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  • 51.
    Cats, Oded
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR. KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Toledo, Tomer
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Evaluation of real-time holding strategies for improved bus service reliability2010In: IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC, Madeira, Portugal, 2010, p. 718-723Conference paper (Refereed)
    Abstract [en]

    Service reliability is one of the main measures of performance determining transit system level of service. Holding control strategies are a common transit operations practice aimed to reduce transit service unreliability by setting criteria for departure fromtime point stops. In order to adequately analyze the sources of uncertainty involved with transit performance, it is essential to model dynamically the interactions between traffic conditions, passenger demand and transit operations. BusMezzo, a transit simulation model has been developed on a platform of a mesoscopic traffic simulation model, which enables the representation of large-scale transit systems. The model implements severalreal-time holding strategies. It is used to evaluate the application of these strategies in areal-world high-demand bus line in the Tel Aviv metropolitan area, under various scenarios. An analysis of the results suggests that a holding strategy based on the mean headway from the preceding bus and the next bus, restricted by a maximum allowableholding time, is especially efficient. 

  • 52.
    Cats, Oded
    et al.
    Faculty of Civil and Environmental Engineering, Technion-Israel Institute of Technology, Haifa.
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301). KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Toledo, Tomer
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301).
    Mesoscopic modeling of bus public transportation2010Conference paper (Refereed)
  • 53.
    Cats, Oded
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Toledo, Tomer
    Technion - Israel Institute of Technology.
    Koutsopoulos, Haris N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis.
    Modeling real-time transit information and its impacts on travelers’ decisions2012In: Proceedings of the Transportation Research Board 91st Annual Meeting., 2012Conference paper (Refereed)
  • 54.
    Cats, Oded
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Koutsopoulos, Harilaos
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Toledo, Tomer
    Technion - Israel Institute of Technology.
    Adaptive path choice decisions in public transport systems: an agent-based assignment model2012Conference paper (Refereed)
  • 55.
    Cats, Oded
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR. KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Toledo, Tomer
    Evaluating the role of real-time transit information provision on dynamic passenger path choice2012In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052Article in journal (Refereed)
  • 56.
    Cats, Oded
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Larijani, Anahid
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Impacts of holding control strategies on transit performance: A bus simulation model analysis2011In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, no 2216, p. 51-58Article in journal (Refereed)
    Abstract [en]

    Transit operators are interested in strategies to improve service reliability as it is an important measure of performance and level of service. One of the common practices aimed at reducing service unreliability is holding control strategies. The design of these strategies involves the selection of a set of time point stops and the holding criteria for regulating the departure time. The interactions between passenger activity, transit operations, and traffic dynamics must be dynamically modeled to analyze the impacts of holding strategies on transit performance. An evaluation of different holding criteria and the number and location of time point stops was conducted with Bus Mezzo, a dynamic transit simulation model. The holding strategies were implemented in the model and applied to a high-frequency trunk bus line in Stockholm, Sweden. The analysis of the results considers the implications of holding strategies from both passenger and operator perspectives. The analysis suggests substantial gains are possible by implementing a holding strategy on the basis of the mean headway from the preceding and the succeeding buses. This strategy is the most efficient for passenger time savings as well as fleet costs and crew management.

  • 57.
    Cats, Oded
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Larijani, Anahid Nabavi
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Ólafsdóttir, Ásdís
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Andréasson, Ingmar J.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Koutsopoulos, Harilaos N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Bus-Holding Control Strategies Simulation-Based Evaluation and Guidelines for Implementation2012In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, no 2274, p. 100-108Article in journal (Refereed)
    Abstract [en]

    Transit operations involve several inherent sources of uncertainty, including dispatch time from the origin terminal, travel time between stops, and dwell time at stops. Bus-holding control strategies are a prominent method applied by transit operators to improve transit performance and level of service. The common practice is to regulate departures from a limited number of stops by holding buses until their scheduled departure time. An analysis of the performance of a high-frequency bus line in Stockholm, Sweden, based on automatic vehicle location data showed that this control strategy was not effective in improving service regularity along the line. The analysis also indicated that drivers adjusted their speed according to performance objectives. Implications of a control strategy that regulates departures from all stops on the basis of the headways of the preceding bus and the following bus were evaluated with Bus Mezzo, a transit operations simulation model. The results suggest that this strategy can improve service performance considerably from both passengers' and operator's perspectives. In addition, the strategy implies cooperative operations, as the decisions of each driver are interdependent with other drivers' decisions, and mutual corrections can be made. Difficulties in realizing the benefits of the proposed strategy in practice, such as dispatching from the origin terminal, driver scheduling, and compliance, are discussed. The implications of several practical considerations are assessed by conducting a sensitivity analysis as part of the preparations for a field experiment designed to test the proposed control strategy.

