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  • 1701. Zeng, H
    et al.
    Isacsson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Low Temperature Cracking of Bituminous Courses - State of the Art1995Report (Other academic)
  • 1702. Zeng, H
    et al.
    Isacsson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Low Temperature Cracking of Bituminous Courses - State of the Art1995Report (Other academic)
  • 1703. Zhang, Chao
    et al.
    Osorio, Carolina
    Flötteröd, Gunnar
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Efficient calibration techniques for large-scale traffic simulators2017In: Transportation Research Part B: Methodological, ISSN 0191-2615, E-ISSN 1879-2367, Vol. 97, p. 214-239Article in journal (Refereed)
    Abstract [en]

    Road transportation simulators are increasingly used by transportation stakeholders around the world for the analysis of intricate transportation systems. Model calibration is a crucial prerequisite for transportation simulators to reliably reproduce and predict traffic conditions. This paper considers the calibration of transportation simulators. The methodology is suitable for a broad family of simulators. Its use is illustrated with stochastic and computationally costly simulators. The calibration problem is formulated as a simulation based optimization (SO) problem. We propose a metamodel approach. The analytical meta model combines information from the simulator with information from an analytical differentiable and tractable network model that relates the calibration parameters to the simulation-based objective function. The proposed algorithm is validated by considering synthetic experiments on a toy network. It is then used to address a calibration problem with real data for a large-scale network: the Berlin metropolitan network with over 24300 links and 11300 nodes. The performance of the proposed approach is compared to a traditional benchmark method. The proposed approach significantly improves the computational efficiency of the calibration algorithm with an average reduction in simulation runtime until convergence of more than 80%. The results illustrate the scalability of the approach and its suitability for the calibration of large-scale computationally inefficient network simulators. (C) 2016 Elsevier Ltd. All rights reserved.

  • 1704.
    Zhang, Chen
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis.
    An empirical evaluation of an on-street parking pricing scheme: A case study in Stockholm inner city2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The congestion of on-street parking places in the core of metropolitan areas has attracted

    considerable attention in recent years. Low fares may result with an over consumption of

    this public good and result with a wide range of negative impacts such as the reduction of

    accessibility, deteriorating of the local air quality, extra vehicle miles travelled and increased

    traffic jams. Parking pricing is hence an important and common urban planning problem.

    However, a methodology framework for evaluating the impacts of on-street parking pricing

    is still lacking. The impact of pricing needs to be explored systematically and empirically.

    The principle aim of this thesis is to develop a systematic approach for evaluating the

    impacts of on-street parking pricing and attain concrete knowledge from the application of

    the proposed method for a case study. The project will utilize ticketing machine data and

    combine it with car floating and parking supply data. The method used in this work has the

    potential to be applied to various urban areas that utilize a similar ticketing machine system.

    The outputs of the case study function for supporting future design of on-street parking

    pricing in Stockholm. Results show that the on-street parking demand is relatively inelastic

    as a response to pricing change. The estimated own-price elasticity ranges from -0,17 to -

    0,29; and the cross price-elasticity is estimated to range from 0,13 to 0,20, for different

    street types and time-of-day periods. Raising the price leads to a significant reduction in the

    average parking duration, which contributes to a parking congestion relief. Moreover, the

    results indicate that the pricing policy affects trip scheduling and yield a more balanced

    utilization of the available parking supply through the day.

