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  • 301.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Jelagin, Denis
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Investigation of the asphalt mixture morphology influence on its ageing susceptibility2015In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 48, no 4, p. 987-1000Article in journal (Refereed)
    Abstract [en]

    The main objective of this study is to investigate the influence that asphalt mixture morphology aspects have on its overall ageing behavior. Since mixture morphology is controllable, having insight into how the various morphological parameters influence the mixture’s long-term behavior can be of great value to optimize its design, regardless of the individual material properties. To do so, this study is utilizing a new framework to characterize the combined effect of aggregate packing, average air void size, porosity and level of compaction on ageing for a large set of data from different sources of field compacted and laboratory produced asphalt mixtures. The paper also hypothesizes about the mechanisms that lay behind the found influences and how thus mixture design improvements can be made. From all the investigated cases, it was found that the framework can be used to optimize the durability performance of asphalt mixtures. It was also observed that prediction of ageing behavior without considering the influence of mixture morphology may lead to erroneous conclusions and non-optimal mix design.

  • 302.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Jelagin, Denis
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Evaluation of the low temperature cracking performance of asphalt mixtures utilizing HMA fracture mechanics2013In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 47, p. 594-600Article in journal (Refereed)
    Abstract [en]

    In the present study, the low temperature cracking performance of asphalt mixture has been investigated numerically and experimentally. To do so, the HMA thermal fracture model has extended by including fracture energy threshold and non-linear thermal contraction coefficient. This extended model is capable to predict thermally induced stress and fracture temperature, which is validated with experimental results obtained from three different types of asphalt mixtures. From the parametric study, it was observed that understanding the influence of thermal contraction coefficient, the cooling rate and the creep compliance parameters can make a significant contribution to the material's sustainability. From the analysis, it was found that this extended model can be utilized to evaluate the low temperature cracking performance of asphalt mixtures and capable to provide correct ranking. Interestingly, non-linear thermal contraction coefficient gave much better prediction than linear approach.

  • 303.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Jelagin, Denis
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Atomic Force Microscopy to Characterize the Healing Potential of Asphaltic Materials2012In: Atomic Force Microscopy - Imaging, Measuring and Manipulating Surfaces at the Atomic Scale / [ed] Victor Bellitto, InTech, 2012, p. 209-230Chapter in book (Refereed)
  • 304.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Jelagin, Denis
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Micro-Mechanical Investigation of Low Temperature Fatigue Cracking Behaviour of Bitumen2012In: 7th RILEM International Conference on Cracking in Pavements: Mechanisms, Modeling, Testing, Detection and Prevention Case Histories / [ed] Scarpas, A.; Kringos, N.; Al-Qadi, I.; Loizos, A., Springer Netherlands, 2012, p. 1281-1290Conference paper (Refereed)
    Abstract [en]

    In an effort to understand the effect of low temperature fatigue cracking, atomic force microscopy (AFM) was used to characterize the morphology of bitumen. In addition, thermal analysis and chemical characterization was done using differential scanning calorimetry (DSC) and thin-layer chromatography/flame ionization detection (TLC/FID), respectively. The AFM topographic and phase contrast image confirmed the existence of bee-shaped microstructure and different phases. The bitumen samples were subjected to both environmental and mechanical loading and after loading, micro-cracks appeared in the interfaces of the bitumen surface, confirming bitumen itself may also crack. It was also found that the presence of wax and wax crystallization plays a vital role in low temperature cracking performance of bitumen.

  • 305.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Wallqvist, Viveca
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Micromechanical investigation ofphase separation in bitumen bycombining atomic force microscopywith differential scanning calorimetryresults2013In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 14, no S1, p. 25-37Article in journal (Refereed)
    Abstract [en]

    The thermo-rheological behaviour of bitumen depends largely on its chemical structure and intermolecular microstructures. Bitumen is a complex mixture of organic molecules of different sizes and polarities for which the micro-structural knowledge is still rather incomplete. Knowledge at that level can have great implications for behaviour at a larger scale and will help to optimise the bitumen in its production stage. The present study is focused on understanding the fundamental mechanisms behind the micro-structural phase appearance and the speed or mobility at which they change. To do so, atomic force microscopy was utilised at different temperatures to investigate the phase separation behaviour for four different types of bitumen and co-relate it with the differential scanning calorimetry measurements. Based on the experimental evidences, it was found that the observed phase separation is mainly due to the wax/paraffin fraction presence in bitumen and that the investigated bitumen behaves quite differently. Recommendations are made to continue this research into qualitative information to be used on the asphalt mix design level.

  • 306.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Micro-scale investigation of oxygen diffusion on bitumen surfaces2014In: Asphalt Pavements - Proceedings of the International Conference on Asphalt Pavements, ISAP 2014, CRC Press, 2014, Vol. 1, p. 935-942Conference paper (Refereed)
    Abstract [en]

    This study investigates the evolution of microstructures due to oxygen diffusion on bitumen surface and its effect on bulk properties utilizing Atomic Force Microscopy (AFM) and Differential Scanning Calorimetry (DSC). The bitumen specimens were conditioned in four different modes: both light and air, only air but no light, only light but no air and neither light nor air, for 15 and 30 days. From the AFM investigation after 15 and 30 days of conditioning period, it was found that the percentages of microstructure on the surface reduced with ageing. The DSC heating scan showed that the amount of wax remains constant even after the systematic conditioning. Interestingly, during the cooling cycle, crystallization of wax molecules started earlier for the oxidized specimens than the non-oxidized one. The analysis of the obtained results indicated that the oxidation created a thin film upon the exposed surface, which acts as a barrier and creates difficulty for the wax induced microstructures to float up at the surface. From the DSC analysis, it can be concluded that the oxidation product induced impurities in the bitumen matrix, which acts as a promoter in the crystallization process.

  • 307.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Microscale investigation of thin film surface ageing of bitumen2014In: Journal of Microscopy, ISSN 0022-2720, E-ISSN 1365-2818, Vol. 254, no 2, p. 95-107Article in journal (Refereed)
    Abstract [en]

    This paper investigates the mechanism of bitumen surface ageing, which was validated utilizing the atomic force microscopy and the differential scanning calorimetry. To validate the surface ageing, three different types of bitumen with different natural wax content were conditioned in four different modes: both ultraviolet and air, only ultraviolet, only air and without any exposure, for 15 and 30 days. From the atomic force microscopy investigation after 15 and 30 days of conditioning period, it was found that regardless the bitumen type, the percentage of microstructure on the surface reduced with the degree of exposure and time. Comparing all the four different exposures, it was observed that ultraviolet radiation caused more surface ageing than the oxidation. It was also found that the combined effect was not simply a summation or multiplication of the individual effects. The differential scanning calorimetry investigation showed that the amount of crystalline fractions in bitumen remain constant even after the systematic conditioning. Interestingly, during the cooling cycle, crystallization of wax molecules started earlier for the exposed specimens than the without exposed one. The analysis of the obtained results indicated that the ageing created a thin film upon the exposed surface, which acts as a barrier and creates difficulty for the wax induced microstructures to float up at the surface. From the differential scanning calorimetry analysis, it can be concluded that the ageing product induced impurities in the bitumen matrix, which acts as a promoter in the crystallization process.