  • 58.
    Cats, Oded
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Rufi, F. M.
    Koutsopoulos, Harilaos
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Optimizing the number and location of time point stops2014In: Public Transport, ISSN 1866-749X, E-ISSN 1613-7159, Vol. 6, no 3, p. 215-235Article in journal (Refereed)
    Abstract [en]

    Public transport service is subject to multiple sources of uncertainty that impact its reliability. Holding control strategies are a common method to prevent the deterioration of service reliability along the route. This paper expands on previous studies by considering the general case of determining both the optimal number and optimal location of the time point stops (TPS) where holding takes place, and assessing their impacts on transit performance using simulation. Holding times are determined based on a real-time headway-based holding strategy designed to improve service regularity by seeking uniform headways along the route. The evaluation of the performance of alternative TPS layouts is simulation-based, using BusMezzo, a transit operations simulation model which models the dynamic performance of bus transit systems. The proposed framework also considers the multiple objectives incorporating passenger and operator points of view. The simulation-based optimization framework was applied in a case study with one of the premium bus lines in Stockholm, Sweden, using two solution methods—greedy and genetic algorithms. A multi-objective evaluation was conducted considering both passenger and operator perspectives. The results demonstrate that transit performance varies considerably with alternative TPS layouts. The best solution obtained by the proposed methodology reduces total weighted passenger journey times and cycle times compared to both the current layout and the case of no holding control. The proposed method could assist transit agencies and operators in evaluating and recommending alternative time point layouts.

  • 59. Dixon, Matthew
    et al.
    Koutsopoulos, Haris
    Northeastern University.
    Rabhee, Adam
    Wilson, Nigel
    Analysis of Rail Transit Operations with Rail Track Circuit Occupancy Data2007In: TRB 86th Annual Meeting Compendium of Papers, 2007Conference paper (Refereed)
    Abstract [en]

    Transit agencies have made a significant investment in centralized operations control systems (OCS) for their rail transit lines. In addition to their important role in safety and management of transit operations, OCSs collect and store volumes of data related to the movement of trains through the system. Based on the activation/deactivation times recorded for each block by OCS, useful information, such as headway and travel time distributions, schedule adherence, and even vehicle trajectories can be extracted. This information can then be used for service monitoring, design of more effective service maintenance strategies, and operations planning and schedule design. The paper demonstrates the use of the data through a case study of MBTA’s Red Line.

  • 60.
    Farah, Haneen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Impact of Cooperative Systems on Drivers' Car-Following Behavior2012In: TRB 91st Annual Meeting Compendium of Papers, 2012Conference paper (Refereed)
    Abstract [en]

    In-vehicle technologies and co-operative services are designed to ultimately reduce congestion and increase traffic safety. This paper investigates the impact of an infrastructure-to-vehicle co-operative system on drivers’ car-following behavior. Car following behavior, which describes the behavior of a vehicle while following the vehicle in front of it, has a significant impact on traffic performance, safety, and air pollution. In addition, it is an essential component of microsimulation models. Twenty nine test drivers drove an instrumented vehicle twice with and without the system. Trajectory data of each vehicle and the vehicle in front were collected. Car-following models were estimated for both cases, with and without the system, and the results of the two models were compared. The results show that co-operative systems have a positive impact on drivers’ car-following behavior. The system harmonizes the driving behavior of drivers and reduces the range of acceleration and deceleration differences among them. The impact of the system is larger on older drivers compared to younger drivers.

  • 61.
    Farah, Haneen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Infrastructure-to-Vehicle Communications: Impact on Driver Behavior and Safety from a European Demonstration Project2011Article in journal (Other academic)
  • 62.
    Farah, Haneen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Koutsopoulos, Haris N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Do cooperative systems make drivers' car-following behavior safer?2014In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 41, p. 61-72Article in journal (Refereed)
    Abstract [en]

    The main goal of in-vehicle technologies and co-operative services is to reduce congestion and increase traffic safety. This is achieved by alerting drivers on risky traffic conditions ahead of them and by exchanging traffic and safety related information for the particular road segment with nearby vehicles. Road capacity, level of service, safety, and air pollution are impacted to a large extent by car-following behavior of drivers. Car-following behavior is an essential component of micro-simulation models. This paper investigates the impact of an infrastructure-to-vehicle (I2V) co-operative system on drivers' car-following behavior. Test drivers in this experiment drove an instrumented vehicle with and without the system. Collected trajectory data of the subject vehicle and the vehicle in front, as well as socio-demographic characteristics of the test drivers were used to estimate car-following models capturing their driving behavior with and without the I2V system. The results show that the co-operative system harmonized the behavior of drivers and reduced the range of acceleration and deceleration differences among them. The observed impact of the system was largest on the older group of drivers.

  • 63.
    Farah, Haneen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Saifuzzaman, Mohammad
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Kölbl, Robert
    Fuchs, Susanne
    Bankosegger, Doris
    Evaluation of the effect of cooperative infrastructure-to-vehicle systems on driver behavior2012In: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 21, no 1, p. 42-56Article in journal (Refereed)
    Abstract [en]

    In-vehicle technologies and co-operative services have potential to ease congestion problems and improve traffic safety. This paper investigates the impact of infrastructure-to-vehicle co-operative systems, case of CO-OPerative SystEms for Intelligent Road Safety (COOPERS), on driver behavior. Thirty-five test drivers drove an instrumented vehicle, twice, with and without the system. Data related to driving behavior, physiological measurements, and user acceptance was collected. A macro-level approach was used to evaluate the potential impact of such systems on driver behavior and traffic safety. The results in terms of speeds, following gaps, and physiological measurements indicate a positive impact. Furthermore, drivers' opinions show that the system is in general acceptable and useful.