  • 1705.
    Zhang, Chen
    et al.
    KTH.
    Hanchi, Hamza
    KTH.
    Meijer, Sebastiaan
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Evaluating the Effect of Centralized Administration on Health Care Performances Using Discrete-Event Simulation2017In: 2017 PORTLAND INTERNATIONAL CONFERENCE ON MANAGEMENT OF ENGINEERING AND TECHNOLOGY (PICMET) / [ed] Kocaoglu, DF Anderson, TR Daim, TU Kozanoglu, DC Niwa, K Perman, G Steenhuis, HJ, IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    Patient flow management is increasingly motivated by the request to improve system performance. The improvements on local departments are expected with minimal negative effects on the upstream and downstream departments which are integral parts of the care pathway. Although it is widely debated that hospital buildings are expensively constructed and operated, we observe a lack of efforts on the logistical efficiency of care provision within facilities in hospitals, especially in developing areas. This askes for more research attentions towards the knowledge gap between health care supply and demand. Our work presented a simulation-based approach to study the impact of centralized administrative works by evaluating waiting times of services and resource utilizations. A discrete-event simulation (DES) model was constructed in reference to a hospital complex in Jiangsu, China. The results showed that the centralized administration benefited patients regarding a reduced total length of stay and waiting times of administration; however, reorganizing administration also influenced waiting times of medical services and resource utilizations of different types of facilities. Neglecting administration in care pathway might yield to unclear knowledge of their impacts. This article can also support the inclusion of simulation in the strategic planning phase of health care projects.

  • 1706. Zhang, W
    et al.
    Bergholm, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Multiscale blur estimation and edge type classification for scene analysis1997In: Int. J. of Computer Vision, Vol. 24, no 3Article in journal (Refereed)
  • 1707.
    Zhang, Wei
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Jenelius, Erik
    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.
    Freight transport platoon coordination and departure time scheduling under travel time uncertainty2017In: Transportation Research Part E: Logistics and Transportation Review, ISSN 1366-5545, E-ISSN 1878-5794, Vol. 98, p. 1-23Article in journal (Refereed)
    Abstract [en]

    The paper formulates and analyzes a freight transport platoon coordination and departure time scheduling problem under travel time uncertainty. The expected cost minimization framework accounts for travel time cost, schedule miss penalties and fuel cost. It is shown that platooning is beneficial only when scheduled arrival times differ less than a certain threshold. Travel time uncertainty typically reduces the threshold schedule difference for platooning to be beneficial. Platooning in networks is less beneficial on converging routes than diverging routes, due to delay at the merging point. The model provides valuable insights regarding platooning benefits for freight transport planning.

  • 1708.
    Zhang, Wei
    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.
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Planning of heavy-duty vehicle platoon formulation: basic scheduling problem considering travel time variance2016Conference paper (Refereed)
  • 1709.
    Zhang, Wei
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Sundberg, Marcus
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Karlström, Anders
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Platoon coordination with time windows: An operational perspective2017In: 20th EURO Working Group on Transportation Meeting, EWGT 2017, 4-6 September 2017, Budapest, Hungary, Elsevier, 2017, Vol. 27, p. 357-364Conference paper (Refereed)
    Abstract [en]

    It has been reported that platooning has the potential of saving fuel and increasing traffic throughput. We formulate a platoon coordination problem with soft time windows as a mixed-integer linear programming problem and solve it with exact solutions. The objective function consists of operation costs, schedule miss penalties and fuel costs. In the numerical example, a Swedish highway network model is used and the computation result shows that, for 21 vehicles, the total cost can be reduced by 3.5% when the optimal preferred arrival times are chosen. A random disturbance is then added to the optimal time windows and the optimal result shows great sensitivity with respect to the disturbance. When the mean of the disturbance becomes larger than 10 minutes, more than half of the platooning benefits will be lost. The study also analyzes the change of different cost compositions as disturbance increases.

  • 1710.
    Zhang, Wen
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, System analysis and economics.
    Mental map: A reliable definition of choice or a distorted recognition of space?2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Mental map is considered as an individual’s mental representation of his/her spatial

    cognition. People learn from the environment and add information to their personal

    mental map. It becomes important when we try to understand the relationships

    between one’s travel decision processes and their choice sets. The aim of this paper

    is to study the relationship between individuals’ activity travel patterns and their

    mental map by exploring people’s spatial cognition, their activity space and related

    factors. Two-week travel diary and mental maps were collected for the same 57

    individuals in Stockholm. Respondents were asked to report their recent trip

    information in the travel diary and draw their familiar areas in specified maps. The

    specified maps, to some extent, reflect respondents’ mental maps by transferring this

    abstract concept from one’s mind to a visual representation. The derived mental maps

    were manually drawn and transferred from graph to ASCII code in ArcGIS. The visited

    activity locations on where people travelled during the observed period were used to

    construct one’s activity space. The key determinants that construct these activity

    space and mental map will be investigated. Marginal effect of each key variable will be

    calculated to understand the magnitude of influence of each variable into the spatial

    distribution of the given individual’s activity space and mental map.

