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  • 101.
    Flötteröd, Gunnar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport planning, economics and engineering.
    Lämmel, Gregor
    Bidirectional pedestrian fundamental diagram2015In: Transportation Research Part B: Methodological, ISSN 0191-2615, E-ISSN 1879-2367, Vol. 71, p. 194-212Article in journal (Refereed)
    Abstract [en]

    This article presents a new model of stationary bidirectional pedestrian flow. Starting out from microscopic first principles, a bidirectional fundamental diagram (FD) is derived that defines direction-specific flow rates as functions of direction-specific densities. The FD yields non-negative and bounded flows and guarantees that the instantaneous density changes that would result from these flows stay bounded between zero and jam density. In its minimal configuration, it uses just as many parameters as a unidirectional triangular FD: maximum walking speed, jam density, a collision avoidance parameter (from which the backward wave speed can be derived). A one-on-one mapping between the parameters guiding uni- and bidirectional pedestrian flows is proposed and both conceptually and empirically justified. Generalizations of the FD that maintain its desirable properties turn out to be straightforward by making its parameters density-dependent. The FD performs very well in comparisons against simulated and real data.

  • 102. Flügel, Stefan
    et al.
    Flötteröd, Gunnar
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport planning, economics and engineering.
    Kwong, C.K.
    Steinsland, C.
    Evaluation of methods for calculating traffic assignment and travel times in congested urban areas with strategic transport models2014Report (Other (popular science, discussion, etc.))
  • 103.
    Fosgerau, Mogens
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Lindberg, Per Olov
    KTH, School of Architecture and the Built Environment (ABE), Transport Science. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Mattsson, Lars-Göran
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Weibull, Jörgen
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.).
    Invariance of the distribution of the maximumManuscript (preprint) (Other academic)
    Abstract [en]

    Many models in economics involve probabilistic choices where each decision-maker selects the best alternative from a finite set. Viewing the value of each alternative as a random variable, the analyst is then interested in the choice probabilities, that is, the probability for an alternative to give the maximum value. Much analytical power can be gained, both for positive and normative analysis, if the maximum value is statistically independent of which alternative obtains the highest value. This note synthesizes and generalizes previous results on this invariance property. We provide characterizations of this property within a wide class of distributions that comprises the McFadden GEV class, show implications in several directions, and establish connections with copulas. We illustrate the usefulness of the invariance property by way of a few examples.

  • 104.
    Fröidh, Oskar
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport planning, economics and engineering.
    Design speed for new high-speed lines2014In: Journal of Rail Transport Planning and Management, ISSN 2210-9706, Vol. 4, no 3, p. 59-69Article in journal (Refereed)
    Abstract [en]

    There are examples where the design speed of new high-speed lines has been based more on performance of present technology than on optimisation of the cost-benefit outcome considering future needs. A model for optimising the design speed, or intended dimensional speed, for new high-speed lines to attain more cost-efficient planning is presented in this paper. This model, HSLdim, includes a travel demand sub-model where the dependent variable is commercial speed, and design speed dependent infrastructure cost and train operating cost sub-models, adapted for fast optimisation. Some aspects of a proposed high-speed network in Sweden have been analysed. The average speed should be as high as possible to maximise benefits. The optimal design speed for the Swedish case was found to be 325-350. km/h depending on the share of ballastless track, which has a significant influence on the construction costs. This is in line with international experience but somewhat higher than the planned design speed of 320. km/h. To summarise, the paper gives an example that analysis could increase the socio-economic output by optimising the design speed in a CBA to take future needs into consideration in new high-speed rail projects.

  • 105.
    Fröidh, Oskar
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Järnvägens utvecklingspotential och konsekvenser för berörda kommuner2016Conference paper (Other (popular science, discussion, etc.))
    Abstract [sv]

    Utvecklingslinjer i godstrafiken:

    • Avreglering och borttagande av organisatoriska hinder inom Europa• Effektivisering av basindustrins transporter och utveckling av nya produkter för högvärdigt gods• Utveckling av kombinerade transporter järnväg – lastbil och järnväg – sjöfart• Anpassning av priserna på transporter till verklig kostnad för miljö, olyckor och trängsel (internalisering av externa effekter)

    Punktlighet och kapacitet för godstrafik på järnväg viktigt

    Utveckla morgondagens persontrafik:

    Utbudsfaktorer (annonseras i tidtabellen)

    •Kortare restider•Flera direktförbindelser•Högre turtäthet•Lägre biljettpriser

    Kvalitetsfaktorer (viktiga ospecificerade förutsättningar)

    •Punktlighet och regularitet•Trygghet och säkerhet•Renhållning, städning•Service och användarvänlighet (enkelhet)

    Kan förarlös tågdrift bidra till mer attraktiv tågtrafik?

  • 106.
    Fröidh, Oskar
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Kapacitet i nätverk – möjligheter med NEMO2016Conference paper (Other academic)
    Abstract [sv]

    Etapp 1, implementering

    Utveckla metod för att analysera bankapacitet i nätverk som strategiskt planeringsverktyg

    •Förbättrad transportkvalitet•Kostnadseffektiva produktionsupplägg i godstrafiken

    → Möjliggör ökning av godstransporterna på järnväg

    Möjliga analyser:

    •Optimering vid omstrukturering av vagnslasttrafiken •Bättre kapacitetsutnyttjande i järnvägsnätet som helhet •Effekter av differentierade och styrande banavgifter (kapacitetsdelen) •Järnvägsnätets standard (tillåten tåglängd, axellast och lastprofil) •Sårbarhetsaspekter (trafikavbrott) •Miljöeffekt av varje alternativ beträffande emissioner för tågtrafiken •Underlag för strategiska infrastrukturinvesteringar.

  • 107.
    Fröidh, Oskar
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Perifera stationer: resenärernas värderingar av stationslokaliseringen2017In: / [ed] VTI, 2017Conference paper (Other academic)
    Abstract [sv]

    Projektets syfte:

    •Att förstå och komplettera de kända effektsambanden av lokalisering av nya järnvägsstationer med kunskap som bidrar till mer långsiktigt hållbar samhällsutveckling.

    •Att finna stöd för åtgärder som bryggar över gapet mellan planeringen i praktiken och bästa kunskap (”genomförandeunderskottet”).

    •Att ge underlag för fortsatt planering av nya stationer för regionalt och interregionalt tågresande, särskilt med tanke på nya stambanor.

    Några preliminära slutsater:

    •Längre anslutningsresor till perifera än till urbana stationer (median 3 km längre, medel 4 km längre)

    •Färdmedelsval skiljer vid anslutningsresor till urbana jmf perifera stationer (speciellt till fots/med bil)

    •Trygghet viktigt för de flesta resenärer, enskilda stationer avviker men ingen skillnad mellan urbana och perifera

    •Hög värdering av god turtäthet i anslutande lokaltrafik och bemannade stationer (men relativt dyra åtgärder)

  • 108.
    Fröidh, Oskar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Adolphson, Marcus
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment.
    Jonsson, Daniel
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, System Analysis and Economics.
    Andersson, Josef
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport Planning, Economics and Engineering.
    Lokalisering av järnvägsstationer – effekter för samhällsplanering, resande och tillgänglighet2018Report (Other academic)
    Abstract [sv]

    14 ny- eller ombyggda stationer för i första hand fjärrtrafik och långväga regionaltrafik med sedan 1990 kraftigt förbättrat tågutbud har valts ut i studien: Från söder till norr Malmö Hyllie, Triangeln och Malmö C, Laholm, Flemingsberg, Södertälje syd, Läggesta, Strängnäs, Eskilstuna C, Bålsta, Uppsala C, Söderhamn, Umeå Ö och Umeå C. Analysen omfattar tre huvuddelar: Dels 1) en analys av avresande tågresenärers resvanor och värderingar, dels 2) en morfologisk studie över samhällsstrukturens förändringar 1993–2013 och kommunernas översiktsplaner, och för stationerna i Mälardalen dels 3) en modellanalys av förändringar i trafik och tillgänglighet vid alternativ lokalisering.