  • 64.
    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.

  • 65. Gordon, Jason B.
    et al.
    Koutsopoulos, Harilaos N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Wilson, Nigel H. M.
    Attanucci, John P.
    Automated Inference of Linked Transit Journeys in London Using Fare-Transaction and Vehicle Location Data2013In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, no 2343, p. 17-24Article in journal (Refereed)
    Abstract [en]

    Urban public transit providers historically have planned and managed their networks and services with little knowledge of their customers' travel patterns. Although ticket gates and bus fareboxes yield counts of passenger activity in specific stations or vehicles, the relationships between these transactions-the origins, transfers, and destinations of individual passengers-typically have been acquired only through small, costly, and infrequent rider surveys. New methods for inferring the journeys of all riders on a large public transit network have been built on recent work into the use of automated fare collection and vehicle location systems for analysis of passenger behavior. Complete daily sets of data from London's Oyster farecard and the iBus vehicle location system were used to infer boarding and alighting times and locations for individual bus passengers and to infer transfers between passenger trips of various public modes, and origin-destination matrices of linked intermodal transit journeys that include the estimated flows of passengers not using farecards were constructed. The outputs were validated against surveys and traditional origin-destination matrices. The software implementation demonstrated that the procedure is efficient enough to be performed daily, allowing transit providers to observe travel behavior on all services at all times.

  • 66.
    Huang, Zhen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    A numerical optimization approach for calibration of dynamic emission models based on aggregate estimation of ARTEMIS2010In: IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC, 2010, p. 1221-1226Conference paper (Refereed)
    Abstract [en]

    In this paper, we propose a numerical approach to calibrate dynamic emission models when on-road or in-lab instantaneous emission measurements are not fully available. Microscopic traffic simulation is applied to generate dynamic vehicle states in the second-by-second level. Using aggregate estimation of ARTEMIS as a standard reference, a numerical optimization scheme on the basis of a stochastic gradient approximation algorithm is applied to find optimal parameters for the dynamic emission model. The calibrated model has been validated on several road networks with traffic states generated by the same simulation model. The results show that with proper formulation of the optimization objective function the estimated dynamic emission model can reasonably capture the trends of online emissions of traffic fleets.

  • 67.
    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.

  • 68.
    Jenelius, Erik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS. KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Consistent travel time estimation using sparse probe vehicle data sampled by time and distance2012Report (Other academic)
  • 69.
    Jenelius, Erik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS. KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport and Location Analysis.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Time-based vs. distance-based sampling in probe vehicle data: Implications for travel time estimation2012In: Proceedings of 17th International Conference of Hong Kong Society for Transportation Studies, Hong Kong, 2012Conference paper (Refereed)
    Abstract [en]

    This paper analyses the role of the sampling protocol for travel time estimation with low frequency probe vehicle data by likelihood-based methods, such as maximum likelihood or Bayesian estimation. In the literature, there are reported cases where the vehicle positions are sampled at either certain time intervals, say, every minute, or at certain distance intervals, say, every 500 meters. We show that whether sampling is distance-based or time-based determines the proper formulation of the likelihood function. Furthermore, an incorrect likelihood formulation (for example, treating sampling as distance-based when it is time-based in actuality) often leads to biased parameter estimates. For the special case in which the path is partitioned into segments with constant, independent travel speeds we derive explicit formulas for the likelihood function for each of the two sampling principles. We also study the consistency and bias of the estimators in numerical experiments. 

  • 70.
    Jenelius, Erik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science. Department of Civil and Environmental Engineering, Northeastern University, Boston, MA 02115 USA.
    Urban network travel time prediction based on a probabilistic principal component analysis model of probe data2018In: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 19, no 2, p. 436-445Article in journal (Refereed)
    Abstract [en]

    This paper proposes a network travel time prediction methodology based on probe data. The model is intended as a tool for traffic management, trip planning, and online vehicle routing, and is designed to be efficient and scalable in calibration and real-time prediction; flexible to changes in network, data, and model extensions; and robust against noisy and missing data. A multivariate probabilistic principal component analysis (PPCA) model is proposed. Spatio-temporal correlations are inferred from historical data based on MLE and an efficient EM algorithm for handling missing data. Prediction is performed in real time by computing the expected distribution of link travel times in future time intervals, conditional on recent current-day observations. A generalization of the methodology partitions the network and applies a distinct PPCA model to each subnetwork. The methodology is applied to the network of downtown Shenzhen, China, using taxi probe data. The model captures variability over months and weekdays as well as other factors. Prediction with PPCA outperforms k-nearest neighbors prediction for horizons from 15 to 45 min, and a hybrid method of PPCA and local smoothing provides the highest accuracy.

