Vehicle Arrival Time Research Articles

Constructing a bivariate distribution for freeway speed and headway data

Accurate description of speed and headway distributions is critical for developing microscopic traffic simulation models. A number of microscopic simulation models generate vehicle speeds and vehicle arrival times as independent inputs to the simulation process. However, this traditional approach ignores the possible correlation between speed and headway. This article proposes a Farlie–Gumbel–Morgenstern (FGM) approach to construct a bivariate distribution to simultaneously describe the characteristics of speed and headway. For the FGM approach, the distributions of speed and headway need to be specified separately before the construction of the bivariate distribution. While using conventional distributions for headway, this study uses normal, skew-normal and skew-t mixture distributions for speed. To examine the applicability of the FGM, the proposed approach is applied to a 24-hour speed and headway dataset collected on IH-35 in Austin, Texas. The results show the FGM approach has successfully constructed the bivariate distribution for speed and headway. Moreover, data analyses indicate that there is a weak correlation coefficient between speed and headway. The methodology in this research can be used in analysing the characteristics of speed and headway data. The findings can also be used in the development and validation of microscopic simulation models for freeway traffic.

Dynamic yard crane dispatching in container terminals with predicted vehicle arrival information

The performance of a container terminal depends on many aspects of operations. This paper focuses on the optimal sequencing of a yard crane (or YC for short) for serving a fleet of vehicles for delivery and pickup jobs. The objective is to minimize the average vehicle waiting time. While heuristic algorithms could not guarantee an optimal solution, a conventional mathematical formulation such as mixed integer program would require too much computing time. We present two new algorithms to efficiently compute YC dispatching sequences that are provably optimal within the planning window. The first algorithm is based on the well-known A ∗ search along with an admissible heuristics. We also incorporate this heuristics into a second backtracking algorithm which uses a prioritized search order to accelerate the computation. Experimental results show that both new algorithms perform very well for realistic YC jobs. Specifically, both are able to find within seconds optimal solutions for heavy workload scenarios with over 2.4 × 10 18 possible dispatching sequences. Moreover, even when the vehicle arrival times are not accurately forecasted, the new algorithms are still robust enough to produce optimal or near-optimal sequences, and they consistently outperform all the other algorithms evaluated.

Analysis of Peer Data on Intersections for Decisions about Coordination of Arterial Traffic Signal

Decisions on whether to coordinate adjacent intersections are currently made by rules of thumb and couple indices that are based on ratios of volume to distance with modeled traffic flows. As high-resolution event data from signalized intersections become more readily available, it becomes possible to analyze actual link vehicle flows to better characterize whether (and when) signal coordination is desirable. This paper proposes and demonstrates a methodology that uses peer data obtained from adjacent intersections to assess opportunities to improve arterial progression if a noncoordinated system is coordinated. The beginning of green from the upstream intersection was combined with vehicle arrival times from a downstream intersection to characterize whether vehicles were likely to arrive in consistent platoons at the downstream signal. The peer data–based methodology was used to investigate the benefits of extending a coordination plan to a system running without coordination during a late-night period. A case study of a fully actuated late-evening timing plan on an arterial identified opportunities for potential benefits from coordination; the implementation of a timing plan for an adjacent time period reduced travel times by approximately 1 min in both directions on the arterial.

Global Positioning System Integrated with Personalized Real-Time Transit Information from Automatic Vehicle Location

Navigation of a transit system can be a major obstacle to new riders, especially special-needs populations and tourists. For those with cognitive disabilities (approximately 14.3 million Americans, or 6% of the population), it is challenging to plan and execute a trip without assistance. A travel assistance device (TAD) software prototype for Global Positioning System–enabled phones was developed to aid new transit riders, especially those who are cognitively disabled. When riders approach their stops, the TAD vibrates and delivers audio and visual messages to the riders to request a stop and exit the vehicle. This paper reports the results of a study that integrated communication with an automatic vehicle location (AVL) system on transit vehicles into TAD, with new features, including personalized notices of estimated vehicle arrival time and of vehicle arrival. Implementation issues addressed include the limitations of accessing AVL data for real-time consumer use, integration of different transit agency data sources, and consideration of the effects of software applications (e.g., wireless data communication) on mobile phone functionality (e.g., battery life).

Prediction of Transit Vehicle Arrival Time for Signal Priority Control: Algorithm and Performance

We develop an algorithm for predicting the arrival times of a transit vehicle at signalized intersections, with a focus on meeting the accuracy requirement associated with signal priority control applications. The algorithm uses both historical and real-time Global positioning system (GPS) vehicle location data. There are no data from other detectors, such as loops or cameras. The arrival time prediction is formulated as an optimal <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">posteriori</i> parameter estimation problem, where the model is consisted of a historical model and an adaptive model that adaptively adjusts its filter gain based on real-time data. The estimates generated by these two models are fused in a weighted average derived from the solution of the parameter estimation problem. The prediction algorithm adaptively adjusts its weight distribution using error variances obtained from the two models. We include some simulations of field test results and their statistics to demonstrate the performance and convergence of the solution.

