 0965-8564, E-ISSN 1879-2375, Vol. 165, p. 1-19Article in journal (Refereed)
    Abstract [en]

    Self-driving technology may lead to a paradigm shift for the transport industry with shared cars available to every-one. However, this vision has increasingly been challenged as too optimistic and unsubstantiated. In this study we explore societal impacts of using this technology for both cars and public transport and investigate differences depending on geography and trip purpose. Four scenarios were designed through workshops with 130 transport experts, modelled using a conventional four-step model for Stockholm, Sweden and evaluated in terms of changes to mode choice, number of trips and person kilometres.We find larger increases for non-commuting trips, i.e. service and leisure trips, than for commuting trips, questioning the view of the 'productive work trip' as self-driving technology's main impact on society. As these trips are primarily made outside of rush hours, this may lead to a changed transport system. Geographic differences are substantial and heavily dependent on the cost model for car alternatives, even indicating a reduction in car travel in rural areas if private ownership would be replaced by shared cars. Furthermore, walking and cycling levels decreased in all scenarios while enhancing public transport using self-driving technology had a limited impact on ridership.These results show that the impacts of self-driving technology may have varied societal impacts even within a region and may lead to increased car travel, especially off-peak. These conclusions stress the need for policies that are sensitive to both geography and time.

  • 344.
    Almlöf, Erik
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Rubensson, Isak
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment.
    Cebecauer, Matej
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Who is still travelling by public transport during COVID-19?: Socioeconomic factors explaining travel behaviour in Stockholm based on smart card data2021Conference paper (Refereed)
    Abstract [en]

    The COVID-19 pandemic has changed travel behaviour and reduced the use of public transport throughout the world, but the reduction has not been uniform. In this study we analyse the propensity to stop travelling by public transport during COVID-19 for the holders of 1.8 million smart cards in Stockholm, Sweden. We suggest two models for explaining the change in travel pattern, linking socioeconomic data with the probability to stop travelling. We find that education level, income and age are strong predictors, but that workplace type also substantially affect the propensity of public transport travel. Furthermore, we use clustering to divide the population into five separate social groups, serving as a more intuitive understanding of how the pandemic has affected different citizens’ propensity to use public transport. The results can guide policy makers on how to better tail e.g. bus supply to local demand, either through an increased understanding of differences based on the results or by further incorporating the results into a transport simulation models.

  • 345.
    Almlöf, Erik
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Zhao, Xiaoyun
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL. School of Technology and Business Studies, Dalarna University, Falun, Sweden.
    Pernestål Brenden, Anna
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Nybacka, Mikael
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics. KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Frameworks for assessing societal impacts of automated driving technology2022In: Transportation planning and technology (Print), ISSN 0308-1060, E-ISSN 1029-0354, Vol. 45, no 7, p. 545-572Article in journal (Refereed)
    Abstract [en]

    Numerous studies have studied the impacts of automated driving (AD) technology on e.g. accident rates or CO2 emissions using various frameworks. In this paper we present an overview of previous frameworks used for societal impacts and review their advantages and limitations. Additionally, we introduce the Total Impact Assessment (TIA) framework developed by the Swedish Transport Administration and use this framework to evaluate three scenarios for AD bus services in Stockholm. We conclude that the reviewed frameworks cover different aspects of AD technology, and that e.g. cybersecurity and biodiversity are areas largely neglected. Furthermore, most frameworks assume effects to be homogenous, when there may be large variation in e.g. perceived security. The TIA framework does not manage to include all societal aspects of AD technology, but has great benefits and manages to provide important insights of the societal impacts of AD technology, especially how effects may wary for different actors. 

  • 346.
    Almlöf, Erik
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Zhao, Xiaoyun
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Pernestål Brenden, Anna
    KTH, School of Industrial Engineering and Management (ITM), Centres, Integrated Transport Research Lab, ITRL.
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Nybacka, Mikael
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Frameworks for assessing societal impacts of self-driving technologyManuscript (preprint) (Other academic)
    Abstract [en]

    Numerous studies have studied the impacts of self-driving technology on e.g. accident rates or CO2 emissions using various frameworks. In this paper we present an overview of previous frameworks used for societal impacts, and review their advantages and limitations. Additionally, we introduce the Total Impact Assessment (TIA) framework developed by the Swedish Transport Administration and use this framework to evaluate three scenarios for self-driving bus services in Stockholm. We conclude that the reviewed frameworks cover different aspects of self-driving technology, and that e.g. cybersecurity and biodiversity are areas neglected by most frameworks. Furthermore, most frameworks assume effects to be homogenous, when there may be large variation in e.g. perceived security. The TIA framework does not manage to include all societal aspects of self-driving technology, but has great benefits and manages to provide important insights of the societal impacts of self-driving technology, especially how effects may wary for different actors.

