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The representative path set between an origin and destination (OD) pair is useful for various transportation areas such as traffic assignment, travel information service, and traffic management. With the development of telecommunication technology, a car navigation system now collects trajectory-type data that can show the routes generated by drivers. Thus, the travel paths of individual travelers are available for the transportation study. Unfortunately, the availability of individual path data cannot guarantee direct application to the transportation model because it does not give us the significant path set between the OD pairs. Every driver in the real world has different starting and finishing points, yet these points are in a same origin and destination zone. In this study, a new methodology to determine the representative path set between an OD pair based on vehicle trajectory data is developed. This new model is tested with simulation data and compares various results according to clustering parameters. Experimental results indicate that the developed model correctly clustered representative paths, and these could represent subtrajectories from various trajectory data. [ABSTRACT FROM AUTHOR]

Lane changing has received much attention as it is a significant component of microscopic traffic simulation. Many studies have focused on the details of the lane changing maneuver from external observation-based data which do not consider the type of driver performing the maneuver. The research reported in this paper relates the physical details of freeway lane changing to the type of driver performing the maneuver. Forty-six research participants drove an instrumented vehicle and performed a combined total of 726 freeway lane changes. Each research participant was categorized into one of four groups ranging from conservative to aggressive based on cluster analysis. The data were analyzed to identify any trends between the different driver types and their lane changing characteristics, specifically lane changing duration and gap acceptance characteristics. In general, more conservative drivers have greater lane changing durations than aggressive drivers. The gap acceptance comparison among driver types did not yield any conclusive trend. In addition, distributions were fitted to lane changing duration and gap acceptance histograms. The results suggest that driver type impacts freeway lane changing behavior, and therefore should be taken into account when developing or refining simulation-based lane changing models. [ABSTRACT FROM AUTHOR]

This paper presents a departure time choice analysis, based on the notion of a latent carpooling preference. The study is based on combined revealed preference and stated preference survey data collected on the Maryland side of the Capital Beltway (I-495). A conditional logit model is estimated to identify drivers' choice when tolls and congestion management strategies, including high-occupancy vehicle (HOV) lanes and high-occupancy toll (HOT) lanes, are implemented. Then a latent class model accounting for heterogeneity across groups of drivers is proposed and estimated to examine the difference in behavioral preferences across groups. The latent class model reveals significant heterogeneity in drivers' latent preference toward ride-sharing, which can potentially support ranges of transportation policy and incentive design related to congestion management strategies such as HOV/HOT lane usage. [ABSTRACT FROM AUTHOR]

This paper presents the analysis of traffic operations at 34 instances of yellow/red malfunction flash and nine instances of red/red malfunction flash in the Atlanta area. Malfunction flash occurs when a traffic signal's malfunction monitoring unit detects a problem and automatically initiates a flashing operation. Many of these instances were during periods of high demand, and a high level of driver confusion was documented. The stopping rate of major-street through drivers (i.e., those facing a flashing yellow signal and not required to stop) exceeded 75% at some yellow/red flash intersections. This eliminates many of the operational benefits that yellow/red flash is generally assumed to have over red/red flash and may create a safety hazard. To predict major-street (flashing yellow) stopping rates, logit models were developed. At red/red flash intersections, 10-20% of drivers did not stop before entering the intersection; many of these drivers crept through or 'piggybacked' with another vehicle. [ABSTRACT FROM AUTHOR]

Despite the potential effectiveness of the dynamic late merge (DLM) control, most existing DLM systems, based on static thresholds, cannot best perform under time-varying traffic conditions. This paper presents an advanced dynamic merge control, called a lane-based dynamic merge control model and its operational algorithm, which is based on the optimized control thresholds that take into account the interactions among the speed, flow, and available work zone capacity. The focus of this study is on how to select the control variables and to determine their optimal thresholds in response to traffic flow dynamics. Evaluation results with extensive simulation experiments have shown the promising properties of the proposed dynamic merge control and its operational algorithm. [ABSTRACT FROM AUTHOR]

There is an absence of nationally accepted warrants for left-turn phasing at signalized intersections. Some guidelines recommend a protected left-turn phasing for turns with three or more opposing through lanes. However, there is no research that justifies this recommendation. A Web-based motorist survey was conducted to find how motorists perceive difficulty and their preference for protected left-turn signalization vis-à-vis the number of opposing lanes. The ordered probit modeling of 2,017 responses suggests that driver perception of difficulty to make turns without protected left-turn signals increases with intersection size. As high as 91% of the respondents stated that they much or extremely prefer a protected left-turn signal at an intersection where left-turn vehicles have to cross three lanes of opposing through traffic. The ordered probit models also provide indications of the effects of various sociological variables on the probabilities of driver perceptions of difficulty and preference. The estimated models provide a sensitive tool for making decisions about the left turn treatment at signalized intersections. [ABSTRACT FROM AUTHOR]