  • 71.
    Jenelius, Erik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Transport Studies, CTS.
    Koutsopoulos, Haris N.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport Planning, Economics and Engineering.
    TIME-BASED VS. DISTANCE-BASED SAMPLING IN PROBE VEHICLE DATA: IMPLICATIONS FOR TRAVEL TIME ESTIMATION2012In: TRANSPORTATION & LOGISTICS MANAGEMENT / [ed] Mak, HY Lo, HK, HONG KONG SOC TRANSPORTATION STUDIES LTD , 2012, p. 185-192Conference paper (Refereed)
    Abstract [en]

    This paper analyses the role of the sampling protocol for travel time estimation with low frequency probe vehicle data by likelihood-based methods, such as maximum likelihood or Bayesian estimation. In the literature, there are reported cases where the vehicle positions are sampled at either certain time intervals, say, every minute, or at certain distance intervals, say, every 500 meters. We show that whether sampling is distance-based or time-based determines the proper formulation of the likelihood function. Furthermore, an incorrect likelihood formulation (for example, treating sampling as distance-based when it is time-based in actuality) often leads to biased parameter estimates. For the special case in which the path is partitioned into segments with constant, independent travel speeds we derive explicit formulas for the likelihood function for each of the two sampling principles. We also study the consistency and bias of the estimators in numerical experiments.

  • 72.
    Jenelius, Erik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Koutsopoulos, Haris N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Travel time estimation for urban road networks using low frequency probe vehicle data2013In: Transportation Research Part B: Methodological, ISSN 0191-2615, E-ISSN 1879-2367, Vol. 53, p. 64-81Article in journal (Refereed)
    Abstract [en]

    The paper presents a statistical model for urban road network travel time estimation using vehicle trajectories obtained from low frequency GPS probes as observations, where the vehicles typically cover multiple network links between reports. The network model separates trip travel times into link travel times and intersection delays and allows correlation between travel times on different network links based on a spatial moving average (SMA) structure. The observation model presents a way to estimate the parameters of the network model, including the correlation structure, through low frequency sampling of vehicle traces. Link-specific effects are combined with link attributes (speed limit, functional class, etc.) and trip conditions (day of week, season, weather, etc.) as explanatory variables. The approach captures the underlying factors behind spatial and temporal variations in speeds, which is useful for traffic management, planning and forecasting. The model is estimated using maximum likelihood. The model is applied in a case study for the network of Stockholm, Sweden. Link attributes and trip conditions (including recent snowfall) have significant effects on travel times and there is significant positive correlation between segments. The case study highlights the potential of using sparse probe vehicle data for monitoring the performance of the urban transport system.

  • 73.
    Jenelius, Erik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Rahmani, Mahmood
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Travel time estimation for urban road networks using low frequency GPS probes2012Conference paper (Refereed)
  • 74.
    Kazagli, Evanthia
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Koutsopoulos, Haris N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Estimation of Arterial Travel Time from Automatic Number Plate Recognition Data2013In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, no 2391, p. 22-31Article in journal (Refereed)
    Abstract [en]

    Automatic vehicle identification (AVI) systems are increasingly used for the collection of traffic data in urban and freeway networks. Several methods have been proposed for the estimation of travel times from AVI data, mainly for freeways. The problem of estimation of travel times in urban networks was examined. The main difference between freeway and urban networks is that urban network AVI data are often extremely noisy. A major part of that noise is attributed to vehicles that do not traverse the monitored section directly but stop for various reasons. A mixture model was proposed to capture the underlying states of the measurements of AVI travel times in urban areas. The hypothesis was that travel times are drawn from two (or more) populations, one representing normal movement through the network and one representing vehicles that stop for whatever reason. The method was applied with AVI data (collected through a system for automatic recognition of number plates) from a number of corridors in central Stockholm, Sweden. The model was estimated as a mixture-of two lognormal distributions, and bootstrap standard errors were calculated. The results illustrate the robustness of the method and its ability to identify the underlying distribution of the latent populations consistent with the characteristics of each route, while standard methods for outlier removal fail.

  • 75.
    Koutsopoulos, Haris
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Bang, K.
    6th International Symposium on Highway Capacity and Quality of Service2011Conference proceedings (editor) (Refereed)
  • 76.
    Koutsopoulos, Haris
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Ben-Akiva, Moshe
    MIT.
    Advanced Public Transport Systems: Simulation-Based Evaluation2012In: Encyclopedia of Sustainability Science and Technology / [ed] Meyers, Robert A, Springer , 2012, p. 90-110Chapter in book (Refereed)
  • 77.
    Koutsopoulos, Haris N.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Farah, Haneen
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Latent Class Model for Car Following Behavior2012In: Transportation Research Part B: Methodological, ISSN 0191-2615, E-ISSN 1879-2367, Vol. 46, no 5, p. 563-578Article in journal (Refereed)
    Abstract [en]

    Car-following behavior, which describes the behavior of a vehicle while following the vehicle in front of it, has a significant impact on traffic performance, safety, and air pollution. In addition, car-following is an essential component of micro-simulation models. Over the last decade the use of microscopic simulation models as a tool for investigating traffic systems, ITS applications, and emission impacts, is becoming increasingly popular. The paper presents a flexible framework for modeling car-following behavior that relaxes some limitations and assumptions of the most commonly used car following models. The proposed approach recognizes different regimes in driving such as car-following, free-flow, emergency stopping, and incorporates different decisions in each regime, such as acceleration, deceleration, and do-nothing depending on the situation. A case study using NGSIM vehicle trajectory data is used to illustrate the proposed model structure. Statistical tests suggest that the model performs better than previous models.

