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This study characterizes lane changing behavior of drivers under differing congestion levels and identifies extreme lane changing traits using high-resolution trajectory data. Total lane change frequency exhibited a reciprocal relationship with congestion level, but the distribution of lane change per vehicle remained unchanged as congestion increased. On average, the speed of trajectories increased by 5.4 ft/s after changing a lane. However, this gain significantly diminished as congestion worsened. Further, the average speed of lane changing vehicles was 3.9 ft/s higher than those that executed no lane changes. Two metrics were employed to identify extreme lane changing behavior: critical time-to-line-crossing (TLCc) and lane changes per unit distance. The lowest 1% TLCc varied between 0.71–1.57 seconds. The highest 1% of lane change rates for all lane changing vehicles was 2.5 lane changes per 1,000 ft traveled. Interestingly, no drivers in thisdataset had both excessive lane changes and lane changes with low TLCc. [ABSTRACT FROM AUTHOR]

ABSTRACT The objective of this research is to evaluate differences in fuel consumption and tailpipe emissions of flexible fuel vehicles (FFVs) operated on ethanol 85 (E85) versus gasoline. Theoretical ratios [...]

This paper explores the use of pedestrian signalization options for crosswalks at one- and two-lane roundabouts to enable these facilities to be accessible to pedestrians with vision impairments. Motivated by uncertainties about the safety of roundabouts for blind pedestrians, audible pedestrian signals hold promise for safely regulating the interaction of vehicles and pedestrians at these facilities. However, the use of pedestrian signals at roundabouts is controversial because of the potential for queue spillback into the circulating lane and delays to vehicular traffic. The objective of this work is to quantify pedestrian-induced delays and queuing impacts of a pedestrian signal placed at the busiest approach of a modern roundabout. The analysis is performed using a calibrated microsimulation model and includes assessment of innovative solutions for crossing geometry and phasing scheme at one-lane and two-lane roundabouts. The results suggest that the impact of pedestrian signals at roundabouts is greatest as vehicle volumes approach capacity, but that vehicle delay and queuing can be mitigated through innovative signal configurations. The findings are important in light of recent discourse concerning the accessibility of roundabouts to pedestrians with vision impairments that may ultimately move towards a requirement for signalization for certain facility types. CE Database subject headings: Intersections; Pedestrians; Traffic signals; Traffic safety.

Following the unprecedented multistate evacuation for Hurricane Floyd in 1999, the North Carolina Department of Transportation and the Department of Crime Control and Public Safety jointly developed a lane reversal plan for Interstate 40 to facilitate evacuation of residents and tourists in southeastern North Carolina. Prior to the 2003 hurricane season, the NCDOT sponsored a two-year research to address areas of operational concern. The first year research findings resulted in modifications to the original lane reversal plan. The second year's findings showed the modified reversal plan to be effective in expediting evacuation from the coastal threat zone. However, modeling of the entire lane reversal plan revealed a potentially extensive queue formation at the contraflow termination point. This paper presents an overview of the project along with the principal research findings and resulting plan modifications. In addition, this paper highlights conclusions and recommendations applicable to the general emergency evacuation problem. DOI: 10.1061/(ASCE)0733-9488(2007)133:1(61) CE Database subject headings: Simulation; Highways; Hurricanes; Evacuation; Traffic management.

ABSTRACT The purpose of this study is to demonstrate a methodology for quantification of high emissions hot spots along roadways based upon real-world, on-road vehicle emissions measurements. An emissions hot [...]

ABSTRACT A study design procedure was developed and demonstrated for the deployment of portable onboard tailpipe emissions measurement systems for selected highway vehicles fueled by gasoline and E85 (a blend [...]

A critical element in assessing traffic performance at the individual lane level at signalized intersections is the knowledge of traffic volumes in each lane. Typically, turning movement volumes are available only for the entire approach, not for each individual lane. Collecting turning movement volumes by lane is costly and, for future year analyses, is unattainable. This paper summarizes the results of an empirical study of lane volume data that were collected at three intersections and provides an evaluation of six lane selection strategies used to estimate lane flows. The lane selection strategies are used as part of the subgroup approach for estimating saturation flow. This limited evaluation indicates that a lane selection strategy based on equal back of queue or cycle-average queue provides the best prediction of individual lane volumes in the field. This result is intriguing, given that at least three international capacity guides currently use an equal flow ratio or degree of saturation strategy for estimating lane flow and indicates a need for a larger data collection effort to confirm the results of this study. CE Database keywords: Intersections; Traffic signals; Traffic characteristics; Traffic flow; Evaluation.

Traffic signal warrants documented in the Manual on Uniform Traffic Control Devices neglects the effect of daily and hourly volume variations in traffic. Furthermore, current practice cannot be used to prioritize signal installations among multiple intersections that meet the warrants. Finally, there is no guidance in the Manual on Uniform Traffic Control Devices on how the warrants can be applied to projected traffic conditions when hourly counts are not available. This paper describes a probabilistic approach to implementing traffic signal warrants. The proposed approach used Monte Carlo simulation to generate, on the basis of variable hourly traffic counts, the probability that any particular signal warrant will be met at an intersection. The simulation approach was extended to develop planning level guidelines for signal installation using predefined synthetic traffic flow profiles and the average daily traffic estimates for the intersecting streets. The proposed guidelines were compared with current planning guidelines used in Texas and California. The comparison results indicate that the Texas guidelines tend to underestimate the need for traffic signal installation, whereas the California guidelines tend to overestimate the need.

Real-time traffic data are the lifeline sustaining the operation of Advanced Traffic Management and Advanced Traveler Information Systems (ATMS/ATIS). Data are essential to drive algorithms related to congestion/incident detection, travel time forecasting, and real-time route guidance. A common problem in many ATMS/ATIS applications is the sparsity of real-time traffic data, reflecting the financial constraints of acquiring and maintaining large-scale traffic monitoring systems. This paper proposes the use of intelligent processing, or data integration tools, to overcome the data sparsity problem and make the best use of existing data resources. This approach recognizes the elements of uncertainty and vagueness in defining and solving the problem. An example application of the proposed data integration method is presented in the context of a congestion detection algorithm. The method uses an imprecise knowledge representation within the framework of fuzzy operator logic (FOL) and the modified Dempster-Shafer rule of combination. Results indicate that knowledge of a link congestion status (i.e., congested or uncongested) increased several folds after the data integration algorithm was applied. Further work is needed to calibrate the algorithm in the field (in this study simulation was used) and to apply the procedures on large-scale networks.

This paper investigates the reliability of TRANSYT-7F optimal solutions from two perspectives: (1) the effect of the selected optimization criterion on the values of various system performance measures; and (2) the extent to which TRANSYT-7F signal plans remain optimal when evaluated in a microscopic and stochastic traffic environment. The well-established CORSIM model was used for the latter test. A customized code has been developed that can automatically generate statistical distributions of selected performance measures in CORSIM based on various TRANSYT-7F optimization runs. The method has been applied to a calibrated test network in Chicago consisting of 9 signalized intersections with 50 nodes and 74 links. It was found that while good correlation existed between the corresponding performance measures in TRANSYT-7F and CORSIM under light traffic, their correlation diminished under congested flow. In particular, the best signal strategy identified in TRANSYT-7F was not the best in the CORSIM environment. The discrepancies are undoubtedly due to the basic difference between the two models: TRANSYT-7F is deterministic, CORSIM is stochastic.