  • 308.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Numerical study on the effect of mixture morphology on long-term asphalt mixture ageing2015In: The international journal of pavement engineering, ISSN 1029-8436, E-ISSN 1477-268X, Vol. 16, no 8, p. 710-720Article in journal (Refereed)
    Abstract [en]

    Asphalt mixtures with similar percentages of air voids can have different morphologies and can age differently. Prediction of ageing behaviour without considering the influence of mixture morphology may thus lead to erroneous conclusions and non-optimal mix design. This article investigates the long-term field ageing of asphalt mixtures by incorporating mixture morphology. For this, a computational analysis on diffusion-reaction process has been conducted by implementing fundamental mechanism of ageing and conducting a parametric sweep of the morphology. To investigate the ageing gradient along the depth of asphalt mixture, diffusion controlled oxidative ageing on one dense and one open-graded field core was investigated. The proposed model based on the mixture morphology information was able to predict the aged viscosity better than the existing model. As mixture morphology is controllable, having insight into how the morphology parameter influences the mixture's ageing susceptibility can be of great value to its design.

  • 309.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Towards a Multi-scale Framework to Optimize Ageing Resistance of Asphaltic Materials2013In: Multi-Scale Modeling and Characterization of Infrastructure Materials: Proceedings of the International RILEM Symposium Stockholm, June 2013 / [ed] Niki Kringos, Björn Birgisson, David Frost, Linbing Wang, Springer Netherlands, 2013, , p. 434p. 285-295Conference paper (Refereed)
    Abstract [en]

    This paper describes an ongoing research project that is aiming at developing a comprehensive multi-scale approach to optimize the ageing resistance of asphaltic mixtures. In this, ageing has been focused on oxidative ageing, but allows future extension to other ageing mechanisms. The developed framework considers three different scales: the nano, micro and meso-scale which are defined as the bitumen phase, the mastic phase and the mixture phase, respectively. In nano-scale, atomic force microscopy and calorimetry are coupled to each other to give insight into how bitumen phase separation evolves and the mobility of microstructure changes with temperature and ageing. On the micro-scale, the energy dissipation as a function of ageing is measured and coupled to the phase behavior information from the nano-scale. On the meso-scale a morphology framework is defined, capable of identifying the dominant mixture morphology parameters that control mixture performance under ageing conditions. By coupling the three scales, the dominant parameters that control ageing of asphaltic mixtures can be defined, modeled and analyzed and as such a tool is created that has the potential of enhancing the sustainability of asphaltic mixtures.

  • 310.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Tasdemir, Yuksel
    Bozok Univ, Yozgat, Turkey .
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Evaluation of fracture and moisture damage performance of wax modified asphalt mixtures2012In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 13, no 1, p. 142-155Article in journal (Refereed)
    Abstract [en]

    In this study the fracture and moisture damage characteristics of wax modified asphalt mixtures were evaluated. Two types of commercial waxes (FT-paraffin and Asphaltan B) were added to bitumen of penetration grade 70/100. Using this wax modified and unmodified bitumen; total 48 specimens were produced from two sources of aggregates and two levels of gradation. Bitumen properties were determined by conventional test methods, Dynamic Shear Rheometer (DSR) and Bending Beam Rheometer (BBR) testing. Thermal Stress Restrained Specimen Test (TSRST) was used to evaluate low temperature cracking resistance and cracking behavior of asphalt mixture was investigated at 0 degrees C using Superpave Indirect Tensile Test (IDT). The influence of wax on the asphalt mixture resistance to cracking and moisture damage performance has been evaluated using Hot Mix Asphalt (HMA) fracture mechanics and Superpave IDT test results. The addition of FT-paraffin and Asphaltan B showed better cracking and moisture damage resistance of the asphalt mixture compared to unmodified mixture, but FT-paraffin showed the largest effect on cracking resistance while Asphaltan B showed highest resistance to moisture damage. In BBR test results, mixtures modified with FT-paraffin showed lower limit m value (LmT) which implies minor negative effect in stress relaxation. However, according to TSRST results, the mixtures with both waxes had nearly same fracture temperature as mixture with unmodified bitumen.

  • 311.
    Das, Prabir Kumar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Tasdemir, Yuksel
    Bozok University, Engineering and Architecture Faculty.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Low temperature cracking performance of WMA with the use of the Superpave indirect tensile test2012In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 30, p. 643-649Article in journal (Refereed)
    Abstract [en]

    Low temperature cracking of wax modified bitumen and asphalt mixtures were studied using the Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR), Superpave IDT and Thermal Stress Restrained Specimens Test (TSRST). Two types of commercial waxes (FT-paraffin and Asphaltan-B) were added to 70/100 penetration grade bitumen. Hot Mix Asphalt (HMA) fracture mechanics was used to determine fracture parameters. Master curves obtained from DSR and BBR test results showed stiffening effect due to wax additive at low temperature. The analysis of covariance was performed using a General Linear Model (GLM) on the Superpave IDT test results for Energy Ratio (ER) by using SPSS (Statistical Program for Social Sciences). Statistical analysis of Superpave IDT results showed a minor negative effect of wax modification at lower temperatures. Statistical analysis also showed that fracture parameters are highly temperature dependent and the two types of aggregate used did not play any significant role in low temperature cracking performance. Results obtained from TSRST tests indicate wax modification has a minor negative effect in low temperature cracking performance of asphalt mixtures.

  • 312.
    Das, Prabir
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Tasdemir, Y.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    LOW TEMPERATURE CRACKING PERFORMANCE OF WAX MODIFIED BITUMEN AND MIXTURE2011Conference paper (Refereed)
    Abstract [en]

    The road construction phase is one of the source of emissions (greenhouse gases), which causes climatic changes. To decrease this emission and energy consumption, asphalt industry is getting more aware of the warm mix asphalt (WMA) technology as it reduces the mixing and compaction temperature. There are several types of additives generally used for producing WMA such as: Fischer-Tropsch (FT) paraffin, Asphaltan B, Aspha-min, Evotherm etc. Fatigue and rutting resistance of asphalt mixtures could be increased by using WMA mixtures. On the other hand, the behavior of WMA mixtures in low temperature cracking is not completely clear yet. The main objective of this paper is to study the effect of commercial wax on low temperature cracking with the help of fracture mechanics.

    In this study, bitumen was modified with 4% Asphaltan B as a WMA additive. Bitumen properties were determined by conventional test methods, dynamic mechanical analysis and bending beam rheometer test whereas the mixture properties investigated by Superpave InDirect Tensile (IDT) test device and Thermal Stress Restrained Specimen Test (TSRST). The similar results were obtained from both Superpave IDT and TSRST. According to the test results, the addition of wax shows a minor negative effect. This minor difference between modified and unmodified mixture is very small, so it could be within the test repeatability limit.