    The result shows that individual’s activity space is not necessarily within individual

    mental map. Both activity space and mental map are correlated with individual’s

    travel pattern factors. Mental map has positive influence to the formation of activity

    space. The inference of marginal effect is useful for urban planning, promoting

    transport policies and analyzing the effect of transport infrastructure since it can help

    to locate the places that constitute individual’s activity space and mental map areas.

  • 1711.
    Zhang, Yizhou
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Jenelius, Erik
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Kottenhoff, Karl
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Impact of real-time crowding information: A Stockholm metro case study2017In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 9, no 3, p. 483-499Article in journal (Refereed)
    Abstract [en]

    The paper evaluates the impact of real-time crowding information (RTCI) provision based on a pilot study at a Stockholm metro station. During a 6-day test period, RTCI for each car in the next arriving train was provided through a visual display and speakers. The impact is evaluated in three dimensions: (1) passenger attention is analyzed using video analysis; (2) passenger valuation is evaluated with traveler surveys; (3) passenger action is analyzed with in-vehicle passenger load data. It is estimated that around 25% of the passengers noticed, understood and considered the provided information useful for their travel decisions. Further, RTCI had a statistically significant positive impact on the boarding distribution between cars and, as a result, on the downstream in-vehicle crowding in the trains. RTCI reduced the share of passengers boarding the first, most crowded car by 4.3% points for trains that were crowded on arrival, and increased the share of passengers boarding the second, less crowded car by 4.1% points. The findings also suggest that many passengers may value the provided crowding information positively even though it does not change their travel decisions. The results indicate that RTCI may be a useful technology for public transport operators and agencies for increasing the utilization of available train capacity and reducing crowding.

  • 1712.
    Zhang, Yujin
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Konstruktion av framtidsrobusta trafikupplägg2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The timetable planning process in Sweden today can be considered as an annual process. The process

    dictates that operators who wish to claim capacity on the national rail network should apply for it in

    April the year prior; capacity claim in this case means both operating railway traffic and also

    possession. The current timetable planning process implies that the operators’ general production

    planning process is also annual one because the infrastructure manager (Trafikverket in Sweden) only

    has to inform the operators about definite infrastructural changes one year at a time. The consequence

    of this is that an operator could not be certain of the definite conditions more than a year at a time

    and it is fully possible that a certain route may receive a supplement two years in time that will cause

    an established traffic system to collapse and thus needing to revise the production plan for that year.

    The aim of this degree project is to examine whether it is possible to generate a model or process chart

    to enable production planning several years ahead in time. The model should be able to take

    infrastructural changes into account and therefore guaranteeing the sustainability of a certain traffic

    system over a number of years. The degree project will use the Mälarbanan project as a case study.

    The method applied for the degree project is to first introduce the topic of timetable planning (chapter

    2). Because the timetable planning process is harmonized within greater parts of EU and follows certain

    standards, the processes in Switzerland and the Netherlands will also be described in chapter 2 and

    finally compared to the process in Sweden enlightening the differences. After having described the

    general process, the report will shift focus to focusing on how to construct such a model that fulfills

    the aim of the project (chapter 3). Much of the material and arguments made in chapter 3 are directly

    gathered from the author’s own professional experience as a traffic planner at SJ AB meaning that

    certain terms used in the chapter will also be SJ-specific. The author believes however that the process

    chart itself is applicable to any railway operator within the frames of Trafikverket’s timetable planning

    process. Chapter 4 of the report is dedicated to the Mälarbanan case study where the focus is set on

    describing the infrastructural conditions and how the model created in chapter 3 should be applied to

    Mälarbanan.

    The main result of the degree project is a process chart describing how a railway operator should plan

    its production several years in time given the infrastructural conditions today. The main result from

    the Mälarbanan case study is the assessment of two different traffic scenarios proposed at the

    moment. Because the Mälarbanan case study is still an ongoing investigation within SJ AB no definite conclusions and recommendations could be made at the time of this degree project’s submission.