A supply-demand model for communication of transit signal priority requests

A critical issue encountered in implementing a transit signal priority system is to ensure that communication between transit vehicles and the traffic centre can be established for transmitting signal priority requests and vehicle arrival time information needed for executing signal priority control at signal-controlled intersections. The available communication channel bandwidth, however, is not guaranteed to meet the demand from a potentially large number of transit vehicles requesting signal priority service. In this paper, we define and analyse this supply-demand problem with simulations of a simple time model. The emphasis is to investigate the logistic issues and identify the critical parameters, so that this simple model might serve as a framework for constructing a more complex realistic model upon which an efficient scheduling protocol could be designed to meet signal priority service demand.

A cluster-based optimization approach for the multi-depot heterogeneous fleet vehicle routing problem with time windows

This paper presents a novel three-phase heuristic/algorithmic approach for the multi-depot routing problem with time windows and heterogeneous vehicles. It has been derived from embedding a heuristic-based clustering algorithm within a VRPTW optimization framework. To this purpose, a rigorous MILP mathematical model for the VRPTW problem is first introduced. Likewise other optimization approaches, the new formulation can efficiently solve case studies involving at most 25 nodes to optimality. To overcome this limitation, a preprocessing stage clustering nodes together is initially performed to yield a more compact cluster-based MILP problem formulation. In this way, a hierarchical hybrid procedure involving one heuristic and two algorithmic phases was developed. Phase I aims to identifying a set of cost-effective feasible clusters while Phase II assigns clusters to vehicles and sequences them on each tour by using the cluster-based MILP formulation. Ordering nodes within clusters and scheduling vehicle arrival times at customer locations for each tour through solving a small MILP model is finally performed at Phase III. Numerous benchmark problems featuring different sizes, clustered/random customer locations and time window distributions have been solved at acceptable CPU times.

Traffic control in transportation systems

PurposeThis paper deals with real‐time control of urban traffic with an emphasis on public transportation systems. The main objective is the regulation of traffic after the occurrence of disturbances. In a few words, the problem is to find a feasible schedule for some vehicles of some lines subject to certain constraints in order to design a decision support system (DSS) that detects, analyses and resolves disturbances.Design/methodology/approachThis work is achieved in cooperation with a public transport company called SEMURVAL. It consists of developing a DSS for the future transportation network of Valenciennes (city in the north of France). As a consequence, regulators of traffic have to treat a new lot of information and it becomes necessary to assist them in order to keep up with demands and to come up to passengers' expectations and hopes.FindingsFrom the case study finds that the solution proposed assures that arrival times of vehicles are more regular.Originality/valueThe solution proposed presents a good combination of scheduling decisions permitting the good regulation of traffic.

Empirical Analysis of Traffic Sensor Data Surrounding a Bottleneck on a German Autobahn

The evolution of traffic from freely flowing to queued conditions and from queued to freely flowing conditions was studied along a 14-km section of German Autobahn 9 near Munich. Several bottlenecks were identified by a systematic examination of the excess vehicle accumulation and excess travel time (delay) that arose between measurement locations. It is shown that a bottleneck arose repeatedly downstream of an on-ramp on a busy freeway. The analysis tools used were curves of cumulative vehicle arrival number versus time and curves of cumulative time-averaged velocity versus time. The data required to construct these curves were available in archived form from inductive loop detectors embedded in the freeway. These cumulative plots were carefully and systematically transformed to produce the resolution necessary to reveal important details of the evolution of traffic flow features. These high-resolution transformed curves have made it possible to identify key time-dependent features related to the activation and deactivation of the bottleneck.

Part 2: Queuing and Lane-Changing Behavior: Empirical Analysis of Traffic Sensor Data Surrounding a Bottleneck on a German Autobahn

The evolution of traffic from freely flowing to queued conditions and from queued to freely flowing conditions was studied along a 14-km section of German Autobahn 9 near Munich. Several bottlenecks were identified by a systematic examination of the excess vehicle accumulation and excess travel time (delay) that arose between measurement locations. It is shown that a bottleneck arose repeatedly downstream of an on-ramp on a busy freeway. The analysis tools used were curves of cumulative vehicle arrival number versus time and curves of cumulative time-averaged velocity versus time. The data required to construct these curves were available in archived form from inductive loop detectors embedded in the freeway. These cumulative plots were carefully and systematically transformed to produce the resolution necessary to reveal important details of the evolution of traffic flow features. These high-resolution transformed curves have made it possible to identify key time-dependent features related to the activation and deactivation of the bottleneck.