  • 78.
    Koutsopoulos, Haris N.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301).
    Wang, Zhigao
    Simulation of Urban Rail Operations: Application Framework2007In: Transportation Research Record, ISSN 0361-1981, E-ISSN 2169-4052, no 2006, p. 84-91Article in journal (Refereed)
    Abstract [en]

    Simulation models of urban rail operations are valuable tools for analysis of the operations of complex rail transit systems. A framework is presented for the application of rail simulation that includes calibration, validation, evaluation methodology, and interpretation of results. Methods that can be used at each step to facilitate the application are discussed. In particular, approaches are presented for calibration of model parameters and inputs, such as dynamic arrival and alighting rates at stations. Application of simulation tools can be greatly enhanced by the use of train circuit occupancy data collected by automated control systems. A new rail simulation model, SimMetro, specifically designed for service performance analysis taking into account the major sources of uncertainty in operations, is also presented. A case study is used to illustrate the applicability of the proposed framework in testing alternative real-time control strategies.

  • 79.
    Koutsopoulos, Haris
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Wang, Zhigao
    An Urban Rail Operations and Control Simulator: Implementation, Calibration and Application2008In: Traffic Simulation, EPFL Press , 2008Chapter in book (Refereed)
  • 80.
    Koutsopoulos, Haris
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Wang, Zhigao
    Simulation of Urban Rail Operations: Application Framework2007Conference paper (Refereed)
  • 81.
    Koutsopoulos, Haris
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Wang, Zhigao
    Simulation of Urban Rail Operations: Models and Applications2007Conference paper (Refereed)
  • 82.
    Kusuma, Andyka
    et al.
    Univ Indonesia, Dept Civil Engn, Kampus Baru UI, Depok 16424, Indonesia..
    Koutsopoulos, Haris N.
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301).
    Critical Gap Analysis of Dual Lane Roundabouts2011In: 6TH INTERNATIONAL SYMPOSIUM ON HIGHWAY CAPACITY AND QUALITY OF SERVICE / [ed] Koutsopoulos, HN Bang, KL, ELSEVIER SCIENCE BV , 2011, Vol. 16, p. 709-717Conference paper (Refereed)
    Abstract [en]

    Roundabouts are increasingly popular because of their performance in terms of safety, capacity, and cost. Roundabouts have the potential to reduce accident risk since the traffic flows merge and diverge at small angles, and low speeds. Under certain conditions, roundabouts also improve the flow of traffic at the intersection, compared to other choices. In this paper we present a methodology for estimating an important input in the calculation of the capacity of roundabouts: the critical gap. The critical gap is the smallest gap that a driver is willing to accept to merge with the circulating traffic and mainly determines the gap acceptance behavior of the driver. The critical gap is not directly observable. Only gaps that drivers have accepted or rejected are observed. These gaps define upper and lower values for the underlying critical gap but not its exact value. The paper builds on previous literature proposing a rigorous statistical methodology for the estimation of the critical gap, and demonstrates its application through field measurements. It is assumed that the critical gap has a lognormal distribution among the driver population with a mean value that is a function of a number of explanatory variables. Based on these assumptions the critical gap and its distribution can then be estimated using maximum likelihood. A case study in a dual lane roundabout in Stockholm is used to illustrate the proposed methodology using video and other data. The results show that the critical gap depends, among other factors, on the target lane (near or far), the type of the vehicle. The results are aslo compared to values recommended by other studies.

  • 83.
    Ma, Xiaoliang
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics.
    Burghout, Wilco
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics.
    Andreasson, Ingmar
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics.
    Koutsopoulos, Haris N.
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics.
    Evaluation of Real-Time Travel Time Estimation Methods and Disruption Warning Using Noisy Automatic Vehicle Identification Measurements2009In: Transportation Research Board Annual Meeting 2009 Paper: Transportation Research Board 88th Annual Meeting, Washington D.C., Jan. 2009, 2009Conference paper (Refereed)
    Abstract [en]

    To support the implementation of a real-time traffic information system in Stockholm using automatic vehicle identification (AVI) data, a travel time analysis platform has been developed. The platform is composed of a client-side travel time data analysis program and a database server where historical travel time data are stored. In the study, several existing freeway travel time estimation algorithms and their modifications were implemented in the travel time analysis program, and evaluated using four months data collected on urban streets and arterials in and near the city of Stockholm. The advantages and disadvantages of those algorithms are analyzed using the highly noisy travel time measurements. The results show that with modifications in the parameter settings and the algorithms themselves, the methods are capable of estimating the travel times from the noise-corrupted urban data. In addition to the travel time estimation, the paper presents a simple data disruption recognition approach on the way toward a more comprehensive disruption and incident warning system.