  • 1713.
    Zhang, Yujin
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Linjenätsutredning i Täby kommun.2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The public transport network in Täby commune consists currently of two types of bus line of which

    both belong to the category of feeder lines. The first type terminates at Danderyds sjukhus and feeds

    to the subway whereas the second type terminates at Täby centrum and feeds to Roslagsbanan, a

    suburban narrow-gauge railway system in northern Stockholm. The trunk bus line that connects

    greater parts of the commune with Danderyd is the ring line 604 and goes both clockwise (604H) and

    counterclockwise (604V). The main negative aspect of this structure is the complicity in incorporating

    it timetable-wise with other bus lines that share the same route, such as through Enebyberg.

    The goal of this project is to investigate the possibilities of splitting ring line 604 and connecting the

    ends to two different bus routes that terminate at Täby centrum today. Apart from easing the

    coordination with other bus lines through Enebyberg, the extension also creates new direct

    connections from various areas in Täby to Danderyds sjukhus. The time perspective of this project is

    winter 2013, which means it is taken for granted that the overall demand and volumes of passengers

    will remain the same as today.

    The method applied will be creating a zero option and a series of different scenarios. The different

    scenarios will be compared regarding the total trip time, travel distance and transfer times. From the

    comparisons one of the scenarios will be chosen and schedules for the proposed network will be

    constructed. After constructing the timetables for the proposed network, line block calculation will

    be made to determine the amount of vehicles needed for the scenario. The aim of the latter part is

    to determine whether the chosen scenario will lead to a decrease in cost for the entrepreneur in

    terms of vehicle usage. Evaluation of the scenarios will be done with the help of VISUM, a modeling

    program at macro scale. The base network is from SLL Trafikförvaltningen from year 2010 with the

    associated OD-matrices. Construction of the timetables and line blocks will be done in Excel.

    Results from the scenario evaluations show that an extension of bus lines 612 and 615 to Danderyds

    sjukhus will improve all of the indicators used in this project. From the timetable and line block

    constructions it is shown that the proposal does not lead to an increase in vehicle usage. The biggest

    drawback of the proposal is the coordination between 611 and 612 through Enebyberg and

    Roslagsbanan

    ’s timetable. Given the current conditions, it is hard to coordinate 611 and 612 through

    Enebyberg and at the same time guarantee connections with Roslagsbanan at Hägernäs with the

    timetable offered today. Another downside is bus line 615, which has more line types than the

    optimum. The suggestion is to shift parts of 605’s resource to 615 in order to create

    rigid 30-minute

    traffic between Danderyds sjukhus and Arninge during bigger parts of the day.

    The overall result of the project is positive, but not all goals were met. The main reason for not

    meeting all the goals is because that the information required to draw the necessary conclusions are

    of the sensitive type that a company should and would keep secret. The general result of the project

    is nonetheless regarded as acceptable and definitely aids further investigations within the topic.

  • 1714. Zhang, Z
    et al.
    Roque, R
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Evaluation of Laboratory Measured Crack Growth Rate for Asphalt Mixtures2001In: Transportation Research Record, Vol. 1767Article in journal (Refereed)
  • 1715. Zhang, Z
    et al.
    Roque, R
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Sangpetgnam, S
    Identification and Verification of a Suitable Crack Growth Law for Asphalt Mixtures2001In: Journal of Asphalt Paving Technologists, Vol. 70Article in journal (Refereed)
  • 1716. Zhao, Yong
    et al.
    Kockelman, Kara
    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.
    Welfare calculations in discrete choice settings: an exploratory analysis of error term correlation with finite populations2012In: Transport Policy, ISSN 0967-070X, E-ISSN 1879-310X, Vol. 19, no 1, p. 76-84Article in journal (Refereed)
    Abstract [en]

