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Highlights • The mobility levels of TWSC, RAB, and SIG are estimated and compared. • Impacts of turning traffic & pedestrian demand on intersection delay are considered. • Selection charts for appropriate control strategy at intersections are developed. • Turning traffic at the major & minor streets affect intersections' performance. • Pedestrians negatively affect the performance of TWSC and RAB. Abstract The selection of proper control types at intersections at the planning stage is an important concern considering the difficulty in comparing the performance of different control types. Therefore, several manuals proposed selection charts to guide traffic engineers in identifying the control strategy that yields to the lowest delay and the highest level of service. However, most of these methodologies consider only total major and minor street traffic flows. They do not necessarily suggest to investigate the impact of turning traffic and pedestrian flows, which limits the applicability of their recommendations. Thus, this study aims to propose a procedure to assess the selection of the optimum control strategies among two-way stop, roundabout and signalization using average intersection vehicle delay as the evaluation criterion. The impact of turning traffic on the major and minor streets as well as the impact of pedestrians are integrated into the developed analytical methodology for the estimation of average intersection vehicle delay. A typical layout of isolated four-leg two-way intersection is assumed for the model development. It is concluded that turning traffic and pedestrians play essential roles in the performance of intersections. As pedestrian flow increases, signal control becomes prevailing over the other control types. [ABSTRACT FROM AUTHOR]

The article offers information on the smart right-turn designs at traffic intersections in the U.S. and their impact on traffic safety, discussing the consideration of traffic crashes while building the design; and the use of Empirical Bayes method to assess the effectiveness of smart right-turns.

Introduction Understanding driver behavior is important for traffic safety and operation, especially at intersections where different traffic movements conflict. While most driver-behavior studies are based on simulation, this paper documents the analysis of driver-behavior at signalized intersections with the SHRP 2 Naturalistic Driving Study (NDS) data. This study analyzes the different influencing factors on the operation (speed control) and observation of right-turn drivers. Method A total of 300 NDS trips at six signalized intersections were used, including the NDS time-series sensor data, the forward videos and driver face videos. Different factors of drivers, vehicles, roads and environments were studied for their influence on driver behavior. An influencing index function was developed and the index was calculated for each influencing factor to quantitatively describe its influencing level. The influencing index was applied to prioritize the factors, which facilitates development and selection of safety countermeasures to improve intersection safety. Drivers' speed control was analyzed under different conditions with consideration of the prioritized influencing factors. Results Vehicle type, traffic signal status, conflicting traffic, conflicting pedestrian and driver age group were identified as the five major influencing factors on driver observation. Conclusions This research revealed that drivers have high acceleration and low observation frequency under Right-Turn-On-Red (RTOR), which constituted potential danger for other roadway users, especially for pedestrians. Practical applications As speed has a direct influence on crash rates and severities, the revealed speed patterns of the different situations also benefit selection of safety countermeasures at signalized intersections. [ABSTRACT FROM AUTHOR]

The article offers information on the two requirements that may reduce the operational efficiency of the intersection which include adding more lanes and a longer signal phasing clearance time.

Behavior of right turning vehicles in the context of safety is characterized by their use of turning indicators and compliance with the stop rule. They are influence by the width of the carriageway and the variation in volume on the major road with respect to the traffic moving in the near and far side direction. Other factors affecting the behavior are the speed and spacing between vehicles moving on the major road. Lack of adequate past knowledge on the effect of geometric variation in terms of road width and directional variation in volume on the safety of unsignalized intersections have provided the motivation for this study. This paper focuses on the many factors that affect the behavior of right-turning vehicles resulting into conflicts. A brief account of the unique indigenous maneuver termed as the “Weaving Merging Right Turn” (WMRT) is provided and its effectiveness with respect to conventional right turn is evaluated. Data of 39,016 vehicles collected on 10 sites between January and June 2014 was analyzed. Multiple accidents were observed only on sites which had near side traffic volume greater than far side traffic volume. This result remains consistent with sites having single as well as multiple lanes per direction on the major roads. The number of conflicts for vehicles performing the WMRT was 2.5 times less as compared to the conventional right turn. Moreover WMRT was found to be the maneuver of choice for right turning motorcyclists with 60% of them opting for it over the conventional right turn on intersections having major road width less than 9 m. None of the motorcyclists, which were involved in a traffic conflict, were observed to use their turning indicator. Moreover none of the motorcyclists, which experienced a traffic conflict, were found to comply with the stopping rule at sites with major road width less than 9 m. On sites with major road width greater than 9 m, 45% of motorcyclists, involved in a traffic conflict, complied with the stopping rule as compared to 79% by vehicles other than motorcycles. [ABSTRACT FROM AUTHOR]