In this paper a comprehensive microscopic model of driver behavior in uninterrupted traffic flow is developed. The model aims to explain or predict the actions of a driver in a variety of driving scenarios ranging from free flow conditions on wide roads to forced flow conditions on narrow two-way roads. The salient features of the proposed theory are (1) a single model (or framework) is used to describe driver behavior in different driving scenarios and (2) the response of drivers through both steering control and speed control are modeled. Driver behavior is simulated in 19 different driving scenarios. Results from these simulations show the efficacy of the proposed model in explaining/predicting driver behavior. [ABSTRACT FROM AUTHOR]

The perception of the driver of the road features ahead is an important human factor that can considerably affect traffic safety and design consistency, and should be addressed in road design. An erroneous perception of the road can lead to actions that may compromise traffic safety. Previous studies have shown that combined horizontal and vertical alignments can cause a wrong perception of the horizontal curvature. In this paper, the hypothesis that the perception of the driver of the horizontal curvature is affected by the overlapping vertical alignment is examined analytically. Computer animation was selected as a three-dimensional presentation method of the road perspective, and was found to produce a realistic view of the road. A sample of drivers was interviewed to determine the radius of a horizontal curve on a level grade that would look equal to a radius of a horizontal curve overlapping with a vertical curve. The statistical analysis showed that the horizontal curvature looked consistently sharper when it overlapped with a crest curve and consistently flatter when it overlaps with a sag curve. Field measurements of operating speed profiles on a selected sample of combined alignments confirmed that, for the selected sample of alignments, driver behavior on horizontal curves depended on the overlapping vertical curve rather than the vertical grade of the approach tangent. [ABSTRACT FROM AUTHOR]

Many studies conducted over the last 20 years show that speed bumps have only a limited affect in decreasing traffic speed, especially compared to better designed passive speed control devices, such as speed humps or cushions. These findings were confirmed during an investigation described in the present study conducted in an Italian town. Besides the well known phenomena, such as sudden slow down and acceleration before and after the bump (which is often a source of accidents), it was observed that drivers tend to perform all sorts of maneuvers to reduce their discomfort as much as possible when approaching the undulation. This fact is particularly evident on streets where the speed bumps do not extend over the entire street. This kind of misplacement seems to encourage drivers to perform avoidance maneuvers, such as short deviations into the opposite lanes or parking lanes and bus stops. This study is an attempt to reach a qualitative and quantitative classification of possible alterations in drivers’ behavior due to the presence of the speed bumps. The result of more than 25,000 observations of cars and motorcycles reveal that speed bumps, where not properly installed, induce many drivers (up to 50% for cars and up to 85% for motorcyclists) to avoid the undulation to reduce the level of noise and vibrations perceived inside/on the vehicle. [ABSTRACT FROM AUTHOR]

This paper presents a methodology for critical gap analysis at signalized intersections with unprotected opposing left-turn movements. Highway capacity manual (HCM) methodology for estimating potential capacity uses base critical gap and base follow-up time, which are adjusted to reflect specific conditions of each intersection. That methodology assumes an unobstructed line-of-sight for drivers while executing left-turn maneuvers. However, the line-of-sight is not always unimpeded. Previous studies have shown that leading noncompact (larger and taller) vehicles and vehicles in the opposing left-turn lane may impede the line-of-sight. Specifically, the studies have demonstrated that the impedance may result in a capacity reduction. In order to quantify the capacity reduction, we present a methodology to modify the HCM critical gap and follow-up time model when the line-of-sight of unprotected left turn maneuver is obstructed. We introduce new adjustment factors to account for vehicles in the opposing left-turn lane obstructing the line-of-sight during the left-turn maneuver. Using field data from Baltimore and Annapolis, Maryland, we show that the obstruction increases the left-turn critical gap and the left-turn follow-up time, and hence decreases the potential capacity for left turns at intersections with unprotected left-turn movements. This capacity reduction may be a significant contributor to systemwide delay during rush hour, and may influence dilemma zone and red light running behavior, which are subjects of future research. [ABSTRACT FROM AUTHOR]