  • 313. Dawson, A
    et al.
    Numrich, A
    Lekarp, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Rutting in Granular Pavement Layers1998Conference paper (Refereed)
  • 314.
    de Palma, André
    et al.
    Ecole Normale Supérieure de Cachan.
    Engelson, Leonid
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS. KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis.
    Network market conduct with atomic and non-atomic players2012Conference paper (Refereed)
    Abstract [en]

    In a non-atomic network game, there is a continuum of selfish users, independently choosing routes from the origins to thedestinations of their trips. In the static version of the game, each link of the network is endowed by a continuous increasing costfunction of the total flow of agents on the link. It is well known that a Nash equilibrium when no user can decrease own route costby unilaterally changing their route exists and is generally less efficient than the system optimum. In the last decade, a considerableamount of literature was devoted to designing Stackelberg routing in order to reduce the cost of anarchy, i.e. the ratio between thetotal cost of Nash and the system optimum cost, see e.g. Harks (2011) for overview. Apart from the non-atomic users theStackelberg routing assumes an atomic player - a leader - that can unilaterally and consciously influence the cost for thenon-atomic users – the followers - by partially controlling their route choice for a fraction of users. It is usually assumed that thecontrolled users perceive the same cost on each link as the uncontrolled ones.In our paper, we assume that there are two types of agents, which have different cost functions. As an example of such situation,one could consider a continuum of cars and a fleet of trucks. Indeed, the truck speed is normally lower than that of the cars and isless influenced by the congestion. Moreover, the truck route choice may be controlled by a common agency that pursues a strategyof minimising the total cost forof truck (private agency) or the total cost for all vehicles (governmental agency). The costs of usingthe routes areis route specific and vehicle type specific and isare given as specified as a linear functions of the total number ofusers on the route. Each car is atomic and ignores the impact of his decision on congestion. On the contrary, the coordinator of thefleet may take into account the total congestion cost of the trucks and of the cars. We consider several market situations:Stackelberg equilibrium with trucks controlled by the private agency(Stackelberg), the social system optimum, the second-bestoptimum with trucks controlled by the governmental agency, as well as the benchmark (Nash) with no coordination at all. Despitethe simple formulation, all scenarios beside the Nash lead to non-convex minimisation problems. Each of these problems alwayshas a non-interior solution although interior solutions may exist too.Without the coordination, the trucks and the cars choose their routes according to the deterministic user equilibrium. In the socialoptimum, the total cost for cars and trucks is minimised, and it is almost always possible to obtain a non-interior solution withlower total cost than in the user equilibrium.In the network consisting of two identical (i.e. with similar cost functions) parallel routes the trucks cannot benefit from thecoordination and the Stackelberg equilibrium coincides with Nash equilibrium. However, if there are more trucks (car equivalents)than cars and if the car cost function is steeper than the truck cost function, then the governmental agency can improve the socialwelfare compared to the user equilibrium scenario. In this case, moving a truck from the route that accumulates all cars increasethe total cost for trucks but decreases the total cost for the whole collection of vehicles.If the two routes are not identical then the coordination of trucks may actually worsen the situation by reducing the cost for trucksbut increasing the cost for cars and the total cost compared to the Nash equilibrium. On the other side, the governmental agencycontrolling the trucks may decrease the total cost to a value which is lower than the total cost in the Nash equilibrium at the sametime increasing the cost for trucks.In the Stackelberg game, the fleet of trucks is coordinated in order to minimise their total cost. We show that there is always anon-interior solution. However, in the case of identical routes neither cars nor trucks benefit from the coordination of the truck fleetsince equilibrium and optimum coincides. SAY WHAT COULD HAPPEN IN A NON SYMETRIC Finally, in the second bestscenario we envisage, we assume that the trucks choose routes so that the total cost over all vehicles (cars and trucks) is minimised.In the symmetric case, but with different cost functions for trucks and for cars, we have shown that no benefit can be obtained bythe coordination if the number of cars exceeds the number of trucks. However, with more trucks than cars, there is always apossibility to improve the social welfare compared to the user equilibrium scenario. PROVIDE SOME HINT WHY HEREWe finally examine the coordination game, when two fleets of trucks are competingcompeting for what. And the so what?Add the reference that I asked you to add.

  • 315.
    Deckner, Fanny
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. NCC.
    Lidén, Märta
    Grontmij.
    Hintze, Staffan
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering. NCC.
    Viking, Kenneth
    Norconsult.
    Markvibrationer vid spontning för Karlstad teater2013In: Bygg & teknik, ISSN 0281-658X, no 1, p. 25-29Article in journal (Other academic)
  • 316.
    Deckner, Fanny
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Viking, Kenneth
    Norconsult.
    Hintze, Staffan
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Ground vibrations due to pile and sheet pile driving: prediction models of today2012In: Proceedings of the 22nd European Young Geotechnical Engineers Conference / [ed] Victoria Svahn and Tara Wood, Gothenburg: Swedish Geotechnical Society , 2012, p. 107-112Conference paper (Refereed)
    Abstract [en]

    As part of aconstruction work pile and sheet pile driving unavoidably generates vibrations.As of today construction works are often located in urban areas and along withsociety’s increasing concern of environmental impact the need for vibrationprediction prior to construction is of immediate interest. This study presents a review of the predictionmodels existing today. For prediction of ground vibrations from pile and sheetpile driving there are roughly three different types of models; empirical models,theoretical models and engineering models. A prediction model should bereliable in all cases where it is meant to be used. It is also important thatit is relatively easy to use and that the input data is easily obtained. Thisstudy concludes that, as of today, there is a lack of such a model. Today’smodels either lack in reliability or require great amounts of input data,knowledge and skills as well as time and money. The findings within this study constitutethe initial part of an on-going research project at the division of Soil- and RockMechanics at the Royal Institute of Technology in cooperation with the DevelopmentFund of the Swedish Construction Industry and NCC Construction Sweden.

  • 317. Den Hengst, Marielle
    et al.
    Bekebrede, Geertje
    Meijer, Sebastiaan
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Training Adjunct Commissionaires of Police in an Open Simulation: Methodological Challenges from a Politically Sensitive Case2012In: Policing: A Journal of Policy and Practice, ISSN 1752-4512, E-ISSN 1752-4520Article in journal (Refereed)
  • 318.
    Deng, Qichen
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    A Constant Spacing Policy for Heavy-Duty VehiclePlatoon Disaggregation at Highway Off-RampManuscript (preprint) (Other academic)
    Abstract [en]

    Platooning heavy-duty vehicles (HDVs) on highways using cooperative adaptive cruise control (CACC) can significantly reduce fuel consumption and improve traffic throughput.HDVs operating with small inter-vehicle distances reduce aerodynamic resistance considerably. However, HDV platoons can also have negative impacts on traffic flow when they hinder lane changing at highway off-ramps. This study investigates whether disaggregation of HDV platoons benefits traffic flow at highway off-ramps. A modified constant spacing policy is applied forHDV platoon disaggregation. The feasible region of the CACCparameters is derived based on an analysis of asymptotic stability, driving safety, and HDV acceleration and braking capabilities.The proposed HDV platoon disaggregation strategy at highway off-ramps is implemented and simulated in a microscopic traffic simulation package. According to the simulation outcomes, a disaggregation of HDV platoons at off-ramps leads to significant average speed improvements at high traffic flow rates.