    Sammanfattningsvis tyder studien på att valet av lokalisering av nya stationer får effekter för samhället när det gäller samhällsstruktur, resenärernas nöjdhet, resvanor och färdmedelsval och tillgänglighet till arbetsplatser och service, vilket påverkar järnvägssystemets attraktivitet och därmed reseefterfrågan. Centralt eller urbant lokaliserade stationer framstår därmed som mer attraktiva och bättre ur systemsynpunkt än perifert lokaliserade stationer.

    Anledningen till att perifera stationer tillkommer är dock att man vill minska anläggningskostnaderna eller intrång i redan bebyggd miljö jämfört med en urban lokalisering. När detta blir aktuellt är det viktigt med bra anslutande kollektivtrafik och andra stödjande strategier för bland annat exploatering. Föreliggande studie tillför dock argument att värdera de positiva effekterna av en urbant lokaliserad station högre än idag.

    Vi har identifierat möjligheter att vidareutveckla metoderna för att utvärdera effekterna av stationslokalisering inom fler områden. Det går också införa analyserna i lokaliseringsutredningar för att förbättra beslutsunderlaget i framtida val av stationslokalisering.

  • 109.
    Fröidh, Oskar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Ceccato, Vania
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    Determinants of passengers’ perceived security at railway stations2017Conference paper (Other academic)
    Abstract [en]

    A survey has been performed on departing middle- and long-distance train passengers on a selection of 14 since 1990 new or rebuilt railway stations in Sweden. The passengers’ rating of security was one of the questions included in the survey, which dealt with several aspects on localization of the station. A linear regression analysis (OLS) revealed that the Perceived Station Security (PSS) Index is explained by a number of physical factors in the station environment. Individual or socio-economic factors are however too vague to be significant. The model is significant but the model fit is low and the results should be interpreted as preliminary. Examples of environmental factors that increase the PSS are if the station has built-in stairs between station building and platforms and if there is a café or restaurant with seating in the station, while reconstruction in progress decreases the PSS. The distance to the city or local centre has an effect, and peripheral stations in general have a lower PSS than centrally located.

  • 110.
    Fröidh, Oskar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Sipilä, Hans
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Warg, Jennifer
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Capacity for express trains on mixed traffic lines2014In: International Journal of Rail Transportation, ISSN 2324-8386, Vol. 2, no 1, p. 17-27Article in journal (Refereed)
    Abstract [en]

    Mixed traffic with large speed differences between fast and slower trains consumesmore capacity and makes the system sensitive to disruptions. This article focuses onadequate train configuration for increasing the top speed for express trains like theGreen Train and how that affects capacity on lines with heterogeneous traffic.Microscopic simulation of a future timetable selected by criteria revealed by analyticaltimetable analysis for a chosen structure of services combines the advantages of twomethods and makes it possible to reveal relevant characteristics for different alternatives.Punctual short stops through better train layout and skip-stop operation forregional trains are a few of the measures that are shown to have compensating effectsfor the increase in capacity utilisation and can reduce disruptions. Although it ispossible to reduce the perturbations by means of different measures, the basic problemwith mixing fast and slower trains on the same line still remains.

  • 111.
    Fu, Jiali
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Evaluating and Improving the Transport Efficiency of Logistics Operations2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The thesis focuses on evaluating and improving the transport efficiency of two types of logistics operations in the supply chain.

    One research area is the production of raw material in construction operations, specifically earthmoving operations. Methods and tools are developed to provide decision support in improving the transport efficiency of earthmoving at the vehicle and the systems levels. Using known road topography and a GPS unit, an optimal control problem is formulated and solved (Paper III) to determine the optimal gear shift sequence and timing in order to improve the transport efficiency at the vehicle level. For decision support at the systems level, a Fleet Performance Simulation (FPS) model is designed (Paper IV) to evaluate the transport efficiency for a given mix of construction vehicles in earthmoving. The FPS system is integrated with an optimization algorithm to solve the optimal fleet composition problem for earthmoving operations (Paper V & VI). Construction operations are dynamic and the environment is changing constantly, which bring difficulties in decision-making. Using GPS data from construction vehicles, a map inference framework (Papers I & II) is developed to automatically extract relevant input to decision support at the vehicle and the systems levels, which include the locations of various workstations, driving time distributions and road networks.

    The second research area is the transport efficiency of urban distribution system, which is in the final phase of the supply chain. An off-peak delivery pilot project in Stockholm is used as the background, designed to evaluate the potential for commercial vehicles to make use of off-peak hours for goods delivery. The thesis (Paper VII) evaluates the transport efficiency impacts of the off-peak pilot. An evaluation framework is defined where transport efficiency is studied in a number of dimensions. GPS data, fleet management data, and logistic information are used to assess the impacts.

  • 112.
    Fu, Jiali
    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.
    Off-peak goods deliveries in Stockholm inner city - evaluation of transport efficiency2016Conference paper (Other (popular science, discussion, etc.))
  • 113.
    Fu, Jiali
    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.
    Transport efficiency of off-peak urban goods deliveries: A Stockholm pilot study2017Conference paper (Refereed)
  • 114.
    Fu, Jiali
    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.
    Haris, Koutsopoulos
    Driving time and path generation for heavy construction sites from GPS traces2016In: IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC, IEEE, 2016, p. 1141-1146Conference paper (Refereed)
    Abstract [en]

    The paper presents a methodology for using GPS probe data to automatically extract the driving time between workstations and build a detailed representation of the paths between workstations in a construction environment. The inferred driving time distribution is aimed as input to construction simulation models to assess fleet performance, while the path information can be utilized to examine the performance of individual vehicles. A case study, using GPS data collected from a construction site, is used to demonstrate the capability of the proposed approach. The GPS data are processed without any prior knowledge about the underlying work environment. The results show that the proposed approach is capable of accurately inferring the driving time distribution and the paths between workstations.

  • 115.
    Fu, Jiali
    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.
    Koutsopoulos, Haris
    Identification of workstations in earthwork operations from vehicle GPS data2016Conference paper (Refereed)
    Abstract [en]

    Increasing availability and the use of Global Positioning System (GPS) devices open great opportunities for various transportation applications. The authors propose a generative probabilistic model for extraction of locations of workstations in earthwork operations using raw GPS traces from construction vehicles. The probabilistic model incorporates the GPS measurements with relevant information extracted from the GPS data to compute locations of different workstations as probability distribution over the environment. The location of workstations will be used as a part of a map inference method for generating and continuously updating the layout and road network topology of the construction environment. A detailed case study was conducted with construction equipment at a complex site. The authors first demonstrate the probabilistic model to extract the locations of loading stations using vehicle speed and interactions among vehicles, and then to discover dumping stations with help of vehicle moving patterns. The results from the experiment show that the proposed method is able to discover important places and workstations for earthwork environment efficiently and in sufficient details.