    A difference in logsum terms (also known as inclusive values) is becoming a standard practice for anticipating the welfare impacts of transport policy when choice alternatives are discrete and behavior is (assumed to be) random-utility maximizing. However, this calculation is only an approximation when the population under study is finite. This paper examines the effect of error term correlations in such welfare analyses with finite samples, recognizing that individual preferences and unobserved attributes influencing choice are unlikely to change much, if at all, across scenarios or across alternatives. Such measures appear reasonably robust to deviations in assumptions of correlation. Nevertheless, we identify cases when the synthetic population samples need to be quite large for the average logsum to be realized. Another finding in these results is the substantial variation that emerges across synthetic populations, suggesting that policies that appear welfare-improving (when evaluated with average welfare formulations) may well be welfare-reducing (or vice versa) for a wide variety of actual, finite populations.

  • 1717.
    Zhao, Yu
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis.
    Identification and classification of activity centers based on passenger flows data.2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the past decades, the spatial structure of metropolitan areas has progressively changed

    towards a more polycentric structure. Many researchers have studied this polycentric structure

    in the context of North American and European metropolitans by identifying sub-centers,

    mainly using two methods which are analyzing the employment or population density or

    mobility data. In spite of huge effort in identifying sub-centers, fewer studies characterize the

    identified sub-centers and classify them based on their patterns and features simultaneously.

    And this research will identify sub-centers and then classify them as well.

    Following the introduction of polycentricity and a review of previous methodologies for

    identification and classification of sub-centers, this study introduces two different algorithms:

    flow-based and distance-based for identifying sub-centers based on passenger flows data at

    public transport stations. In addition, the study presents the classification process of identified

    clusters based on time-dependent passenger flows data. Temporal profiles of each cluster are

    created and used to describe their characteristics, and then classification is conducted based on

    hierarchical clustering analysis.

    As a case study, the emergence of polycentric structure in Stockholm County is analyzed using

    public transport passenger flows at each station including metros, commuter trains, buses and

    light rails. After comparing results of the two proposed algorithms, the distance-based is chosen

    for Stockholm case. The identification algorithm yields 17 clusters. These 17 clusters are then

    classified using three different indicators based on flow data by time intervals. As a result, we

    have three classification results. Finally, the classification results are analyzed and synthesized

    by considering the urban environment of clusters and their roles in transport network,

    providing a comprehensive interpretation of resulted clusters. Clusters are classified into seven

    more general classes of center, business, residential, hub or combinations of them. The result

    suggests that each cluster is associated with distinctive functions and they are all active, unlike

    ‘’sleeping towns’’, however, clusters in the inner city are still able to generate and attract more

    flows and flows are still more concentrated in the central part, indicating the aim to release

    pressure from central part by polycentric structure hasn’t been fully achieved yet.

  • 1718.
    Zhu, Jiqing
    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.
    Kringos, Niki
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Polymer modification of bitumen: Advances and challenges2014In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 54, no 1, p. 18-38Article, review/survey (Refereed)
    Abstract [en]

    Advances and challenges in the field of bitumen polymer modification for road construction during the last 40 years are reviewed in this paper. The history of bitumen polymer modification is described chronologically. Some popular plastomers and thermoplastic elastomers in bitumen modification are discussed regarding their advantages and disadvantages, including polyethylene (PE), polypropylene (PP), ethylene-vinyl acetate (EVA), ethylene-butyl acrylate (EBA), styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS) and styrene-ethylene/butylene-styrene (SEBS). Although these polymers all improve bitumen properties to some extent, there are still some drawbacks limiting the future development of bitumen polymer modification, such as high cost, low ageing resistance and poor storage stability of polymer modified bitumen (PMB). Researchers attempted various ways to remove these drawbacks. Some technical developments for removing drawbacks are reviewed in this paper, including saturation, sulfur vulcanization, adding antioxidants, using hydrophobic clay minerals, functionalization and application of reactive polymers. The future development of polymers for bitumen modification is analyzed as well. Since it is currently challenging to perfectly achieve all expected PMB properties at the same time, some compromised recommendations are given in this paper, among which greatly enhancing the properties with an acceptably high cost, significantly reducing the cost with relatively poor properties and their combinations. Functionalization is emphasized as a promising way to enhance the properties of currently used polymers and develop new-type polymer modifiers with much greater success in the future. It is also recommended that future research on bitumen polymer modification focuses more on function development towards enhancing: adhesion with aggregates, long-term performance and recyclability.