  • 319.
    Deng, Qichen
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    A General Simulation Framework for Modeling and Analysis of Heavy-Duty Vehicle Platooning2016In: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 17, no 11, p. 3252-3262Article in journal (Refereed)
    Abstract [en]

    Platooning heavy-duty vehicles (HDVs) on a highway is a method for improving energy and transport efficiency. On one hand, HDV platoon driving in small intervehicle distances could increase highway capacity; on the other hand, HDVs traveling in small intervehicle distances experience significant air-drag reduction and, therefore, improve fuel efficiency. However, although the majority of research has been conducted on the development of platoon systems, very few studies have focused on quantification of the impacts of HDV platooning on traffic flow. This paper initializes a simulation framework to facilitate the study of HDV platooning and establishes the corresponding concept and operations. The longitudinal driving behaviors of HDV platoons are modeled in detail, considering the acceleration capability of an HDV. The proposed framework is applied on three experimental cases: the first case is to study the impacts of HDV platooning on traffic flow and the second and third cases are about the influence of traffic on HDV platoon formation. In the first case, simulation outcomes show that the increasing percentage of HDV platooning in traffic flow generally results in more dramatic improvements on traffic efficiency, while preserving traffic safety for passenger vehicles. In the second and third cases, for the HDV platoon formation, deceleration of the first HDV to a low speed during platoon formation will increase the formation time to a large extent in medium and heavy traffic.

  • 320.
    Deng, Qichen
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    A General Simulation Framework for Modeling andAnalysis of Heavy-Duty Vehicle PlatooningManuscript (preprint) (Other academic)
    Abstract [en]

    Platooning heavy-duty vehicles (HDVs) on highway is a method of improving energy and transport efficiency. On the one hand, HDV platoon driving in small inter-vehicle distances could increase highway capacity; on the other hand, HDVs traveling in small inter-vehicle distances experience significant air -drag reduction and therefore, improve fuel efficiency. However, the majority of research has been conducted on the development of platoon system, very few studies have focused on quantification of the impacts of HDV platooning on traffic flow. This paper initializes a simulation framework to facilitate the study of HDVplatooning and establishes corresponding concept and operations.The longitudinal driving behaviors of HDV platoons is modeled in detail considering the acceleration capability of HDV. The proposed framework is applied in three experimental cases, the first case is to study the impacts of HDV platoons on traffic flow, and the second and third cases are about the influence of traffic on HDV platoon formation. In the first case, simulation outcomes show that increasing percentage of HDV platooning in traffic flow generally results in more dramatic improvements in traffic efficiency while preserving traffic safety for passenger vehicles; in the second and third cases, for the HDV platoon formation, deceleration of the first HDV in low speed during platoon formation will increase the formation time to a large extent in medium and heavy traffic.

  • 321.
    Deng, Qichen
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Heavy-Duty Vehicle Platooning: Modeling and Analysis2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Coupled with the growth of world economy, the demand for freight transport has escalated and will continue to do so. As the traffic intensity increases, the pressure on infrastructure, energy usage and environment becomes higher than ever. Meanwhile, the number of traffic accidents is also increasing year by year as a result. Heavy-duty vehicle (HDV) platooning makes a group of HDVs driving closely after each other.It is one potential solution to improve transport efficiency, traffic safety and fuel economy. Even though there have been extensive studies on the platooning system and corresponding fuel saving, some of the research areas, such as coordination strategies of platooning, platoon operations and the impacts of HDV platooning on trafficflow are still left open. Under a futuristic scenario where a large number of HDVswill be operating in one or several platoons on highway, how to group HDVs intoa platoon and how to select spacing policies for HDV platooning are essential forautomobile manufacturers, fleet operators and transport planners. Therefore, theformation strategies and operations of HDV platoons, as well as the impacts of HDVplatooning on traffic flow have to be carefully investigated.

    This thesis presents contributions to the modeling of HDV platooning and simulationof HDV platoon operations. The focus lies mainly on analytical formulation ofspeed-density relation of mixed traffic flow and development of simulation frameworkfor study of HDV platooning. On the one hand, a three-regime speed-density relationis proposed to describe the mixed traffic flow consisting of HDVs and passengercars. The proposed speed-density relation incorporates percentage of HDVs, trafficdensity and spacing policy of HDV platoons as input variables and delivers aggregatehighway velocity as output. By comparing the traffic throughput of no HDV platooningscenario, grouping HDVs into platoon using constant vehicle spacing policy orconstant time gap policy results in significant improvement in highway capacity. On the other hand, a simulation framework is developed for implementation of differentHDV platoon operations. The platoon formation of two HDVs and disaggregation ofa five-HDV platoon at off-ramp are simulated on a two-lane highway. The simulationoutcomes show that HDV platoon formation is more favorable in light and mediumtraffic; disaggregation of a long HDV platoon at off-ramp improves the averagespeed of passenger vehicles considerably at high traffic flow rate.

  • 322.
    Deng, Qichen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Boughout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    The Impacts of Heavy-Duty Vehicle Platoon Spacing Policy on Traffic FlowManuscript (preprint) (Other academic)
    Abstract [en]

    Spacing policy of heavy-duty vehicle (HDV) platoons determines the inter-vehicle distance between HDVs in steady state. It plays an important role in traffic throughput. For example, an HDV platoon with small spacing policies saves space on the highway so that it can accommodate more vehicles. Therefore, the traffic efficiency and highway capacity may be improved by applying small spacing policies on HDV platoons. Conversely, an HDVplatoon with larger spacing policies requires more space on highways and thus has a negative impact on capacity.This paper specifically focuses on two commonly used spacing policies in HDV platooning, constant vehicle spacing (CVS) and constant time gap (CTG) and investigates respective impacts on traffic flow. The speed-density relation of mixed traffic flow is formulated as a function of traffic density, the percentage of HDVs on highway and spacing policy of HDV platoon. In order to investigate the effects of HDV platooning to vehicle interaction, the speed-density relation is derived from car-following model. Numerical results show that HDV platooning with CVSpolicy yields the most significant improvement in highway capacity, compared with no HDV platooning scenario and HDV platooning with CTG policy. However, it has worse performance in heavily congested traffic flows thanCTG policy. A mixed CVS-CTG policy is therefore proposed in this study, in order to combine the benefits fromCVS and CTG policies to traffic flow. This mixed spacing policy could be a promising alternative to the single spacing policy.

  • 323.
    Deng, Qichen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    A fast algorithm for planning optimal platoon speeds on highway2014In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 19, p. 8073-8078Article in journal (Refereed)
    Abstract [en]

    To meet policy requirements on increased transport energy efficiency and reduced emissions, smart control and management of vehicles and fleets have become important for the development of eco-friendly intelligent transportation systems (ITS). The emergence of new information and communication technologies and their applications, particularly vehicle-to-vehicle and vehicle-to-infrastructure communication, facilitates the implementation of autonomous vehicle concepts, and meanwhile serves as an effective means for control of vehicle fleet by continuously providing support and guidance to drivers. While convoy driving of trucks by longitudinal automation could save 5-15% of fuel consumption due to the reduction of airdrag resistance, this study attempts to investigate the energy saving potential of truck platoons by intelligent speed planning. Assuming that real-time traffic information is available because of communication, an efficient speed control algorithm is proposed based on optimal control theory. The method is faster than the conventional dynamic programming approach and hence applied in the study to analyze energy saving potential of simple platoon operations including acceleration and deceleration. The numerical result shows significant improvement on energy saving due to speed planning during platooning. It can be further applied for more complex platooning operations.