  • 116.
    Fu, Jiali
    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.
    Koutsopoulos, Haris N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering. Department of Civil and Environmental Engineering, Northeastern University, 360 Huntington Avenue, Boston, USA.
    Identification of workstations in earthwork operations from vehicle GPS data2017In: Automation in Construction, ISSN 0926-5805, E-ISSN 1872-7891, Vol. 83, p. 237-246Article in journal (Refereed)
    Abstract [en]

    The paper proposes a methodology for the identification of workstations in earthwork operations based on GPS traces from construction vehicles. The model incorporates relevant information extracted from the GPS data to infer locations of different workstations as probability distributions over the environment. Monitoring of workstation locations may support map inference for generating and continuously updating the layout and road network topology of the construction environment. A case study is conducted at a complex earthwork site in Sweden. The workstation identification methodology is used to infer the locations of loading stations based on vehicle speeds and interactions between vehicles, and the locations of dumping stations based on vehicle turning patterns. The results show that the proposed method is able to identify workstations in the earthwork environment efficiently and in sufficient detail.

  • 117. Gentile, Guido
    et al.
    Cats, Oded
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering. Delft Univ Technol, Netherlands.
    Introduction to the special issue on public transport modelling2017In: EURO Journal on Transportation and Logistics, ISSN 2192-4376, E-ISSN 2192-4384, Vol. 6, no 3, p. 219-220Article in journal (Other academic)
  • 118.
    Hagman, Jens
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    Ritzén, Sofia
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    Janhager Stier, Jenny
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    Susilo, Yusak
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Total cost of ownership and its potential implications for battery electric vehicle diffusion2016In: Research in Transportation Business and Management (RTBM), ISSN 2210-5395, E-ISSN 2210-5409, Vol. 18, p. 11-17Article in journal (Refereed)
    Abstract [en]

    Battery electric vehicles (BEVs) have been slow to diffuse on the international as well as the Swedish market. Previous studies have indicated situational factors such as economic factors, size and performance to be of major importance for vehicle purchasers in their choice of vehicle. In this paper, the authors explore a consumer centric total cost of ownership (TCO) model to investigate the possible discrepancy between purchase price and the TCO between internal combustion engine vehicles (ICEVs), hybrid electric vehicles (HEVs) and BEVs. The creation and testing of the TCO model reveals that computation could be a challenging task for consumers due to bounded access of relevant data and the prediction of future conditions. The application of the model to the vehicle sample found that BEVs could be cheaper compared to ICEVs and HEVs. The findings in this paper could prove to be of importance for policy and marketing alike in designing the most appropriate business models and information campaigns based on consumer conditions in order to further promoting the diffusion of BEVs in society.

  • 119.
    Hashim, Elaff
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport planning, economics and engineering.
    Jönsson, Jonathan
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport planning, economics and engineering.
    Busshållplatsers kapacitet: Utvärdering av tillämpbarhet av modell från Highway Capacity Manual 2000 med uinderlag från busstrafik i Stockholms innerstad2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Stockholm is growing with almost two fully loaded SL-buses a day. One of the consequences that derive from this is the increase of public transport travelers who put the regionally governed public transport up to the test in terms of its capacity. The Transport administration in Stockholm County initiated 2015 a project with the purpose of simplifying the calculation of bus stop capacities. A hypothesis (set up by the Transport administration) based on that a model for calculation of bus stop capacities could be calibrated for Stockholm conditions is being researched in this bachelor’s essay.

    The study is implemented by self-collected traffic data from bus stops located in the Stockholm city center. Furthermore, the data was processed in order to gather the parameters relevant to the examined model. Parallel to the ongoing research a review of literature was carried out in order to broaden the basic knowledge of the subject.

    The studied bus stops were chosen based on what the length of the average dwell time was considered to be. The average dwell time is the parameter specified as the most critical to the model.

    The collected data was analyzed and parameter values were produced. Finally the results of the processed data were analyzed. The chapter of discussions contains thoughts about several of the included parameters and a broader questioning of the actual user potential of the model compared to different capacity-calculating methods.

    Conclusions regarding the application of the model for estimation of capacity on existing bus stops in Stockholm city center could not be drawn. The reason for this is that saturated conditions were not achieved during the performed field surveys. Further studies are necessary in order to be able to validate, and if necessary calibrate, the model. These studies should be carried out by measurements at traffic configurations with more variety in terms of capacity determining factors in road and bus stop designs, than those conducted in this study

  • 120.
    Hong, Beichuan
    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.
    Path Planning for Wheel Loaders: a Discrete Optimization Approach2017Conference paper (Refereed)
  • 121.
    Hong, Beichuan
    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.
    Quantification of Emissions for non-road Machinery in Earthwork: Modeling and Simulation Approaches2017Conference paper (Refereed)
    Abstract [en]

    Earthwork, as an essential part of almost all heavy construction projects, is an energy consuming procedure and pollution source for both transport and construction sectors. Due to the increasing need and interest to achieve sustainable development in construction, the evaluation of emission and energy impact in earthwork is of high importance for improving the environmental sustainability. This paper proposes an approach to estimate emissions and fuel usage of construction equipment by using experimental data collected from a project mainly carried out in China. In the experiment, emissions and operational parameters of two loaders and two hauler trucks were measured and analyzed. Based on the power efficiency and other factors, different operation cycles are defined for wheel loader and trucks in the real measurement. Then, through establishing an estimation approach, the emission and fuel rates for different operational cycles are finally calculated. The results show that there are remarkable differences for emissions under different working conditions. In order to evaluate and reduce the emissions and fuel values of the whole earthwork project, a discrete-event simulation (DES) is developed and employed to simulate the earthwork scenarios in a detailed case study. The model provides a basis for the integration of the emission calculation with earthwork simulation. During the evaluation, an alternative plan has been proposed and analyzed for lowering the environmental impacts of the earthmoving operations.

  • 122.
    Hong, Beichuan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering. Wuhan University of Technology, China.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Chen, Hui
    Lv, Lin
    Modeling of dynamic NOx emission for nonroad machinery: a study on wheel loader using engine test data and on-board measurement2016Conference paper (Refereed)
    Abstract [en]

    Quantification of nonroad machinery emissions is of high importance for improving heavy construction processes especially concerning environmental sustainability. In comparison to the substantial research effort on modeling dynamic emissions for road transport, there is, however, lack of knowledge on how to quantify dynamic emissions during construction operations. This paper proposes an approach to model dynamic NOx emission for nonroad construction machinery using recent experimental data collected by a wheel loader operated in the Chinese environment. In the experiment, emissions were measured during different operational cycles for wheel loader and the data is used for both model calibration and validation. Starting from an initial emission map built from in-lab engine bench test, the model prediction of dynamic NOx emission is calibrated by three real-time engine performance parameters highly correlated to the NOx generation. Considering the characteristics of the nonroad equipment, a dynamic module is added to represent engine state transition due to frequent switching of an operational mode in construction activities, making the whole model more accurate in predicting instantaneous emission levels. Compared to the validation data randomly selected from three different cycle tests, the model shows good performance concerning prediction accuracy and with the capacity of handling drastic changes of the working condition of the machine. While the study focuses on the engine-out NOx emission the resulting methodology can be generalized for emission modeling of other nonroad construction machines.