  • 84.
    Ma, Xiaoliang
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Huang, Zhen
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    A Numerical Approach on Model Calibration for An Emission Simulation Platform2011Conference paper (Refereed)
  • 85.
    Ma, Xiaoliang
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Huang, Zhen
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Integrated Traffic and Emission Simulation: a Model Calibration Approach Using Aggregate Information2014In: Environmental Modelling and Assessment, ISSN 1420-2026, E-ISSN 1573-2967, Vol. 19, no 4, p. 271-282Article in journal (Refereed)
    Abstract [en]

    Environmental impacts of road traffic have attracted increasing attention in project-level traffic planning and management. The conventional approach considers emission impact analysis as a separate process in addition to traffic modeling. This paper first introduces our research effort to integrate traffic, emission, and dispersion processes into a common distributed computational framework, which makes it efficient to quantify and analyze correlations among dynamic traffic conditions, emission impacts, and air quality consequences. A model calibration approach is particularly proposed when on-road or in-lab instantaneous emission measurements are not directly available. Microscopic traffic simulation is applied to generate dynamic vehicle states at the second-by-second level. Using aggregate emission estimation as standard reference, a numerical optimization scheme on the basis of a stochastic gradient approximation algorithm is applied to find optimal parameters for the dynamic emission model. The calibrated model has been validated on several road networks with traffic states generated by the same simulation model. The results show that with proper formulation of the optimization objective function, the estimated dynamic emission model can capture the trends of aggregate emission patterns of traffic fleets and predict local emission and air quality at higher temporal and spatial resolutions.

  • 86.
    Ma, Xiaoliang
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301). KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Koutsopoulos, Harilaos
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301).
    A New Online Travel Time Estimation Approach using Distorted Automatic Vehicle Identification Data2008In: PROCEEDINGS OF THE 11TH INTERNATIONAL IEEE CONFERENCE ON INTELLIGENT TRANSPORTATION SYSTEMS    , 2008, p. 204-209Conference paper (Refereed)
    Abstract [en]

    Online travel time estimation is an important procedure for real-time traffic information systems (RTIS). In this paper, we describe a preliminary travel time data collection and estimation platform developed for RTIS application based on automated vehicle identification technique deployed in the Stockholm city area. The platform is composed of a client-side travel time analysis program and a database server. To obtain accurate real-time link travel times for traffic state prediction and RTIS applications, an optimal filtering algorithm is developed and evaluated using travel time data collected on urban streets in and near the city of Stockholm. The proposed algorithm shows reliable performance against the highly noisy traffic context, and is more robust than existing online travel time estimation algorithms. The estimated travel time information provides a solid basis for advanced traffic information system applications.

  • 87.
    Ma, Xiaoliang
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Koutsopoulos, Harilaos
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301).
    Estimation of the automatic vehicle identification based spatial travel time information collected in Stockholm2010In: IET Intelligent Transport Systems, ISSN 1751-956X, E-ISSN 1751-9578, Vol. 4, no 4, p. 298-306Article in journal (Refereed)
    Abstract [en]

    To support the implementation of real-time traffic information systems in the Stockholm city area using automatic vehicle identification (AVI) data, a preliminary travel time analysis tool has been developed. The program can manage and analyse travel time measurements in a distributed database server where both online and historical traffic information are saved. Meanwhile, several existing travel time estimation algorithms are implemented in the travel time analysis program, and are evaluated using four months of AVI data collected in the urban streets and arterials of and near the Stockholm downtown area. The advantages and disadvantages of those algorithms are also analysed using the highly noisy travel time measurements collected under the urban context. In addition, the authors have also evaluated a common statistical median filtering approach and suggested some modifications for AVI data estimation. In general, all these algorithms have the potential to be applied for real daily travel time estimation and the statistical median filter with modifications has been suggested for historical travel time estimation in real application. Finally, the authors point out an essential problem in travel time estimation and suggest a direction that may have the potential to improve the online traffic information quality.

  • 88.
    Ma, Xiaoliang
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Koutsopoulos, Harilaos
    KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    THE CAMERA BASED SPATIAL TRAVEL TIME INFORMATION: ANALYSIS PLATFORM AND ESTIMATION APPROACHES2010In: TRANSPORTATION AND URBAN SUSTAINABILITY, HONG KONG: HONG KONG SOC TRANSPORTATION STUDIES LTD , 2010, p. 585-592Conference paper (Refereed)
    Abstract [en]

    To support the implementation of real-time traffic information systems in the Stockholm city area using automatic vehicle identification (AVI) cameras, a travel time analysis platform has been developed. The system is able of managing and analyzing travel time data stored in a distributed database server where information of camera stations, traffic and weather are integrated. Using Google Map API, users are able to analyze and visualize both online and historical travel time information in an intuitive way. Several existing travel time estimation algorithms are implemented in the system, and are evaluated using four months of AVI data collected in the urban streets and arterials of and near the Stockholm downtown area. The advantages and disadvantages of those algorithms are also analyzed using the highly noisy travel time measurements collected under the urban context. In general, all these algorithms have the potential to be applied for daily travel time estimation. Finally, we point out an essential research question for real-time travel time estimation and suggest a direction that may have the potential to improve the online traffic information quality.

  • 89.
    Ma, Xiaoliang
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301). KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Lei, W.
    Wuhan Univ Technol, Ctr Syst Control & Simulat, Wuhan, Peoples R China..
    Koutsopoulos, Haris N.
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301).
    EVALUATION OF SIGNAL PLANS FOR SUSTAINABLITY USING MICROSCOPIC TRAFFIC IMPACT MODELS2011In: TRANSPORT DYNAMICS / [ed] Szeto, WY Wong, SC Sze, NN, HONG KONG SOC TRANSPORTATION STUDIES LTD , 2011, p. 515-522Conference paper (Refereed)
    Abstract [en]

    The continuous increases of motor vehicles and travel demand in metropolitan areas have brought many challenges to sustainable transport development because of the impacts on energy and environment. This paper presents a simulation-based approach to model and analyze traffic impacts by combining microscopic traffic and instantaneous emissions models. The method is applied for improvement of traffic management measures, concerning not only mobility but also environmental consequences. The study illustrates the essential model calibration procedures that finely tune the CMEM emission model and VISSIM microscopic traffic simulation model using corresponding emission and traffic flow data. The calibrated models have been applied collaboratively in a detailed study on evaluating environmental impacts of two optimal signal control strategies at an isolated intersection in Wuhan.