  • 324.
    Deng, Qichen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Fast Algorithm for Planning Optimal Platoon Speeds on Highway2014In: Proceedings of the 19th IFAC World Congress, 2014, International Federation of Automatic Control , 2014Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    To meet policy requirements on increased transport energy eciency and reduced emissions, smart control and management of vehicles and eets have become important for the development of eco-friendly intelligent transportation systems (ITS). The emergence of new information and communication technologies and their applications, particularly vehicle to vehicle and vehicle-to-infrastructure communication, facilitates the implementation of autonomous vehicle concepts, and meanwhile serves as an eective means for control of vehicle eet by continuously providing support and guidance to drivers. While convoy driving of trucks by longitudinal automation could save 5-15% of fuel consumption due to the reduction of airdrag resistance, this study attempts to investigate the energy saving potential of truck platoons by intelligent speed planning. Assuming that real-time trac information is available because of communication, an ecient speed control algorithm is proposed based on optimal control theory. The method is faster than the conventional dynamic programming approach and hence applied in the study to analyze energy saving potential of simple platoon operations including acceleration and deceleration. The numerical result shows signicant improvement on energy saving due to speed planning during platooning. It can be further applied for more complex platooning operations.

  • 325. Dham, A.
    et al.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Boyd, A.J
    McGill University.
    The Determination of Bound Water in Waste Phosphatic Clay2009In: Research Letters in Materials Science, ISSN 1687-6822Article in journal (Refereed)
    Abstract [en]

    Phosphatic clay is a by-product of phosphate strip mining, particularly in Florida, USA. This waste material occupies about 100000 acres of land which could be utilized for other causes. Thus, its use as an alternating cementing material for the addition into the mixing matrix of cement paste and concrete to yield higher strength would be profitable for both materials involved. But the biggest drawback faced is that the phosphatic claypossesses high water holding capacity. The water is thus not available for mixing purposes when added to cement paste and concrete and is thus known as bound water. It is therefore essential to determine the amount of bound water to phosphatic clay which shall not be available for the hydration reaction of cement in cement paste and concrete.

  • 326. Dham, M.
    et al.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    The Evaluation of the Addition of Phosphatic Clay in Cement Paste and Concrete2011In: International Journal of Materials Engineering and Technology, ISSN 0975-0444, Vol. 5, no 2, p. 101-114Article in journal (Refereed)
    Abstract [en]

    Phosphatic clay is a by-product of the phosphate strip mining industry, and disposal is particularly a problem in Florida, USA. This waste material occupies about 100,000 acres of land which could be utilized for other causes. Thus, its potential utilization as a supplementary cementing material added to the cement paste matrix of concrete to produce higher strength would be beneficial for both the mining and construction industries. The waste clay contains calcium montmorillonite, which should react pozzolanically with the calcium hydroxide produced from the hydration reactions to produce additional C-S-H, the building block of concrete systems, and thus enhancing the mechanical properties of cement paste and concrete. The effects of phosphatic clay addition on the bulk properties of cement paste and concrete are investigated, and it is shown that moderate additions (5% replacement of cement by mass) can indeed produce a significant increase in strength. The effect of the modified paste on the interfacial transition zone in concrete is also observed.

  • 327.
    Dharmowijoyo, Bayu Endrayana
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Susilo, Yusak O
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Karlström, Anders
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, System Analysis and Economics.
    Adiredja, L. S.
    Collecting a multi-dimensional three-weeks household time-use and activity diary in the Bandung Metropolitan Area, Indonesia2015In: Transportation Research Part A: Policy and Practice, ISSN 0965-8564, E-ISSN 1879-2375, Vol. 80, p. 231-246, article id 1641Article in journal (Refereed)
    Abstract [en]

    This paper describes a comprehensive panel data collection and analysis at household level, including detailed travel behaviour variables and comprehensive in-home and out-of-home activities, individual cognitive habits and affective behaviours, the rate of physical activity, as well as health related quality of life (QoL) information in the Bandung Metropolitan Area (BMA) of Indonesia. To our knowledge, this is the first attempt to collect an individual's activity diary over an extended period as it captures the multi-tasking activities and multidisciplinary factors that underlie individual activity-travel patterns in a developing country. Preliminary analyses of the collected data indicate that different beliefs, anticipated emotions, support and attachment to motorised modes significantly correlate with different groups of occupation, gender, age, activity participation, multi-tasking activities, and physical health, but not with different social and mental health. This finding highlights the reason why implementing car reduction policies in Indonesia, without breaking or changing the individual's habits and influencing his/her attitudes have not been fruitful. The results also show that endorsing more physical activities may result in a significant reduction in the individual's motorised mode use, whilst individuals who demonstrate a tendency to use their spare time on social activities tend to have better social health conditions. Furthermore, undertaking multi-tasking out-of-home discretionary activities positively correlates with better physical health. All these highlight the importance of properly understanding and analysing the complex mechanisms that underlie these fundamental factors that shape individual daily activity-travel patterns in developing countries. This type of multidisciplinary approach is needed to design better transport policies that will not only promote better transport conditions, but also a healthier society with a better quality of life.

  • 328. Dharmowijoyo, Dimas B. E.
    et al.
    Susilo, Yusak
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, System Analysis and Economics.
    Karlström, Anders
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, System Analysis and Economics.
    Relationships among discretionary activity duration, its travel time spent and activity space indices in the Jakarta Metropolitan Area, Indonesia2016In: Journal of Transport Geography, ISSN 0966-6923, E-ISSN 1873-1236, Vol. 54, p. 148-160Article in journal (Refereed)
    Abstract [en]

    This study examines the interdependencies among an individual's time allocation for different activities and the travel time spent on a given day, socio-demographic and built environment variables on these in-home and out of-home discretionary activities time duration, and how interaction of those variables on discretionary activities time duration influences an individual's activity space indices in the Jakarta Metropolitan Area (JMA), Indonesia. The 3SLS model and the 2004 SITRAMP household travel survey were used to achieve this objective. The results show that the time allocation for certain discretionary activities significantly influences the time allocation for other discretionary activities. Workers, students and non-workers have different complex mechanisms pertaining to how they allocate time across different activities and journeys. This unique trade-off mechanism gives an individual a unique distribution of activity locations and spatial movement patterns. This is observed via his/her activity space indices throughout time and space. For example, the estimation result shows that workers' and students' time-use allocation, activities participation and activity space indices are highly influenced by their engagement in mandatory activities. However, this is not the case for non-workers. Furthermore, the mandatory travel time variable has a stronger impact on an individual's discretionary activities time-use pattern than the duration of mandatory activities. This may lead to the argument that, in order to provide more opportunities and flexibilities among the JMA's workers and students for undertaking discretionary activities, travel time reduction policies can play more significant role in shaping the discretionary activity-travel patterns than reduction in working/school hour policies. Additionally, in-line with previous findings in developed countries, locating grocery shops closer to residential areas in the CBD and in suburban areas creates more opportunities for workers and students to spend more time on out-of-home maintenance activities; with a shorter travel time, especially on. Fridays.