Development of a System for Collecting Loop-Detector Event Data for Individual Vehicles

Typical freeway inductive loop detection systems, under normal operation, aggregate individual loop-detector actuations sampled at 60 Hz into 20-s or 30-s averages of velocity, flow, and lane-occupancy measurements. While such aggregations are appropriate for serving as inputs to control system algorithms, and they save disk space for archiving loop data, a large amount of useful data regarding individual vehicles is lost. For single-loop detectors, the lost information includes individual vehicle arrival, departure, and presence times. For speed traps, the lost information also includes the calculated individual vehicle speed and length. Yet this information about individual vehicles is desirable to transportation researchers and planners. The unavailability of this information makes in-depth investigation of detector errors difficult or even impossible. A system for collecting detector event data is proposed. This system can sample loop actuations with sampling rates of 60 Hz or higher and then save, process, and present the collected event data in real time without interfering with the detector controller’s normal operation. A stand-alone Windows program was developed for performing real-time high-frequency loop event data collection. A system reliability test and field application indicate that the system can collect realtime detector event data at a high sampling rate (60 Hz or higher). Additionally, this system makes real-time loop data quality evaluation, loop malfunction identification, and loop error correction feasible.

Some observed queue discharge features at a freeway bottleneck downstream of a merge

Details of traffic evolution were studied upstream and downstream of a freeway bottleneck located near a busy on-ramp. It is shown that on certain days the bottleneck became active upon dissipation of a queue emanating from somewhere further downstream. On such occasions, the bottleneck occurred at a fixed location, approximately one kilometer downstream of the merge. Notably, even after the dissipation of a downstream queue, the discharge flows in the active bottleneck were nearly constant, since the cumulative counts never deviated much from a linear trend. The average bottleneck discharge flows were also reproducible from day to day. The diagnostic tools used in this study were curves of cumulative vehicle arrival number versus time and cumulative occupancy versus time constructed from data measured at neighboring freeway loop detectors. Once suitably transformed, these cumulative curves provided the measurement resolution necessary to observe the transitions between freely flowing and queued conditions and to identify some important traffic features.

Intermodal Transit System Coordination

In urban areas where transit demand is widely spread, passengers may be served by an intermodal transit system, consisting of a rail transit line (or a bus rapid transit route) and a number of feeder routes connecting at different transfer stations. In such a system, passengers may need one or more transfers to complete their journey. Therefore, scheduling vehicles operating in the system with special attention to reduce transfer time can contribute significantly to service quality improvements. Schedule synchronization may significantly reduce transfer delays at transfer stations where various routes interconnect. Since vehicle arrivals are stochastic, slack time allowances in vehicle schedules may be desirable to reduce the probability of missed connections. An objective total cost function, including supplier and user costs, is formulated for optimizing the coordination of a general intermodal transit network. A four-stage procedure is developed for determining the optimal coordination status among routes at every transfer station. Considering stochastic feeder vehicle arrivals at transfer stations, the slack times of coordinated routes are optimized, by balancing the savings from transfer delays and additional cost from slack delays and operating costs. The model thus developed is used to optimize the coordination of an intermodal transit network, while the impact of a range of factors on coordination (e.g., demand, standard deviation of vehicle arrival times, etc) is examined.

Dynamic Vehicle Dispatching at the Intermodal Transfer Station

Transfer time is one of the most important service quality indicators for evaluating intermodal transit systems. In the advent of advanced public transportation systems, vehicle arrival times and transfer demand can be obtained in real time. Thus, the decision of dispatching vehicles at transfer stations can be optimized to reduce the transfer cost. A time-varying total-cost function, including connection delay and missed-connection costs incurred by transfer passengers and vehicle holding cost, is formulated as a function of holding times for vehicles that are ready to be dispatched at transfer stations. A procedure is developed to dynamically optimize the dispatching time for each ready vehicle by minimizing the time-varying objective function. A transit network consisting of four routes connecting at a transfer terminal is designed in this study to demonstrate the application of the dispatching model. The proposed method can be used to advance transit vehicle dispatching strategies and reduce the transfer time.

Transit Vehicle Arrival Prediction: Algorithm and Large-Scale Implementation

An algorithm is presented to predict transit vehicle arrival times up to 1 h in advance. It uses the time series of data from an automated vehicle location system, consisting of time and location pairs. These data are used with historical statistics in an optimal filtering framework to predict future arrivals. The algorithm is implemented for a large transit fleet in Seattle, Washington, and the prediction results for hundreds of locations are made widely available on the Web. An evaluation of the second busiest but most complex prediction site is presented to demonstrate the value of prediction over the use of schedules alone.