  • 123.
    Huq, Prem
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport planning, economics and engineering.
    Cykelparkeringsplatser: Grundläggande principer för planering, lokalisering och utformning2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This bachelor thesis is about illustrating the fundamental principles for planning, locating

    and designing bicycle parking spaces. The study aims to give an understanding of the

    need and demand for bicycle parking spaces today, as well as to determine how these can

    be met according to different theories. The study also aims to investigate the issue with

    incorrectly parked bicycles, which occurs frequently in the cityscape and therefore creates

    an obstacle in street spaces.

    An observational study on the new bicycle lots along Götgatan was conducted in order

    to analyze how the theories of bicycle parking spaces are applied in practice. Cyclists

    were then interviewed in order to obtain a deeper understanding of the cyclists’ revealed

    preferences. A quantitative survey was also conducted to measure the popularity of the

    bicycle stands among the cyclists.

    The study clearly shows that the most fundamental principles, of the various theories, of

    suitable bicycle parking spaces are as follows: Planning areas intended for bicycle parking

    spaces at an early stage, locating the bicycle parking spaces as close to the target point as

    possible, as well as designing the bicycle parking spaces according to peoples needs. Well

    thought out planning, correct placement, and carefully estimated needs are key concepts

    in the establishment of attractive and frequently used bicycle parking spaces.

    The observational study revealed that there were few cyclists who chose to park their

    bicycles in the new bicycle lots on Götgatan. The interviews provided an explanation for

    why cyclists do not choose the new bicycle lots as their parking option. It was shown

    that this is due to unnecessary long walk to their target points as well as a potential safety

    risk in regards to crossing the bicycle lane in order to reach pedestrian sidewalk.

    Proximity to the target point and avoidance of crossing the bicycle lane are among the

    most fundamental principles that are illustrated by the theories and are also the most

    applied in practice.

  • 124. Ivert, Torbjorn
    et al.
    Dalen, Magnus
    Ander, Charlotte
    Stalesen, Ragnhild
    Näsman, Per
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Lordkipanidze, Marie
    Hjemdahl, Paul
    Platelet function one and three months after coronary bypass surgery in relation to once or twice daily dosing of acetylsalicylic acid2017In: Thrombosis Research, ISSN 0049-3848, E-ISSN 1879-2472, Vol. 149, p. 64-69Article in journal (Refereed)
    Abstract [en]

    Introduction: Current guidelines recommend acetylsalicylic acid (ASA) treatment after coronary artery bypass grafting (CABG) to reduce thrombotic vein graft occlusion. The optimal dosage of ASA is not known. Materials and methods: Forty-two patients undergoing elective CABG were randomized to receive either ASA 75 mg or 160 mg once daily (OD) or 75 mg twice daily (BID) after the operation. Platelet function testing was performed before, and one and three months after the operation. Results: White blood cell counts increased during the initial postoperative days whereas platelet countswere initially slightly reduced after the operation but increased after one month without any major changes of mean platelet volumes. Serum thromboxane B-2 was more effectively suppressed at one and three months after the operation with ASA 75 mg BID or 160 mg OD than with 75 mg OD (p < 0.001). ASA 75 mg BID and 160 mg OD were equally effective. Adenosine diphosphate stimulated platelet aggregation in whole blood (Multiplate (R)) was increased one and three months after the operation, and this was counteracted by ASA 75 mg BID but not by 75 or 160 mg OD. Arachidonic acid-induced aggregation was more effectively inhibited by 75 mg BID or 160 mg OD compared to 75 mg OD at three months. Conclusions: Less effective inhibition of platelet activation was obtained with ASA 75 mg OD than with ASA 160mg OD or 75mg BID up to three months after CABG. Especially the latter dose is of interest for further studies of efficacy and clinical outcomes after CABG.

  • 125. Jansson, Kjell
    et al.
    Andreasson, Ingmar
    Kottenhoff, Karl
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Public Transport in the Era of ITS: Forms of Public Transport2016In: MODELLING PUBLIC TRANSPORT PASSENGER FLOWS IN THE ERA OF INTELLIGENT TRANSPORT SYSTEMS: COST ACTION TU1004 (TRANSITS), Springer, 2016, p. 29-83Chapter in book (Refereed)
  • 126.
    Jegenberg, Minna
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Lundström, Kristina
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Fotgängares gånghastigheter i bytespunkter för kollektivtrafik2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Walking speeds are an important parameter in the process of designing for example arenas, malls

    and station environments, to be able to make them safe and comfortable for the users. Previous

    studies have mainly focused on pedestrian walking speeds at zebra crossings and the results of these

    are the basis for traffic signal timing. The studies have also investigated the relationship between

    walking speed and gender, age and density of pedestrians. From the results of these studies,

    conclusions have been drawn that these three factors have an impact on pedestrian walking speeds.

    To make microsimulations of pedestrians reflect reality as well as possible, pedestrian walking speeds

    should be investigated at regular intervals, as walking speeds change with the ongoing change of the

    composition of the population. In the simulation of station environments, pedestrian speeds should

    also be used that have been measured in these types of environments. Alternatively, the speeds

    should be measured at locations near stations, rather than using speeds from zebra crossings.

    As a step in improving the above-mentioned microsimulations, the aim of this work is to study

    walking speeds at a public transport hub during rush hour. The work also focuses on connecting

    walking speeds to each sex and level of crowding. To achieve this goal, video recordings were

    performed at the exchange point between Stockholms östra and Tekniska högskolan in Stockholm,

    Sweden, where public transport passengers change between light rail and subway.

    Analysis of the video films resulted in walking speeds which were higher than those previously

    measured at zebra crossings. The most obvious factors explaining this are the differences in the

    environment where the studies were conducted and that the walking speeds in this thesis were

    measured during rush hour. The results show that simulations of stations and locations nearby

    should not be based on walking speeds measured at zebra crossings. Analysis of the video films also

    resulted in the calculated mean walking speed of women being marginally lower than for men.

    Regarding the link between density of pedestrians and their walking speeds a conclusion can be

    drawn that at low densities pedestrians have good opportunities to freely select their own walking

    speed. The freely chosen walking speed which can thus be maintained at low densities can vary

    widely between different individuals. At higher, unlike at lower densities, it is difficult for pedestrians

    to maintain a freely chosen speed due to interactions with other pedestrians. The calculated average

    walking speed at higher densities therefor decreases as the density increases. Interactions with other

    pedestrians can either mean that a pedestrian is forced to lower the speed or that he or she must

    walk faster to keep up with the current pace.

    When analyzing the video films, several other factors effecting the walking speed could be noted. Of

    these factors, grouping of pedestrians and if the pedestrian is using a phone or carrying luggage

    could be seen to decrease the pedestrian speed.

    These factors’ impact on walking speeds was only

    superficially studied in this thesis, and no reliable conclusions can therefore be drawn.

    Keywords:

    Pedestrian walking speed, public transport traffic hub, density of pedestrians, Level of

  • 127.
    Jende, Gottfrid
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Tågföljdens betydelse i tunnelbanan2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Trängsel i kollektivtrafiken kan åtgärdas inte endast genom ökning av kapaciteten utan även genom att den befintliga kapaciteten utnyttjas mer effektivt. En jämn belastning ger dels ett effektivare resursutnyttjande, dels likartade uppehållstider vid stationer och därmed bättre förutsättningar att hålla jämna intervall mellan tågen. Det förbättrar även komforten för resenärerna och därmed kollektivtrafikens attraktivitet, genom att antalet högt belastade tåg minskar.