  • 347.
    Al-Mousa, Mohammad
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Kordnejad, Behzad
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Capacity Allocation of Unmonitored Railway Yards2023In: TRA Lisbon 2022 Conference Proceedings Transport Research Arena (TRA Lisbon 2022),14th-17th November 2022, Lisboa, Portugal, Elsevier B.V. , 2023, p. 4041-4048Conference paper (Refereed)
    Abstract [en]

    The demand for railway service facilities in Europe has been rapidly increasing, prompting for more conflicts in capacity requests by railway undertakings. In Sweden, many of these facilities do not have any automatic monitoring possibilities and the infrastructure manager does not have accurate or real-time information about vehicles occupying the tracks. This introduces challenges in having efficient capacity utilization in such facilities. This paper proposes a framework for capacity allocation for facilities which are currently unmonitored in general and for railway yards in specific. The framework is proposed upon abessment of the feasibility of emerging technologies in monitoring railway service facilities, as well as evaluating the current capacity allocation process and the suitability of different pricing principles as a basis for a charging scheme for capacity reservation.

  • 348.
    Almqvist, Andreas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Simervir, Sandhu
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Trafikinformation i realtid i samband med vägarbete2012Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this report, we have explained the problems that may occur with today's technology and what possible solutions to improve with time. With the help of the Swedish Transport Administration, we have implemented this thesis.

    We got the clear directions from the Swedish Transport Administration regarding purpose of this thesis. This made it easy for us to delineate our work after the guideline that was definer.

    The study's purpose was to try to understand why you can´t give out the relevant traffic information. Today we have the technology create a well smooth operation system. A system where you can easily get real-time information related to traffic, road works and obstructions.

    In this report we have summarized all the navigation system that you could use as a road user. We have done an analysis of how other countries give out their traffic information and how good they are against the Swedish traffic information system.

    For our thesis we have used various of different reports and interviews. The interviews have been with people who have knowledge in the field. We have also used numerous websites to gather information.

    Recommendations for the thesis will be described through five themes. In this report, we have conducted a variety of interviews that we have compiled for themes. Themes were designed for what we felt was most relevant from the interviews. Our themes are a mirror image of what we thought was the most relevant part in our thesis.

     

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  • 349.
    Almqvist, David
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management, Building and Real Estate Economics.
    Sjölund, Emil
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management, Building and Real Estate Economics.
    Värdering av kommersiella fastigheter: Problem på en illikvid marknad2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    I denna rapport har vi valt att kritiskt granska fastighetsvärderingar på en illikvid marknad. Dels i fråga om metodval, dels om det föreligger någon form av systematisk felkälla och till sist om det råder oenighet kring tillämpningen av IFRS definition av verkligt värde. Kassaflödesmodellen är den idag vanligast förekommande värderingsmetoden och ger goda möjligheter till fastighetsspecifika justeringar under kalkylperioden. Vår uppfattning är dock att metoden endast ger sken av noggrannhet då kassaflödet ändå normeras tämligen slentrianmässigt samt att osäkerheten i direktavkastningskrav på en illikvid marknad är av överordnad betydelse. Vidare undersöker vi ifall det finns systematiska avvikelser i fastighetsvärderingar. Detta gör vi genom att undersöka korrelationen mellan de bedömda värdena på fastighetsmarknaden och aktiemarknaden. Den korrelation vi kan påvisa tyder på att fastighetsmarknaden lider av fenomenet valuation smoothing. IFRS har i sitt regelverk IAS 40 en tydlig definition på en fastighets verkliga värde som noterade bolag enligt lag är skyldiga att följa i sin redovisning. Vi jämförde de årliga bedömda värdeförändringar mellan fem noterade fastighetsbolag sinsemellan och såg en tydlig skillnad. Vid en närmare analys visar det sig att bolag med högre andel internvärdering av fastighetsbeståndet har en större spridning på sina värdeförändringar sett över tid. Orsaken till detta är svår att bevisa men problematiken kring att bolag som själva värderar sitt bestånd eventuellt påverkar värderingarna av fastigheterna tål att belysas.

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  • 350.
    Almqvist, Ludvig
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Groundwater investigation at Storsudret, Gotland2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sweden have faced decreasing groundwater storage with critical low groundwater levels for several years. Gotland is one example with issues of providing freshwater due to the low groundwater levels. These circumstances can be related to impacts caused by early agriculture development, an increased demand of freshwater and climate change. There is a need in this region to increase the groundwater storage to ensure enough freshwater. The aim of the study is to increase freshwater storage. Digital geographical information system (GIS) was chosen as a tool in this study in order to cover large geographical areas.  The study was divided into two parts, with focus to determine hydrological and hydrogeological conditions and to identify suitable areas where groundwater storage could be increased. The first part studied: specific capacity, groundwater storage, groundwater balance and topographic wetness index. The second part locked at four methods to increase freshwater storage: Lakes, controlled drainage, wetland and subsurface dam. The result tells us that lakes have the potential to provide freshwater for the municipal distribution network. The controlled drainage method has the ability reduce the outflow of surface water and to increase the groundwater infiltration. Earlier drained wetland areas was identified which could serve as freshwater storage. Suitable areas for subsurface dams were identified. They could work as a large groundwater storage as a decentralized system with the ability to provide groundwater for wells that are spread out. However the identified areas for each methods needs further investigations in more detail to determine the accuracy of the results.

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