  • 90.
    Ma, Xiaoliang
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Lei, Wei
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Evaluation of signal plans for sustainability using microscopic traffic impact models2011Conference paper (Refereed)
  • 91. Mishalani, R. G.
    et al.
    Koutsopoulos, Harilaos
    Modeling the spatial behavior of infrastructure condition2002In: Transportation Research Part B: Methodological, ISSN 0191-2615, E-ISSN 1879-2367, Vol. 36, no 2, p. 171-194Article in journal (Refereed)
    Abstract [en]

    A new understanding of the spatial behavior of infrastructure condition is presented and a methodology for identifying this behavior is developed. Based on two deterioration mechanisms, causal and interactive, a nonstationary stochastic spatial model with a piecewise constant mean function is proposed. Based on this model, a methodology founded on nonparametric cluster analysis and dynamic programming is developed to identify the optimal spatial regions, referred to as fields, within which behavior is uniform and, consequently, condition can be estimated accurately. Validation using detailed distress data from three roadway facilities, each 15 km long, is presented. The value of the model is also demonstrated by comparing it against existing methods for characterizing infrastructure condition over space.

  • 92.
    Moran, Carlos
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301).
    Koutsopoulos, Harilaos
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301), Traffic and Logistics (closed 20110301).
    Congestion indicators from the users’ perspective: alternative formulations with stochastic reference level2010Conference paper (Refereed)
    Abstract [en]

    Congestion causes delays and environmental impacts. Policy makers and transport planners have used congestion indicators for monitoring traffic conditions in urban areas. These indicators require defining a reference level of congestion (based for example on free flow conditions). In most cases reported in the literature this reference point is constant and typically corresponds to speed limits. This paper proposes a methodology for the definition of congestion indicators that takes into consideration the preferences and variability across the individual commuters and hence, develops congestion indicators from the users of the system point of view. An analytical approach is developed pointing out that, as expected, for certain simple distributions of desired speed (i.e. triangular) some indicators are biased. A case study using a microscopic simulation model to study a small, dense, and very congested urban network in Stockholm illustrates the impact of applying this new definition in the calculation of congestion indicators. The results of the case study illustrate the bias of existing methods and identify indicators that are less sensitive to the distribution of the reference speed among drivers.

  • 93.
    Mwesige, Godfrey
    et al.
    KTH. Department of Civil and Environmental Engineering, Makerere University Kampala, Uganda.
    Farah, Haneen
    Bagampadde, Umaru
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Effect of passing zone length on operation and safety of two-lane rural highways in Uganda2017In: IATSS RESEARCH, ISSN 0386-1112, Vol. 41, no 1, p. 38-46Article in journal (Refereed)
    Abstract [en]

    This paper presents a methodology to assess the effect of the length of passing zone on the operation and safety of two-lane rural highways based on the probability and the rate of passing maneuvers ending in a no-passing zone. The methodology was applied using observed passing maneuver data collected with tripod-mounted camcorders at passing zones in Uganda. Findings show that the rate at which passing maneuvers end in a no-passing zone increases with traffic volume and unequal distribution of traffic in the two directions, absolute vertical grade, and percent of heavy vehicles in the subject direction. Additionally, the probability of passing maneuvers ending in a no-passing zone reaches 0.50 when the remaining sight distance from the beginning of the passing zone is 245 m for passenger cars or short trucks (2-3 axles), and 300 m for long trucks (4-7 axles) as the passed vehicles. These results suggest policy changes in design and marking of passing zones to enhance safety and operation of two-lane rural highways. (C) 2016 International Association of Traffic and Safety Sciences.

  • 94. Mwesige, Godfrey
    et al.
    Farah, Haneen
    Bagampadde, Umaru
    Koutsopoulos, Haris N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science. Northeastern University, USA.
    A Model and Its Applications for Predicting Passing Rate at Passing Zones on Two-Lane Rural Highways2016In: Journal of transportation engineering, ISSN 0733-947X, E-ISSN 1943-5436, Vol. 142, no 3, article id UNSP 04015049Article in journal (Refereed)
    Abstract [en]

    Passing zones are designed to provide sufficient sight distance for fast vehicles to pass safely slow vehicles and contribute to operational efficiency of two-lane highways. However, lack of suitable models to predict passing rate and capacity has made it difficult to quantify operational benefits of passing zones. In this paper, a model is proposed to predict passing rate in the subject direction at passing zones using traffic and geometric factors. The model is developed based on speed and passing data collected at 19 passing zones in Uganda using pneumatic tube classifiers and video recordings. Findings show that passing rates depend on the length of the passing zone, absolute vertical grade, traffic volume in two travel directions, directional split, 85th percentile speed of free-flow vehicles and percent heavy vehicles in the subject direction. The peak passing rate also referred to as the passing capacity occurs at 200, 220, and 240 vehicles/h in the subject direction for 50/50, 55/45, and 60/40 directional splits, respectively. The model could potentially be applicable in planning, design, and safety evaluation of two-lane rural highways.