  • 329. Dharmowijoyo, Dimas B. E.
    et al.
    Susilo, Yusak O.
    Karlström, Anders
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Analysing the complexity of day-to-day individual activity-travel patterns using a multidimensional sequence alignment model: A case study in the Bandung Metropolitan Area, Indonesia2017In: Journal of Transport Geography, ISSN 0966-6923, E-ISSN 1873-1236, Vol. 64, p. 1-12Article in journal (Refereed)
    Abstract [en]

    Using a panel regression model and a multidimensional three-week household time-use and activity diary, this study analyses the complexity of the day-to-day variability in individuals' activity-travel patterns by applying a multidimensional sequence alignment model. It is found that the variability between weekend and weekday pairs is much greater than between weekday-weekday pairs or weekend-weekend pairs. The variability of other household members' activity-travel patterns is found to significantly influence an individual's activity-travel patterns. The results also show that the variability in the activity-travel patterns of workers and students is greater when conducting a particular discretionary activity on weekdays. Due to performing discretionary activities more often and for longer, non-workers tend to have more predictable activity-travel patterns. Undertaking multitasking activities within different activities on weekdays significantly impacted the different degrees of variability in an individual's activity-travel patterns. Having different health and built environment characteristics also corresponds with different degrees of predictability of the activity-travel patterns, particularly in the worker/student case.

  • 330.
    Dharmowijoyo, Dimas B. E.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Susilo, Yusak O.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Karlström, Anders
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, System Analysis and Economics.
    Analysing the complexity of day-to-day individuals’ activity-travel pattern using Multi-dimensional Sequence Alignment Method: A case study in Bandung Metropolitan Area, IndonesiaManuscript (preprint) (Other academic)
  • 331.
    Dharmowijoyo, Dimas B. E.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis.
    Susilo, Yusak O.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis.
    Karlström, Anders
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis.
    Day-to-day interpersonal and intrapersonal variability of individuals' activity spaces in a developing country2014In: Environment and Planning, B: Planning and Design, ISSN 0265-8135, E-ISSN 1472-3417, Vol. 41, no 6, p. 1063-1076Article in journal (Refereed)
    Abstract [en]

    Using the SITRAMP dataset, which was collected in the Jakarta metropolitan area, Indonesia, over four consecutive days, this study examines day-to-day variability of individuals' activity spaces. The impact of individual heterogeneity and variability of transport network conditions on day-to-day variability of activity spaces is also investigated. Results show that individuals' activity spaces vary from day to day and between different individuals. The activity space of other household members was found to be the most significant factor influencing an individual's activity space. Against the common belief in developing countries that better traffic conditions make individuals travel farther, results show that higher road-network travel speed and better road surface conditions within the home zones actually encourage individuals to visit a more compact set of activity locations and/or visit fewer activity locations. Smoother road surface conditions and higher travel speeds within home zones also bring the centroid of activity locations closer to individuals' home locations. Furthermore, day-to-day variability analysis of individual activity spaces showed that weekday activity spaces are more compact than those at weekends. Moreover, it was found that students' activity spaces show most variability, while those of nonworkers have the lowest variability.

  • 332.
    Dharmowijoyo, Dimas B. E.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Susilo, Yusak O.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Karlström, Anders
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Day-to-day variability in travellers' activity-travel patterns in the Jakarta metropolitan area2016In: Transportation, ISSN 0049-4488, E-ISSN 1572-9435, Vol. 43, no 4, p. 601-621Article in journal (Refereed)
    Abstract [en]

    Using four consecutive days of SITRAMP 2004 data from the Jakarta metropolitan area (JMA), Indonesia, this study examines the interactions between individuals’ activity-travel parameters, given the variability in their daily constraints, resources, land use and road network conditions. While there have been a significant number of studies into day-to-day variability in travel behaviour in developed countries, this issue is rarely examined in developing countries. The results show that some activity-travel parameter interactions are similar to those produced by travellers from developed countries, while others differ. Household and individual characteristics are the most significant variables influencing the interactions between activity-travel parameters. Different groups of travellers exhibit different trade-off mechanisms. Further analyses of the stability of activity-travel patterns across different days are also provided. Daily commuting time and regular work and study commitments heavily shape workers’ and students’ flexibility in arranging their travel time and out-of-home time budget, leading to more stable daily activity-travel patterns than non-workers.

  • 333.
    Dharmowijoyo, Dimas B. E.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Susilo, Yusak O.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Karlström, Anders
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, System Analysis and Economics.
    On complexity and variability of individuals’ day-to-day discretionary activitiesManuscript (preprint) (Other academic)
  • 334.
    Dharmowijoyo, Dimas B. E.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Susilo, Yusak O.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Karlström, Anders
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, System Analysis and Economics.
    Relationships among discretionary activity duration, travel time spent and activity space indices in the Jakarta Metropolitan Area, IndonesiaManuscript (preprint) (Other academic)
  • 335.
    Dharmowijoyo, Dimas Bayu Endrayana
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    The complexity and variability of individuals' activity-travel patterns in Indonesia2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Considering an individual’s day-to-day variability of activity-travel patterns will provide a more complete description of how an individual behaves to adapt the changing constraints and resources on different days. Without this day-to-day variability understanding, the individual’s behaviour would not be fully grasped and any suggested policy, planning and development would not completely achieve their desired objectives. The day-to-day behaviour is a subject to an interaction between individual’s needs and time-space constraints. The availability of ‘external’ resources (e.g., disposable income, built environment accessibility, and access to different travel mode/s) gives more opportunities for some individuals to participate in certain activities and/or trips than others. The constraints do not only consider budget and time constraints, but also include how an individual associates with other individuals and materials, and complies with any given authorities’ rules and regulations. The needs-constraints interaction also unveils some endogeneities which may not be captured by microeconomic and attitude theories. Failing to understand these interactions will underestimate the individual’s complex decision making process for performing certain behaviour.

    The constraints are not solely about physical constraints and instrumental factors, such as travel mode availability, time and cost. It is also influenced by individual’s non-instrumental variables, such as motivation, volition and habits. Currently there is a lack of knowledge how these non-instrumental variables are interacting and influencing the constraints to shape the individual’s travel behaviour. The implementation of certain activity-travel policy which only focuses in giving more opportunities to an individual within time and space resources without considering an individual’s attitude and/or habit may not be well accepted and followed by member of public. Moreover, the integration also reveals how an individual puts different priority on different potential activities based on the how an individual allocates/does not allocate time in engaging certain activities when having strong commitment and intention. In addition, including an individual’s health condition in the analysis may help in coordinating certain public health related policy with activity-travel policy.

    This thesis includes six papers which investigated the factors described above. The first three papers investigated how activity participation and built environment variables which can represent individuals’ constraints explain the day-to-day variability of individuals’ behaviours. Furthermore, the fourth and fifth paper explored the interaction between individuals’ time-use and activity participation, subjective characteristics and health factors. Lastly, the sixth paper examined how the time-space constraints and health condition explain the degree of variability in individuals’ multi-facet and multi-dimensional activity-travel patterns using sequential alignment method.  