    På en linje med kortvändningar och flera grenar – som grön linje i Stockholms tunnelbana – är en aspekt att tågföljden anpassas så att belastningen på de enskilda tågen blir så jämn som möjligt. Om ett tåg som går en kortare sträcka går efter ett tåg som går en längre sträcka kommer det första tåget ta merparten av resenärerna på den gemensamma sträckan, utöver de resenärer som är tvungna att resa med det tåg som går den längre sträckan. Om de istället går i motsatt ordning kommer tåget som går den kortare sträckan ta merparten av resenärerna på den gemensamma sträckan, vilket ger en jämnare belastning.

    Resandet på olika tåg för några olika tågföljder har undersökts med datorprogrammet Visum. Resultaten visar att tågföljden kan stora effekter på resenärernas fördelning mellan tågen. Vid en jämförelse mellan två regelbundet återkommande tågföljder framkommer markanta skillnader beroende på om de tåg som går en kortare sträcka går före eller efter de som går en längre sträcka, allt annat lika.

    Den nuvarande trafikeringen på grön linje i Stockholms tunnelbana är inte genomgående dålig, även om den har inslag som kan anses som mindre bra. De flesta av de undersökta alternativa tågföljderna ger förbättringar i vissa eller alla avseenden, men förbättringarna är mindre än skillnaderna mellan de renodlat bra eller dåliga fallen. Större förbättringar kan uppnås endast genom en större omarbetning av trafikeringen, även om mindre förändringar ger vissa positiva effekter.

    Det är svårt att enbart med förändringar i tågföljden helt utjämna skillnaderna mellan de tåg som utgår från Vällingby och Hässelby Strand, eller att markant öka kapacitetsutnyttjandet på de tåg som utgår från Alvik och Åkeshov. Därmed kvarstår en viss ineffektivitet även i de bästa alternativen. Ytterligare ändringar kan ge större effekter än vad ändringar av tågföljden enbart kan ge, men detta har inte undersökts mer systematiskt.

  • 128.
    Jenelius, Erik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Cats, Oded
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    The Value of New Cross-Radial Links for Public Transport Network Robustness2014In: Vulnerability, Uncertainty, and Risk: Quantification, Mitigation, and Management - Proceedings of the 2nd International Conference on Vulnerability and Risk Analysis and Management, ICVRAM 2014 and the 6th International Symposium on Uncertainty Modeling and Analysis, ISUMA 2014, American Society of Civil Engineers (ASCE), 2014, p. 638-647Conference paper (Refereed)
    Abstract [en]

    The introduction of new links to network topology could potentially contribute to greater capability to withstand system breakdowns. This paper analyzes the value of adding new cross-radial links for public transport network robustness. The value is evaluated in terms of passenger welfare under disruptions. Using a model that considers passengers' dynamic travel choices, stochastic traffic conditions, timetables and capacity constraints, a new light rail transit line in Stockholm, Sweden is evaluated. The results show that: (1) the cross-radial link reduces the impacts of disruptions of critical links; and (2) the total value of robustness is positive and significantly offsets the loss in welfare caused by disruption of the cross-radial link itself. © 2014 American Society of Civil Engineers.

  • 129.
    Jenelius, Erik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Cats, Oded
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    The value of new public transport links for network robustness and redundancy2015In: Transportmetrica A: Transport Science, ISSN 2324-9935, Vol. 11, no 9, p. 819-835Article in journal (Refereed)
    Abstract [en]

    A common argument for introducing new links or services to transport networks is that they will contribute to greater capability to withstand system breakdowns. This paper presents a methodology for assessing the value of new links for public transport network robustness, considering disruptions of other lines and links as well as the new links themselves. The value is evaluated in terms of passenger welfare under disruptions and can be compared to traditional welfare benefits and investment costs. Distinction is made between the value of robustness, defined as the change in welfare during disruption compared to the baseline network, and the value of redundancy, defined as the change in welfare losses due to disruption. The paper introduces the total values of robustness and redundancy by considering a full space of scenarios and their respective frequencies. Using a model that considers passengers' dynamic travel choices, stochastic traffic conditions, timetables and capacity constraints, results are more nuanced than analyses based only on network topology and other static attributes. A new cross-radial light rail transit line in Stockholm, Sweden, is evaluated. The new link increases welfare levels under all scenarios and has a positive value of robustness. However, disruption costs increase under some scenarios and the value of redundancy is negative. In general, the value of redundancy depends on the new link's role as complement or substitute and passengers' ability to utilise spare capacity during short-term unexpected disruptions.

  • 130.
    Jenelius, Erik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport planning, economics and engineering.
    Koutsopoulos, Hans N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport planning, economics and engineering.
    Probe vehicle data sampled by time or space: Consistent travel time allocation and estimation2015In: Transportation Research Part B: Methodological, ISSN 0191-2615, E-ISSN 1879-2367, Vol. 71, p. 120-137Article in journal (Refereed)
    Abstract [en]

    A characteristic of low frequency probe vehicle data is that vehicles traverse multiple network components (e.g., links) between consecutive position samplings, creating challenges for (i) the allocation of the measured travel time to the traversed components, and (ii) the consistent estimation of component travel time distribution parameters. This paper shows that the solution to these problems depends on whether sampling is based on time (e.g., one report every minute) or space (e.g., one every 500 m). For the special case of segments with uniform space-mean speeds, explicit formulae are derived under both sampling principles for the likelihood of the measurements and the allocation of travel time. It is shown that time-based sampling is biased towards measurements where a disproportionally long time is spent on the last segment. Numerical experiments show that an incorrect likelihood formulation can lead to significantly biased parameter estimates depending on the shapes of the travel time distributions. The analysis reveals that the sampling protocol needs to be considered in travel time estimation using probe vehicle data.

  • 131.
    Jenelius, Erik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Kristoffersson, Ida
    Swedish National Road and Transport Research Institute (VTI).
    Fransson, Magnus
    Sweco Society AB.
    Validation of Traffic Simulation Models Based onthe Macroscopic Fundamental Diagram2017Conference paper (Other academic)
    Abstract [en]

    Urban traffic simulation models could benefit significantly from new validation methods with potential to reduce the time-consuming calibration and validation work needed before application of the model to evaluate city infrastructure or policy implementations. Current practice is to validate simulation models locally through comparison with point flow measurements and travel times on some important routes. However, for many applications, the level of congestion in an entire area is important. During the last decade, several studies have found empirical evidence of a relation between flow and density on city district level, the existence of a so-called macroscopic fundamental diagram (MFD). This paper shows how the MFD can be used to validate results from a traffic simulation model for a city district. Furthermore, the paper shows empirical results for Stockholm, Sweden.

  • 132.
    Jin, Junchen
    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 Decentralized Traffic Light Control System Based on Adaptive Learning2017In: IFAC-PapersOnLine, ISSN 1045-0823, E-ISSN 1797-318X, Vol. 50, no 1, p. 5301-5306Article in journal (Refereed)
    Abstract [en]

    This paper proposes a decentralized traffic light control system in a multi-agent framework. Each signal controller at an intersection is modeled as an intelligent agent capable of making actions for signal operations according to received detection information. The controller agent works with a turning movement based phasing scheme. Duration of turning movement is determined by a multi-criteria reinforcement learning algorithm. In the design of agent, both traffic mobility and energy efficiency are taken into account. Then, a case study is carried out to assess the performance of the proposed decentralized signal control system. The simulation results outperforms an optimized vehicle-actuated control system by reducing average travel delay and average fuel consumption for vehicles. In particular, the decentralized control system is queue responsive and able to adapt to demand in its green time allocation.