Some traffic features at freeway bottlenecks

Observations from two freeway bottlenecks in and near Toronto, Canada indicate that the average rate vehicles discharge from a queue can be 10% lower than the flow measured prior to the queue's formation. Absent any influences from downstream, the queue discharge flows exhibited nearly stationary patterns that alternated between higher and lower rates. These alternating flow patterns were especially evident at one of the two sites, although the feature occurred at both sites during periods that immediately followed the onset of upstream queueing; i.e. a queue's formation was always accompanied by a relatively low discharge rate followed later by a temporary surge in the discharge flow. When plotted cumulatively over time, however, the counts of discharging vehicles generally did not deviate by more than about 50 vehicles from a trend line of constant slope. Thus, the discharge flows are described as being `nearly' constant; i.e. they varied (slightly) about a fixed rate. At each site, this average discharge rate exhibited little deviation from day to day. The present findings came by visually comparing transformed curves of cumulative vehicle arrival number vs time and cumulative occupancy vs time measured at neighboring loop detectors. This treatment of the data provided clear presentations of some important traffic features and this facilitated a detailed study of bottleneck flows.

Driver memory: Motorist selection and retention of individualized headways in highway traffic

The paper presents evidence that (1) drivers have different personalities in that they follow vehicles at different headways, and (2) drivers retain their personalities in that each driver tends to maintain his headway over space and, in some instances, drivers return to their headways after being forced by a traffic disturbance to alter them temporarily. This attribute, which we term driver memory, is revealed by visual inspection of modified curves of measured cumulative vehicle arrival number versus time.

Operational Benefits of Electronic Toll Collection: Case Study

This paper reports the improvements in traffic operations at the electronic toll collection plazas of the Orlando-Orange County Expressway Authority. Service time, vehicle arrival times, and departure times, as well as vehicle counts were collected “before” and “after” the installation of automatic vehicle identification technology known as E-PASS. The findings indicate that, for the dedicated E-PASS lane, the measured capacity has tripled, the service time has decreased by five seconds per vehicle, the average queuing delay has decreased by one minute per vehicle, the maximum queuing delay has decreased by 2.5–3 minutes per vehicle, and the total queuing delay has decreased by 8.5–9.5 vehicle-hours per morning peak hour for that lane. Also, variability in the headway has been reduced significantly in the dedicated E-PASS lane. Capacity, headway, and service times of the mixed (manual/E-PASS or automatic/E-PASS) lanes did not change significantly. However, arrivals have shifted to the dedicated E-PASS lan...

Perception of Oncoming Vehicle Time-to-Arrival

An experiment was conducted in a fixed-base driving simulator which manipulated the time-to-arrival (Ta) of an oncoming vehicle, the viewing distance to that vehicle and the type of oncoming vehicle to determine the perceptual basis for a left-turn decision. Forty-eight participants were randomly assigned to a group where either a motorcycle, a compact car, a full-size car, or delivery truck represented the oncoming vehicle. There were an equal number of participants of each gender in the four groups. As Ta was increased, underestimation of vehicle arrival time also increased. Significant main effects were found for Ta, gender of participants, vehicle type, and viewing distance, and for interactions for gender x Ta and gender x vehicle type. Males and females differed in their accuracy of judgments for vehicle types, where males were more accurate in estimating the arrival of delivery vans and motorcycles than their female peers. The pattern of results for the size of the approach vehicle were consistent with a margin-of-safety explanation which argues that driver underestimation of the arrival times of larger vehicles generally allows larger margins-of-safety than for smaller vehicles. The importance of these findings for the development of advanced in-vehicle collision avoidance and warning systems is briefly considered.

Traffic Conflicts in Expressway Merging

The risk of collision in an expressway merging process is investigated using the traffic conflict technique. The severity of conflict in a merging event is quantified by a measure that is the inverse of the time measured to collision. To determine this measure, recordings of merging events were obtained at a merging area of an expressway in Singapore over eight periods, and the arrival times of vehicles at constantly spaced intervals were subsequently extracted in the laboratory. The errors in the data‐collection process were minimized by using two video cameras simultaneously in the recording process to increase the size of images and playing back the tapes at a lower speed during data extraction. The systematic errors in the data due to observers' bias were also estimated to facilitate data adjustment. Based on the adjusted data, the computed measure from about 200 merging events in each observation period was found to be best fitted by the mixed Weibull distribution. Using the tail end of the distribution, the probability of near‐accident per merge in each period was estimated.