  • 95. Mwesige, Godfrey
    et al.
    Farah, Haneen
    Koutsopoulos, Haris N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Risk appraisal of passing zones on two-lane rural highways and policy applications2016In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 90, p. 1-12Article in journal (Refereed)
    Abstract [en]

    Passing on two-lane rural highways is associated with risks of head-on collision resulting from unsafe completion of passing maneuvers in the opposite traffic lane. In this paper, we explore the use of time to-collision (ITC) as a surrogate safety measure of the risk associated with passing maneuvers. Logistic regression models to predict the probability to end the passing maneuver with TTC less than 2 or 3 s-threshold were developed with the time-gap from initiation of the maneuver to arrival of the opposite vehicle (effective accepted gap), and the passing duration as explanatory variables. The data used for model estimation was collected using stationary tripod-mounted camcorders at 19 passing zones in Uganda. Results showed that passing maneuvers completed with TTC less than 3 s are unsafe and often involved sudden speed reduction, flashing headlights, and lateral shift to shoulders. Model sensitivity analysis was conducted for observed passing durations involving passenger cars or short trucks (2-3 axles), and long trucks (4-7 axles) as the passed vehicles for 3 s TTC-threshold. Three risk levels were proposed based on the probability to complete passing maneuvers with TTC less than 3 s for a range of opposite direction traffic volumes. Applications of the results for safety improvements of two-lane rural highways are also discussed. (C) 2016 Elsevier Ltd. All rights reserved.

  • 96.
    Mwesige, Godfrey
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering. Makerere University, Kampala, Uganda.
    Haneen, Farah
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Bagampadde, Umaru
    Makerere University, Kampala, Uganda.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    A model for predicting thepassing rate at passing zones on two-lane rural highways and applicationsManuscript (preprint) (Other academic)
  • 97.
    Mwesige, Godfrey
    et al.
    Makerere University, Kampala, Uganda.
    Haneen, Farah
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Bagampadde, Umaru
    Makerere University, Kampala, Uganda.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Capacity and Safety of Passing Zones on Two-Lane Rural Highways: A Review of Theory and Practice2014In: Journal of Traffic and Logistics Engineering, ISSN 2198-0365, E-ISSN 1602-2297, Vol. 2, no 2Article in journal (Refereed)
    Abstract [en]

    Passing zones are primary operational features of two-lane rural highways where fast vehicles pass slow vehicles using a lane reserved for traffic in opposing direction. The operation of these zones has an effect on the overall safety of two-lane rural highways especially when passing opportunities reduce considerably at higher flows. This paper presents a review on capacity and safety of passing zones on two-lane rural highways. Despite stated importance of passing zones to the operational performance of two-lane rural highways, passing zone capacity has not been estimated and its impact on safety is still not known. Safety evaluations mainly compare adequacy of design and marking passing sight distances to complete passing maneuvers as well as parameters derived from the passing process namely; passing duration, speed difference between passing and passed vehicles, and clearance between passing and opposing vehicle at the end of the maneuver. There is need for further research to address gaps in current capacity and safety evaluation methods of two-lane rural highways with focus on; (a) development of robust passing rate models for individual passing zones based on geometric, environmental and traffic factors, (b) estimation of passing zone capacity, (c) development of criteria to evaluate capacity and safety of passing zones for use by policy makers, planners and transportation engineers and (d) application of passing zone capacity to evaluate rural highway sections with several passing zones.

  • 98.
    Mwesige, Godfrey
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering. Makerere University, Kampala, Uganda.
    Haneen, Farah
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Bagampadde, Umaru
    Makerere University, Kampala, Uganda.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Effect of Passing Zone Length on Operation and Safety of Two-Lane Rural Highways in UgandaManuscript (preprint) (Other academic)
  • 99.
    Mwesige, Godfrey
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering. Makerere University, Kampala, Uganda.
    Haneen, Farah
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Koutsopoulos, Haris
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Risk Appraisal of Passing Zones on Two-Lane Rural Highways and Policy ApplicationsManuscript (preprint) (Other academic)
  • 100. Nissan, A.
    et al.
    Koutsopoulos, Harilaos N.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering. Northeastern University, Boston, United States .
    Evaluation of recommended variable speed limits for motorway traffic control: The case of E4 in Stockholm2009In: 16th ITS World Congress, World Congress on Intelligent Transport Systems (ITS), 2009Conference paper (Refereed)
    Abstract [en]

    Variable Speed Limits (VSL) is a form of motorway control introduced to improve the operations of freeway facilities under congested conditions. This paper evaluates the impact of VSL on the E4 motorway in Stockholm using microsimulation. The test site is heavily congested and includes an integrated Motorway Control System with advisory VSL and Automatic Incident Detection (AID) logic. Experience indicates that the impacts of VSL on traffic condition and safety might be higher if the displayed VSL were mandatory. The objective of the study is to assess the impact of the level of driver compliance to VSL recommended speed, using microsimulation.

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