  • 133.
    Jin, Junchen
    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. iTekn Solutions, Sweden.
    A group-based traffic signal control with adaptive learning ability2017In: Engineering applications of artificial intelligence, ISSN 0952-1976, E-ISSN 1873-6769, Vol. 65, p. 282-293Article in journal (Refereed)
    Abstract [en]

    Group-based control is an advanced traffic signal strategy capable of dynamically generating phase sequences at intersections. Combined with the phasing scheme, vehicle actuated timing is often adopted to respond to the detected traffic. However, the parameters of a signal controller are often predetermined in practice, and the control performance may suffer from deterioration when dealing with highly fluctuating traffic demand. This study proposes a group-based signal control approach capable of making decisions based on its understanding of traffic conditions at the intersection level. In particular, the control problem is formulated using a framework of stochastic optimal control for multi-agent system in which each signal group is modeled as an intelligent agent. The agents learn how to react to traffic environment and make optimal timing decisions according to the perceived system states. Reinforcement learning, enhanced by multiple-step backups, is employed as the kernel of the intelligent control algorithm, where each agent updates its knowledge on-line based on a sequence of states during the process. In addition, the proposed system is designated to be compatible with the prevailing signal system. A case study was carried out in a simulation environment to compare the proposed control approach with a benchmark controller used in practice, group-based vehicle actuated (GBVA) controller, whose parameters were off-line optimized using a genetic algorithm. Simulation results show that the proposed adaptive group-based control system outperforms the optimized GBVA control system mainly because of its real-time adaptive learning capacity in response to the changes in traffic demand.

  • 134.
    Jin, Junchen
    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 Learning-based Adaptive Group-based Signal Control System under Oversaturated Conditions2016In: IFAC-PapersOnLine, ISSN 2405-8963, Vol. 49, no 5, p. 291-296Article in journal (Refereed)
    Abstract [en]

    The operation of traffic signal control is of significant importance in traffic management and operation practice, especially under oversaturated condition during the morning and afternoon peak hours. However, the conventional signal control systems showed the limitations in signal timing and phasing under oversaturated situations. This paper proposes a multi-agent adaptive signal control system in the context of group-based phasing techniques. The adaptive signal control system is able to acquire knowledge on-line based on the perceived traffic states and the feedback from the traffic environment. Reinforcement learning with eligibility trace is applied as the learning algorithm in the multi-agent system. As a result, the signal controller makes an intelligent timing decision. Feature-based function approximation method is incorporated into reinforcement learning framework to improve the learning efficiency as well as the quality of signal timing decisions. The learning process of the learning-based signal control is carried out with the aid of a microscopic traffic simulation model. A benchmarking system, an optimized group-based vehicle actuated signal control system, is compared with the proposed adaptive signal control systems. The simulation results show that the proposed adaptive group-based signal control system has the potential to improve the mobility efficiency under different congested situations.

  • 135.
    Jin, Junchen
    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 Learning-based Adaptive Signal Control System with Function Approximation2016In: IFAC Papers-Online, ISSN 2405-8963, Vol. 49, no 3, p. 5-10Article in journal (Refereed)
    Abstract [en]

    Traffic signal control plays a crucial role in traffic management and operation practice. In the past decade, adaptive signal control systems have shown the abilities to improve the effectiveness of the transportation system in many aspects. This paper proposes an adaptive signal control system in the context of group-based phasing techniques. The adaptive signal control system is modeled as a multi agent System capable of acquiring knowledge on-line based on the perceived traffic states and the feedback from the external environment,. Reinforcement learning is applied as the learning algorithm resulting in intelligent timing decisions. Feature based function approximation method is incorporated into the reinforcement learning framework for the purpose of improving learning efficiency as well as the quality of signal timing decisions. The assessment of such a learning-based signal control system is carried out by using an opensource microscopic traffic simulation software, SUMO. A benchmarking system, the optimized group-based vehicle actuated signal control system, compared with the learning-based signal control systems regarding mobility efficiency. The simulation results show that the proposed adaptive group based signal control system has the potential to improve the mobility efficiency regardless of the settings of traffic demands.

  • 136.
    Jin, Junchen
    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 multi-criteria intelligent control for traffic lights using reinforcement learning2018In: Advanced Concepts, Methodologies and Technologies for Transportation and Logistics, Springer Verlag , 2018, p. 438-451Chapter in book (Refereed)
    Abstract [en]

    Traffic signal control plays a crucial role in traffic management and operation practices. In the past decade, adaptive signal control systems, capable of adjusting control schemes in response to traffic patterns, have shown the abilities to improve traffic mobility. On the other hand, the negative impacts on environments by increased vehicles attract increased attentions from traffic stakeholders and the general public. Most of the prevalent adaptive signal control systems do not address energy and environmental issues. The present paper proposes an adaptive signal control system capable of taking multi-criteria strategies into account. A general multi-agent framework is introduced for modeling signal control operations. The behavior of each cognitive agent is modeled by a Constrained Markov Decision Process (CMDP). Reinforcement learning algorithms are applied to solve the MDP problem. As a result, the signal controller makes intelligent timing decisions according to a pre-defined policy goal. A case study is carried out for the stage-based control scheme to investigate the effectiveness of the adaptive signal control system from two perspectives, traffic mobility and energy efficiency. The control approach can be further applied to a large network in a decentralized manner. 

  • 137.
    Jin, Junchen
    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 multi-objective agent-based approach for road traffic controls: application for adaptive traffic signal systems2017Manuscript (preprint) (Other academic)
    Abstract [en]

    Agent-based approaches have gained popularity in engineering applications, but its potential for advanced traffic controls has not been sufficiently explored. This paper presents a multi-agent framework that models traffic control instruments and their interactions with road traffic. A multi-objective Markov decision process is applied to model agent operations, allowing agents to form a decision in the context of multiple policy goals. The problem is reformulated by a constrained Markov decision process (CMDP) to enhance the computational efficiency. In the study, the policy goal with the highest priority becomes the optimization objective, but the other objectives are transferred as constraints for optimization. A reinforcement learning based approach is developed with different function approximation methods used to enhance the control algorithm. For implementation of multi-objective control, a threshold lexicographic ordering method is introduced and integrated with the learning algorithm. While the multi-objective intelligent control method could be potentially applied for different road traffic controls, this paper demonstrates a case study on traffic signal control in a road network in Stockholm. Intersections are modeled as agents that can make intelligent timing decisions according to the detected traffic states and update their knowledge from system feedback. The evaluation results show the benefits offered by the control approach especially when multiple policy requirements are introduced.