  • 336.
    Dharmowijoyo, Dimas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Susilo, Yusak
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Karlström, Anders
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS. KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis.
    The Day to Day Inter and Intra Personal Variability of Individual's Action Space in Developing CountryIn: Environment and Planning, B: Planning and Design, ISSN 0265-8135, E-ISSN 1472-3417Article in journal (Other academic)
  • 337.
    Dharmowijoyo, Dimas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Susilo, Yusak
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Karlström, Anders
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    The Day to Day Variability of Traveller's Activity Travel Pattern in The Jakarta Metropolitan Area2012In: TRB 93rd Annual Meeting Compendium of Papers, TRB , 2012, , p. 24Conference paper (Refereed)
    Abstract [en]

    Using four consecutive days of SITRAMP Data (2004) from the Jakarta Metropolitan Area (JMA), this study examines the interactions between individuals’ activity-travel pattern variables in the context of their daily constraints, resources and external opportunities. The results from our simultaneous equation modeling show that the observed individual’s activity-travel patterns are the result of the complex interactions between each individual’s activity-travel parameters, which vary from day to day. Some of the interactions are similar with the patterns produced by travelers from developed countries, while others are different. Household and individual characteristics are the most significant variables influencing the interactions among individual activity-travel patterns. Different groups of travelers have different trade-off mechanisms. Further analyses on the stability of the activity-travel patterns across different days are provided. Daily commuting time and regular work commitments heavily shape workers’ and students’ flexibility in arranging their travel time and out-of-home time budget, leading them to more stable daily activity-travel patterns than non-workers. The model also shows that highly unpredictable traffic significantly influences workers’ and students’ intra-personal variability in travel time, more so than any other variable.

  • 338. diBenedetto, H
    et al.
    delaRoche, C
    Baaj, A
    Pronk, A
    Lundström, R
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Fatigue of Bituminous Mixtures: Different Approaches and RILEM Group Contribution2003In: Proceedings of the PTEMB’03 Conference in Zurich (ed. M. Partl), 2003Conference paper (Refereed)
  • 339.
    Dinegdae, Yared H.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Onifade, Ibrahim
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Jelagin, Denis
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Mechanics-based Topdown Fatigue Cracking Initiation Prediction Framework for Asphaltic Pavements2015In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402, Vol. 16, no 4Article in journal (Refereed)
    Abstract [en]

    In this paper, a new mechanics-based top-down fatigue cracking analysis framework is presented for asphalt pavements. A new mixture morphology-based set of material sub-models is presented for characterising key mixture properties and their change over time. Predicting the load induced top-down fatigue crack initiation (CI) time by utilising comprehensive mixture properties creates the possibility of optimising the mixture morphology while taking into account its subsequent effect on long-term pavement performance. The new framework was calibrated and subsequently validated against a number of field pavement sections with varying traffic levels that are representative for current practices and which have a wide range in material properties. The framework accounts the change in key mixture properties due to ageing and mixture-healing effect on damage accumulation while determining the overall effect of design inputs on cracking performance. Model calibration and validation were achieved based on the healing potential of the asphalt mixture. It was found out that the CI predictions for all the sections are in general agreement with the observed performance in the field, thus giving credibility for the framework.

  • 340. Ding, Jing
    et al.
    Gao, Song
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Rahmani, Mahmood
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Huang, He
    Ma, Long
    Pereira, Francisco
    Ben-Akiva, Moshe
    Routing policy choice set generation in stochastic time-dependent networks: Case studies for Stockholm and Singapore2014Conference paper (Refereed)
    Abstract [en]

    Transportation systems are inherently uncertain due to the occurrence of random disruptions; meanwhile, real-time traveler information offers the potential to help travelers make better route choices under such disruptions. This paper presents the first revealed preference (RP) study of routing policy choice where travelers opt for routing policies instead of fixed paths. A routing policy is defined as a decision rule applied at each link that maps possible realized traffic conditions to decisions on the link to take next. It represents a traveler's ability to look ahead in order to incorporate real-time information not yet available at the time of decision. An efficient algorithm to find the optimal routing policy (ORP) in large-scale networks is presented, as the algorithm is a building block of any routing policy choice set generation method. Two case studies are conducted in Stockholm, Sweden and Singapore, respectively. Data for the underlying stochastic time-dependent network are generated from taxi Global Positioning System (GPS) traces through the methods of map-matching and non-parametric link travel time estimation. The routing policy choice sets are then generated by link elimination and simulation, in which the ORP algorithm is repetitively executed. The generated choice sets are first evaluated based on whether or not they include the observed GPS traces on a specific day, which is defined as coverage. They are then evaluated on the basis of adaptiveness, defined as the capability of a routing policy to be realized as different paths over different days. It is shown that using a combination of link elimination and simulation methods yield satisfactory coverage. The comparison to a path choice set benchmark suggests that a routing policy choice set could potentially provide better coverage and capture the adaptive nature of route choice. The routing policy choice set generation enables the development of a discrete choice model of routing policy choice, which will be explored in the second stage of the study.

  • 341. Ding, Jing
    et al.
    Gao, Song
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Rahmani, Mahmood
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Huang, He
    Ma, Long
    Pereira, Francisco
    Ben-Akiva, Moshe
    Routing Policy Choice Set Generation in Stochastic Time-Dependent Networks Case Studies for Stockholm, Sweden, and Singapore2014In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, no 2466, p. 76-86Article in journal (Refereed)
    Abstract [en]

    Transportation systems are inherently uncertain because of random disruptions; nevertheless, real-time information can help travelers make better route choices under such disruptions. The first revealed-preference study of routing policy choice is presented. A "routing policy" is defined as a decision rule applied at each link that maps possible realized traffic conditions to decisions to be made on the link next. The policy represents a traveler's ability to incorporate real-time information not yet available at the time of decision. Two case studies are conducted in Stockholm, Sweden, and in Singapore. Data for the underlying stochastic time-dependent network are generated from taxi GPS traces through map-matching and nonparametric link travel time estimation. An efficient algorithm to find the optimal touting policy in large-scale networks is first presented, which is a building block of any routing policy choice set generation method. The routing policy choice sets are then generated by link elimination and simulation. The generated choice sets are first evaluated on the basis of whether they include the observed traces on a specific day, or coverage. The sets are then evaluated on the basis of "adaptiveness," defined as the capability of a routing policy to be realized as different paths over different days. A combination of link elimination and simulation methods yields satisfactory coverage. The comparison with a path choice set benchmark also suggests that a routing policy choice set could potentially provide better coverage and capture the adaptive nature of route choice.

  • 342. Ding, Jing
    et al.
    Gao, Song
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Rahmani, Mahmood
    KTH.
    Pereira, Francisco
    Ben-Akiva, Moshe
    Latent-class routing policy choice model with revealed-preference data2015Conference paper (Refereed)
  • 343.
    Djoko, Emeric
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Evaluation of the feasibility of a new North-South metro line in Stockholm from an infrastructure and capacity perspective.2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    From a sustainability point of view, the development of Stockholm County both in terms of

    population and activities will induce a high demand for public transport needs in the coming

    decades. Several districts currently badly linked to the Stockholm rapid transit network will see

    a large increase of inhabitants and workplaces, like Hagastaden or Årstafältet. Therefore a new

    North-South high capacity and fast connection is needed between these areas and the rail

    network. This thesis will estimate the corridors and the infrastructure of this new line.