  • 1719.
    Zimmermann, Maëlle
    et al.
    Department of Computer Science and Operations Research, Universit\'e de Montr\'eal, QC, Canada.
    Blom Västberg, Oskar
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, System Analysis and Economics. Royal Institute of Technology.
    Frejinger, Emma
    Department of Computer Science and Operations Research, Universit\'e de Montr\'eal, QC, Canada.
    Karlström, Anders
    Capturing correlation with a mixed recursive logit model for activity-travel schedulingManuscript (preprint) (Other academic)
    Abstract [en]

    Representing activity-travel scheduling decisions as path choices in a time-space network is an emerging approach in the literature. In this paper, we model choices of activity, location, timing and transport mode using such an approach and seek to estimate utility parameters. Relaxing the independence from irrelevant alternatives (IIA) assumption of the logit model in this setting raises a number of challenges. First, overlap in the network may not fully characterize the correlation between paths, due to their interpretation as activity schedules. Second, the large number of states that are needed to represent all possible locations, times and activity combinations imposes major computational challenges to estimate the model. We combine recent methodological developments to extend previous work that allow to model complex and realistic correlation patterns in this type of network. The resulting model is a mixed recursive logit which keeps the advantages of the recursive logit for prediction. We use sampled choices sets in order to estimate the model in reasonable time for large-scale, dense time-space networks. In addition to estimation results, we present an extensive empirical analysis which highlights the different substitution patterns when the IIA property is relaxed, and a cross-validation study which confirms improved out-of-sample fit.

  • 1720.
    Zomer, Lara-Britt
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Daamen, Winnie
    TU Delft.
    Meijer, Sebastiaan
    KTH, School of Technology and Health (STH), Health Systems Engineering, Health Care Logistics.
    Hoogendoorn, Serge
    TU Delft.
    Managing Crowds: The Possibilities and Limitations of Crowd Information During Urban Mass Events2015Conference paper (Refereed)
    Abstract [en]

    Thischapter,basedonamixedmethodresearchapproach,offersinsights into possibilities and limitations of using ICT measures for crowd management and distribution during urban mass events (UMEs). Based on literature, practical applications and analyses of research results, we propose crowd management should consider characteristics of both crowds and UMEs to increase information effectiveness. In relation to urban planning, results show that possibilities to influence a crowd’s behavior depend on available (and known) choice sets offered in various locations, while distances towards locations across city centers appear less important. Limitations appear to be related to scarce knowledge on what drives crowd members to adapt or adhere to their activity choice behavior. Such insights are essential for smart cities striving for an optimal use of infrastructural capacity, as both the ambiguous effects of ICT measures, as well as a crowd’s self-organizing capacity should be taken into account for delaying, solving and preventing dis- ruptions of pedestrian flows in city centers. 

  • 1721.
    Ágústsson, Arnar
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Fish oil in Icelandic road constructions.: A case study of bituminous binder mixtures modified with bio-oil.2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis an extensive background study on the use of bio-oil modified

    binder, used in surface dressings in Iceland, was carried out. Surface dressings,

    or chip seals, are paved by first spraying out binder and then distributing

    aggregates over the surface before compaction. The bio-oil, most notably fish

    oil ethyl ester or rape seed oil, is included in a binder mixture to lower its

    viscosity, enabling the binder to be sprayed out at a lower temperature than

    unmodified bitumen.

    In January 2013, severe bleeding of binder was noticed on road sections

    paved with bio-oil modified surface dressings in the northern part of Iceland.

    Following the bleeding, the Icelandic Road and Coastal Administration

    (IRCA) sent samples of the sections in question, as well as binder samples, for

    testing at the laboratory of Highway and Railway Engineering at KTH Royal

    Institute of Technology (KTH) in Stockholm, Sweden. The conclusions of that

    study were that the fish oil ethyl ester was highly polar and had solubility issues

    with the bitumen. This was found to have led to the fish oil separating

    from the binder mixture and covering the stones, preventing bonding between

    aggregates and binder [1].