  • 138.
    Jin, Junchen
    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 non-parametric Bayesian framework for traffic-state estimation at signalized intersections2017Manuscript (preprint) (Other academic)
    Abstract [en]

    An accurate and practical traffic-state estimation (TSE) method for signalized intersections plays an important role for real-time operations to facilitate efficient traffic management. This paper presents a generalized modeling framework for estimating traffic states at signalized intersections. The framework is non-parametric and data-driven, without the requirement on explicit models of traffic. Additionally, in principle, any type of data source together with any type of signal controller can be incorporated with the proposed framework. The Bayesian filter (BF) approach is the core of the framework and introduces a recursive state estimation process. The required transition and measurement models of the BFs are trained using Gaussian process (GP) regression models with respect to a set of historical data. A Gaussian process model uses kernel functions to describe the proximity among data points, and the hyper-parameters adopted in the GP model are optimized according to the training data. In addition to the detailed derivation of the integration of BFs and GP regression models, an algorithm based on the extended Kalman filter is presented for real-time traffic estimation. The effectiveness of the proposed framework is demonstrated through several numerical experiments using data generated in microscopic traffic simulations. Both fixed-location data (i.e., loop detector) and mobile data (i.e., connected vehicle) are examined with the framework. As a result, the method performs well for the tested traffic conditions. In particular, the estimator provides a competitive estimation accuracy merely using the position information of a small portion of vehicles at the intersection. The approach is suitable for a short-term estimation requirement, which is normally a challenging task in traffic control and operations.

  • 139.
    Jin, Junchen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Adaptive group-based signal control by reinforcement learning2015In: Transportation Research Procedia, ISSN 2324-9935, E-ISSN 2352-1465, p. 207-216Article in journal (Refereed)
    Abstract [en]

    Group-based signal control is one of the most prevalent control schemes in the European countries. The major advantage of group-based control is its capability in providing flexible phase structures. The current group-based control systems are usually implemented with rather simple timing logics, e.g. vehicle actuated logic. However, such a timing logic is not sufficient to respond to the traffic environment whose inputs, i.e. traffic demands, dynamically change over time. Therefore, the primary objective of this paper is to formulate the existing group-based signal controller as a multi-agent system. The proposed signal control system is capable of making intelligent timing decisions by utilizing machine learning techniques. In this regard, reinforcement learning is a potential solution because of its self-learning properties in a dynamic environment. This paper, thus, proposes an adaptive signal control system, enabled by a reinforcement learning algorithm, in the context of group-based phasing technique. Two different learning algorithms, Q-learning and SARSA, have been investigated and tested on a four-legged intersection. The experiments are carried out by means of an open-source traffic simulation tool, SUMO. Performances on traffic mobility of the adaptive group- based signal control systems are compared against those of a well-established group-based fixed time control system. In the testbed experiments, simulation results reveal that the learning-based adaptive signal controller outperforms group-based fixed time signal controller with regards to the improvements in traffic mobility efficiency. In addition, SARSA learning is a more suitable implementation for the proposed adaptive group-based signal control system compared to the Q-learning approach.

  • 140.
    Jin, Junchen
    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.
    Adaptive Group-Based Signal Control Using Reinforcement Learning with Eligibility Traces2015In: IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC, IEEE conference proceedings, 2015, p. 2412-2417Conference paper (Refereed)
    Abstract [en]

    Group-based signal controllers are widely deployed on urban networks in the Nordic countries. However, group-based signal controls are usually implemented with rather simple timing logics, e.g. vehicle actuated timing. In addition, group-based signal control systems with pre-defined signal parameter settings show relatively poor performances in a dynamically changed traffic environment. This study, therefore, presents an adaptive group-based signal control system capable of changing control strategies with respect to non-stationary traffic demands. In this study, signal groups are formulated as individual agents. The signal group agent learns from traffic environments and makes intelligent timing decisions according to the perceived system states. Reinforcement learning with multiple-step backups is applied as the learning algorithm. Agents on-line update their knowledge based on a sequence of states during the learning process rather than purely on the basis of single previous state. The proposed signal control system is integrated into a software-in-the-loop simulation (SILS) framework for evaluation purpose. In the testbed experiments, the proposed adaptive group-based control system is compared to a benchmark signal control system, the well-established group-based fixed-time control system. The simulation results demonstrate that learning-based and adaptive group-based signal control system owns its advantage in dealing with dynamic traffic environments in terms of improving traffic mobility efficiency.

  • 141.
    Jin, Junchen
    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.
    Implementation and Optimization of Group-based Signal Control in Traffic Simulation2014In: 2014 IEEE 17TH INTERNATIONAL CONFERENCE ON INTELLIGENT TRANSPORTATION SYSTEMS (ITSC), 2014, p. 2517-2522Conference paper (Refereed)
    Abstract [en]

    Over the past decades, group-based control has become one of the most popular signal technologies being applied in many cities around the world. LHOVRA control is one of such group-based controls widely employed in Scandinavian countries. While several previous studies showed that group-based control outperforms stage-based control in many aspects, implementation and evaluation of signal controllers are complicated in a real application. In addition, little effort has been put in optimizing such group-based controllers in traffic management practice. This study implements generic group-based control in an object-oriented software framework, while a software-in-the-loop simulation is developed to integrate the signal controller with an open-source traffic simulator, SUMO. Also, stochastic optimization is applied to generate optimal signal parameters according to different settings of objective. In particular, part of the study is to improve the computational performance of the optimization process by parallelized simulation runs. Test-based experiments are finally carried out to evaluate traffic and optimize its impact on a small traffic network in Stockholm.

  • 142.
    Jin, Junchen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport Planning, Economics and Engineering.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport Planning, Economics and Engineering.
    Johansson, Ingrid
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Heavy-duty vehicle platoons in real traffic: simulation modeling and analysisManuscript (preprint) (Other academic)
    Abstract [en]

    In freight transport systems, fuel consumption can be significantly reduced by means of heavy-duty vehicle (HDV) platooning on highways. An HDV platoon refers to a group of HDVs with small intermediate distances enabled by the HDVs being equipped by sensors and controllers. It is of importance for transport authorities and industries to explore the effects on overall traffic systems by introducing HDV platooning. Although previous studies have investigated the potential benefits of HDV platooning, the control performance and effects in real traffic have barely been explored. In the present study, a simulation platform has been developed to model and analyze the effects of HDV platoons in real traffic conditions. The simulation model is based on an open-source microscopic traffic simulator, SUMO, and calibrated using data collected by a motorway control system (MCS). The current model incorporates the vehicle dynamics of HDVs in the simulation, while an HDV in a platoon is controlled by a proportional-integral-derivative (PID) controller for its longitudinal behavior. Furthermore, the PID control parameters have been optimized for a driving cycle, according to predefined criteria, while taking vehicle dynamics and stability conditions into account. A case study has been carried out by adopting HDV platooning on a highway stretch in Sweden. The performance of the HDV platoons and effects on the other vehicles on the highway have been evaluated for different scenarios through multiple simulation runs. As a result, it is found that substantial fuel reductions have been achieved for HDVs if they form platoons in the evaluation cases. The analysis of the other vehicles shows only rather small effects when HDV platooning is implemented.