    Since another objective of the new North-South Metro line is to create an alternative to the

    existing radial network with all the lines merging to Stockholm Central station, this thesis will

    also evaluate how this new line will improve the robustness of the global public transport

    network in Stockholm region. That is, how the passenger loads on the other lines will be

    influenced by the new link as the aim is to decrease the load on the existing overcrowded

    stretches (e.g. around T-Centralen) and reduce travel times. Comparisons will be made between

    the different alternatives, with and without the new line, to evaluate the efficiency of the new

    line in terms of passenger load, travel time savings and economically

  • 344. Djukic, T.
    et al.
    Flötteröd, Gunnar
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Van Lint, H.
    Hoogendoorn, S.
    Efficient real time OD matrix estimation based on Principal Component Analysis2012In: Intelligent Transportation Systems (ITSC), 2012 15th International IEEE Conference on, IEEE , 2012, p. 115-121Conference paper (Refereed)
    Abstract [en]

    In this paper we explore the idea of dimensionality reduction and approximation of OD demand based on principal component analysis (PCA). First, we show how we can apply PCA to linearly transform the high dimensional OD matrices into the lower dimensional space without significant loss of accuracy. Next, we define a new transformed set of variables (demand principal components) that is used to represent the fixed structure of OD matrices in lower dimensional space. We update online these new variables from traffic counts in a novel reduced state space model for real time estimation of OD demand. Through an example we demonstrate the quality improvement of OD estimates using this new formulation and a so-called 'colored' Kalman filter over the standard Kalman filter approach for OD estimation, when correlated measurement noise is accounted due to reduction of variables in state vector.

  • 345. Drakos, C
    et al.
    Roque, R
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Effect of Measured Tire Contact Stresses on Near-Surface Rutting2001In: Transportation Research Record, Vol. 1764Article in journal (Refereed)
  • 346. Drescher, A
    et al.
    Kringos, Nicole
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    On the Behavior of a Parallel Elasto-Visco-Plastic Model for Asphaltic Materials2010In: Mechanics of materials (Print), ISSN 0167-6636, E-ISSN 1872-7743, Vol. 42, no 2, p. 109-117Article in journal (Refereed)
    Abstract [en]

    The paper considers a dissipation energy based elasto-visco-plastic constitutive modelformulated by coupling in parallel visco-elastic and elasto-plastic components, which has been developed at Delft University of Technology for the response prediction ofasphaltic materials. To discuss the various aspects of the model under different creep loads, a simplified one-dimensional analytical solution is derived. Three different analytical cases are treated: visco-elastic response, elasto-visco-plastic response in which plasticity develops during the loading and instantaneous plasticity. The analyses show that the interaction between the parallel visco-elastic and elasto-plasticcomponents of the model are an important aspect of the predictive capabilities of themodel. A case is derived in which short duration loading of the model could lead to aprediction of increasing strains during the unloading phase. Care should be taken when choosing the material parameters of the model to avoid this erroneous prediction. 

  • 347.
    Duarte, Joakim
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport planning, economics and engineering.
    Potentiella cyklister i Stockholm: Faktorer som påverkar benägenheten att cykla2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Städer som saknar infrastruktur och som har en låg befolkningsdensitet tycks ha en betydligt lägre andel cyklister. När fler personer cyklar blir cykeln ett naturligare inslag i stadstrafiken, vilket bl.a. medför att städer med fler cyklister generellt sett är säkrare att cykla i. Andra städer skiljer sig från Stockholm beträffande befolkningsmängd, existerande infrastruktur för cyklister och hur stor andel av alla resor som sker med cykel. Att jämföra andra städer med Stockholm är ett problem på grund av dessa skillnader. Att förutse en förändring i andelen cyklister utifrån en jämförelse städer emellan blir därför svår.

    En litteraturstudie med målet att identifiera och värdera aspekter som påverkar cyklister och valet att börja cykla genomförs. Betydelsen av infrastruktur undersöks och resultatet visar att infrastrukturen är av stor vikt och att brister i infrastrukturen leder till att få kan tänka sig att börja cykla. Bristande infrastruktur leder till att viktiga förutsättningar saknas. Dessa förutsätt-ningar inkluderar bl.a. trafiksäkerhet och parkeringsmöjligheter. Villigheten att byta färdmedel tycks finnas hos bilister, eftersom de utvärderar sina vägval och andra aspekter av resan när omständigheter förändras. Att använda sig av skiftande omständigheter för att förutsäga antalet nya cyklister i Stockholm är dock problematiskt, på grund av att många av de viktigaste fak-torerna saknas i RVU Sverige.

    Resultatet blir att andelen resor som sker med cykel i Stockholm kommer att öka med en ök-ningstakt som de jämförda städerna tidigare har upplevt. Författaren har gjort en uppskattning av hur många tidigare bilister och kollektivtrafikresenärer som kan antas byta färdmedel, detta har gjorts genom att sålla bort de med sämst förutsättningar att börja cykla. Uppskattning är grundad på förutsättningarna som RVU tillhandahåller, detta medför att uppskattningen är trub-big och relativt missvisande på grund av saknade frågor i RVU Sverige.

  • 348.
    Duvalon Clark, Juan Raul
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Construction and demolition waste transport in Stockholm: A geospatial and comparative analysis between road- and intermodal transport2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 349. Dziekan, Katrin
    et al.
    Kottenhoff, Karl
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Spielen IT-Anwendungen im ÖPNV überhaupt eine Rolle für den Kunden?2005In: Internationales Verkehrswesen, ISSN 0020-9511, Vol. 57, no 12, p. 566-567Article in journal (Refereed)
  • 350.
    Edvardsson, Karin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Gustafsson, Alf
    Svevia.
    Magnusson, Rolf
    Dalarna Högskolan.
    Dust suppressants efficiency study: in situ measurements of dust generation on gravel roads2012In: The international journal of pavement engineering, ISSN 1029-8436, E-ISSN 1477-268X, Vol. 13, no 1, p. 11-31Article in journal (Refereed)
    Abstract [en]

    Dust suppressants were applied on fifteen 1km long test sections at four sites in Sweden during three summer seasons with the objective to compare their relative efficiency and determine minimum application rates in Nordic climate. Dust generation from the test sections was measured both visually and by PM10 measurements. All products except lignosulphonate, sugar and bitumen emulsion showed acceptable efficiency. Chloride solutions were the most efficient. Results indicate the possibility to reduce application rates of chlorides by applying them as solutions instead of solids. The minimum application rate for a chloride solution was estimated at 0.8m 3/km, which is equivalent to a rate reduction of 50% by weight compared with traditionally applied rates of solid chloride. The results are expected to reduce life cycle costs for gravel roads and contribute to environmental gains by reducing the release of dust into the atmosphere and chemicals into the environment.

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