    The laboratory tests in this thesis extend on the aforementioned research.

    Through the background investigation it was found thatWetfix N, an adhesion

    promoter, was used in the binder mixture to facilitate bonding to the aggregates.

    Based on these findings, previous work and field experience in Iceland,

    two sample sets were created. The first sample set included 7.5% of either fish

    oil ethyl ester or rape seed oil by weight, while the second set included 4% of

    the same bio-oils by weight. To determine the effect of the adhesion promoter,

    all samples were tested with and without Wetfix N. Furthermore, all samples

    were put through a short-term aging treatment to simulate the process during

    mixing and paving, and tested again.

    The findings of this study suggest that the fish oil ethyl ester is more suitable

    for road constructions, compared to the rape seed oil, and that adhesion

    promoter should always be included when paving surface dressings in Iceland.

    Furthermore, the samples tested cannot be recommended for field use due to

    high polarity in the sample with a fish oil concentration of 7.5% and too high

    viscosity in the sample which includes 4% of fish oil. Therefore, it can be said

    that the upper and lower limits have been narrowed to the range between the

    two concentrations tested. To better understand the properties and behavior

    of the sample mixtures, a complete adhesion test with aggregates is advisable.

    Viscosity testing of samples which include between 4.5% and 7% of fish oil

    by weight are recommended and the mixture with the lowest concentration

    that passes IRCA’s guidelines for spraying viscosity at a desired temperature

    should be used in practice.

  • 1722.
    Ängskog, Per
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap.
    Oakes, Ben
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Maintaining Functional Safety under an Intentional Electromagnetic Interference (IEMI) Attack2013Conference paper (Refereed)
    Abstract [en]

    The importance of protection against IEMI effects in civilian applications is growing rapidly as more and more societal infrastructure is equipped with electronic devices. This paper discusses methods to help maintaining functional safety in the event of an IEMI attack.

  • 1723.
    Ólafsdóttír, Ásdís
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Bus service performance analysis.: Case study: Bus line 1 in Stockholm, Sweden2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Transit reliability is one of the key factors in running a successful transit system from both

    passengers’ and operators’ perspective. To improve the reliability of a transit service a

    performance analysis is necessary. There are several service measures that can be applied to

    evaluate the performance of a transit service, both in relation to service punctuality and

    service regularity. Punctuality can be considered of higher importance on low frequency

    lines and regularity on high frequency lines. Bunching is used to describe how vehicles

    occupying the same bus route tend to bunch up and consequently the reliability decreases.

    For improving reliability several holding control strategies can be applied such as schedulebased

    holding, where early vehicles are held at time points, and headway

    ‐based holding,

    where vehicles are held to retrieve even headways between consecutive vehicles.

    This thesis provides an overview of several different performance measures that can

    be analyzed using

    Automatic Vehicle Location data (AVL) and Automatic Passenger Counters

    data (APC) collected from bus vehicles. As a case study, bus line 1 in Stockholm was

    analyzed. The line is a high frequency, inner city bus line, where schedule based holding is

    the current holding control strategy.

    The performance analysis included an analysis of service regularity, service

    punctuality, dwell times, passenger boarding/alighting and load, and run times. A linear

    regression analysis was applied to evaluate the effects of passenger activity on the dwell

    times.

    The results showed that the overall service performance decreased along the line for

    both directions. Vehicle trajectories revealed increased bunching along the line. The drivers’

    compliance to holding analysis showed that there was room for improvement. Overall, the

    analysis showed that the current holding control strategy does not retrieve headway

    regularity and that the schedule for vehicle run times was too tight and needs revision.

    Furthermore, switching to headway

    ‐based holding was suggested.

  • 1724.
    Östlund, Stefan
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Andersson, Evert
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Kottenhoff, Karl
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Efficient Passenger Trains for the Future1999In: Proceedings of the WCRR99, 1999Conference paper (Refereed)
32333435 1701 - 1724 of 1724
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