  • 143.
    Jin, Junchen
    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.
    Johansson, Ingrid
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    MODELING AND ANALYSIS OF PID-CONTROLLED HEAVY-DUTY VEHICLE PLATOONS IN REAL TRAFFIC2017Conference paper (Refereed)
  • 144.
    Jin, Junchen
    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.
    Kosonen, Iisakki
    A stochastic optimization framework for road traffic controls based on evolutionary algorithms and traffic simulation2017In: Advances in Engineering Software, ISSN 0965-9978, E-ISSN 1873-5339, Vol. 114, p. 348-360Article in journal (Refereed)
    Abstract [en]

    Traffic flow is considered as a stochastic process in road traffic modeling. Computer simulation is a widely used tool to represent traffic system in engineering applications. The increased traffic congestion in urban areas and their impacts require more efficient controls and management. While the effectiveness of control schemes highly depends on accurate traffic model and appropriate control settings, optimization techniques play a central role for determining the control parameters in traffic planning and management applications. However, there is still a lack of research effort on the scientific computing framework for optimizing traffic control and operations and facilitating real planning and management applications. To this end, the present study proposes a model-based optimization framework to integrate essential components for solving road traffic control problems in general. In particular, the framework is based on traffic simulation models, while the solution needs extensive computation during the engineering optimization process. In this work, an advanced genetic algorithm, extended by an external archive for storing globally elite genes, governs the computing framework, and in application it is further enhanced by a sampling approach for initial population and utilizations of adaptive crossover and mutation probabilities. The final algorithm shows superior performance than the ordinary genetic algorithm because of the reduced number of fitness function evaluations in engineering applications. To evaluate the optimization algorithm and validate the whole software framework, this paper illustrates a detailed application for optimization of traffic light controls. The study optimizes a simple road network of two intersections in Stockholm to demonstrate the model-based optimization processes as well as to evaluate the presented algorithm and software performance.

  • 145.
    Jin, Junchen
    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.
    Kosonen, Iisakki
    An intelligent control system for traffic lights with simulation-based evaluation2017In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 58, p. 24-33Article in journal (Refereed)
    Abstract [en]

    This paper introduces an intelligent control system for traffic signal applications, called Fuzzy Intelligent Traffic Signal (FITS) control. It provides a convenient and economic approach to improve existing traffic light infrastructure. The control system is programmed on an intermediate hardware device capable of receiving messages from signal controller hardware as well as overriding traffic light indications during real-time operations. Signal control and optimization toolboxes are integrated into the embedded software in the FITS hardware device. A fuzzy logic based control has been implemented in FITS. In order to evaluate the effects of FITS system, this study attempts to develop a computational framework to evaluate FITS system using microscopic traffic simulation. A case study is carried out, comparing different commonly used signal control strategies with the FITS control approach. The simulation results show that the control system has the potential to improve traffic mobility, compared to all of the tested signal control strategies, due to its ability in generating flexible phase structures and making intelligent timing decisions. In addition, the effects of detector malfunction are also investigated in this study. The experiment results show that FITS exhibits superior performance than several other controllers when a few detectors are out-of-order due to its self-diagnostics feature.

  • 146. Joewono, T. B.
    et al.
    Vandebona, U.
    Susilo, Yusak O.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Behavioural Causes and Categories of Traffic Violations by Motorcyclists in Indonesian Urban Roads2015In: Journal of Transportation Safety and Security, ISSN 1943-9962, Vol. 7, no 2, p. 174-197Article in journal (Refereed)
    Abstract [en]

    To prevent road accidents and formulate policies to promote road safety in urban roads, it is crucial to understand factors that cause violation of traffic rules. Although such issues have been investigated in developed countries, the availability of such knowledge in rapidly motorizing countries, such as Indonesia, is still poor. This study aims to investigate the factors influencing violation behavior by motorcyclists and types of such violations. The study is based on surveys of three metropolitan cities, namely Bandung, Yogyakarta, and Surabaya, in Indonesia. Structural equation modelling has been performed to investigate factors influencing motorcyclists to commit traffic violations and their causal relationships. Although there are differences in the ranking of factors influencing traffic violations among the three cities studied, the analysis has been able to show patterns of similarities as well. The inadequacy of engineering and maintenance conditions of the road infrastructure appears to be partly responsible for the phenomenon of motorcyclists developing a lack of respect to traffic rules.

  • 147. Johansson, I.
    et al.
    Dahlstrom, U.
    Edner, M.
    Näsman, Per
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Ryden, L.
    Norhammar, A.
    Glycosylated haemoglobin predicts mortality in patients with heart failure and unknown diabetes: insights from the Swedish Heart Failure registry (SwedeHF)2016In: Diabetologia, ISSN 0012-186X, E-ISSN 1432-0428, Vol. 59, p. S532-S532Article in journal (Refereed)
  • 148. Johansson, I.
    et al.
    Dahlström, U.
    Edner, M.
    Näsman, Per
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Ryden, L.
    Norhammar, A.
    Glycosylated haemoglobin predicts mortality in patients with heart failure and unknown diabetes: insights from the Swedish heart failure registry (SwedeHF)2016In: EUROPEAN HEART JOURNAL, ISSN 0195-668X, Vol. 37, p. 733-733Article in journal (Refereed)
  • 149. Johansson, I.
    et al.
    Dahlström, U.
    Edner, M.
    Näsman, Per
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Rydén, L.
    Norhammar, A.
    Prognostic Implications of Type 2 Diabetes Mellitus in Ischemic and Nonischemic Heart Failure2016In: Journal of the American College of Cardiology, ISSN 0735-1097, E-ISSN 1558-3597, Vol. 68, no 13, p. 1404-1416Article in journal (Refereed)
    Abstract [en]

    Background Heart failure (HF) is a common and serious complication in type 2 diabetes mellitus (T2DM). The prognosis of ischemic HF and impact of revascularization in such patients have not been investigated fully in a patient population representing everyday practice. Objectives This study examined the impact of ischemic versus nonischemic HF and previous revascularization on long-term prognosis in an unselected population of patients with and without T2DM. Methods Patients stratified by diabetes status and ischemic or nonischemic HF and history of revascularization in the Swedish Heart Failure Registry (SwedeHF) from 2003 to 2011 were followed up for mortality predictors and longevity. A propensity score analysis was applied to evaluate the impact of previous revascularization. Results Among 35,163 HF patients, those with T2DM were younger, and 90% had 1 or more associated comorbidities. Ischemic heart disease (IHD) occurred in 62% of patients with T2DM and 47% of those without T2DM, of whom 53% and 48%, respectively, had previously undergone revascularization. T2DM predicted mortality regardless of the presence of IHD, with adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) of 1.40 (1.33 to 1.46) and 1.30 (1.22 to 1.39) in those with and without IHD, respectively. Patients with both T2DM and IHD had the highest mortality, which was further accentuated by the absence of previous revascularization (adjusted HR: 0.82 in favor of such treatment; 95% CI: 0.75 to 0.91). Propensity score adjustment did not change these results (HR: 0.87; 95% CI: 0.78 to 0.96). Revascularization did not abolish the impact of T2DM, which predicted mortality in those with (HR: 1.36; 95% CI: 1.24 to 1.48) and without (HR: 1.45; 95% CI: 1.33 to 1.56) a history of revascularization. Conclusions Ninety percent of HF patients with T2DM have preventable comorbidities. IHD in patients with T2DM had an especially negative influence on mortality, an impact that was beneficially influenced by previous revascularization.

  • 150. Johansson, I.
    et al.
    Edner, M.
    Näsman, Per
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Dahlstrom, U.
    Ryden, L.
    Norhammar, A.
    Impact of diabetes mellitus on heart failure with reduced ejection fraction: a Swedish registry based analysis2015In: European Heart Journal, ISSN 0195-668X, E-ISSN 1522-9645, Vol. 36, p. 877-877Article in journal (Other academic)
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