A simulation based on VISSIM and its external driver model dynamic link library (DLL) was used to investigate the efficiency and safety of a two-way left-turn lane (TWLTL) on roads with staggered intersections (SIs). The impacts of traffic volume, ratio of left-turn vehicles, and stagger distance on SIs and conventional cross intersection (CI) were simulated with the following results: (1) SIs with stagger distance shorter than 200 m show few advantages in terms of average delay over a CI irrespective of traffic volume and left-turn ratio; (2) In contrast, SIs with stagger distance longer than 200 m show advantages that, however, disappear with an increase in traffic volume and left-turn ratio; and (3) SIs show a significantly higher number of traffic conflicts than CIs, indicating that they have more serious safety problems. These results should help traffic researchers and practitioners decide whether it is feasible to establish SIs on existing roadways with TWLTLs and the appropriate stagger distance for SIs, as well as whether it is appropriate to change a road that has dense SIs into a TWLTL cross section. [ABSTRACT FROM AUTHOR]

The article discusses a study on the safety and mobility characteristics associated with the lane-changing (LC) behavior of drivers at bus stops on three-lane roadways in the U.S. Topics covered include the parameters used to consider the probability of LC violation including the left-turn lane type, the bicycle lane presence, and the opposing traffic volume, and the recommendations for reducing the number of LC violations.

The simulation of U-turns is currently of great interest to many transportation professionals due to the widespread use of indirect driveway left-turn treatments. In this study, a procedure was proposed to help transportation professionals model U-turn movements at unsignalized intersections with nontraversable median cross sections in the traffic simulation program VISSIM. The behavioral features of U-turning drivers, such as the priority rule, lane selection, and turning speed of U-turns, were determined using data collected from 13 different locations. A procedure based on a genetic algorithm was proposed to calibrate and validate the VISSIM simulation model. The simulation results of the calibrated VISSIM model were compared to field measured capacity and to the capacity estimated using gap acceptance models developed in previous studies. The calibrated VISSIM simulation model yields mean absolute percent errors of 17.6 and 20.7% for four-lane and six-lane streets, respectively. The results show that VISSIM provides reasonable capacity estimates for U-turns at unsignalized intersections with raised median cross sections, after crucial parameters are properly defined and calibrated. [ABSTRACT FROM AUTHOR]

Vehicle turning maneuver is a major design control in roadway alignment, pavement and the placement of curbs at highway intersections. Geometric features, such as the sharper curvature at turning roadways have significant effects on turning maneuverability of vehicles. Due to their wider and longer wheelbases, large vehicles have much more pronounced offtracking and occupy greater swept-path widths. This often creates complex driving operations when large vehicles turn at intersections. The turning maneuvers of large vehicles not only determine roadway design, but also influence the safety and efficiency of intersection operations. Studying turning maneuvers mainly consists of analyzing vehicle turning paths and steering operations. This study presents a computational approach that can simulate vehicle turning maneuverability for given roadway alignments, and also checks for coincidence with design standards. This study also presents field experiments involving tractor-semitrailer truck and bus on roadways with different geometric features. The turning paths of wheels and steering wheel operations were recorded simultaneously. Data from field experiments of different turning angles and roadway geometric features are compared with simulated results of computational approach. This study also analyzes the effects of curve radius and geometric features on turning maneuvers. The precise analysis of vehicle turning maneuvers, including turning paths, swept widths, and steering operations, could help roadway and pavement engineers improve traffic safety and efficiency. [ABSTRACT FROM AUTHOR]

Sight distance at the intersection of a minor road (controlled by a stop sign) and a major road is an important element of road safety. Several models have been recently developed for the analysis of sight distance at intersections involving horizontal curves on the major road. All these models assume that the intersection lies within the horizontal curve. There are situations, however, when the intersection lies within one of the tangents of the horizontal curve. This case would adversely affect sight distance, especially when the horizontal curve is sharp and the minor road is close to the horizontal curve. This paper develops a new mathematical model for sight distance analysis that explicitly addresses the case where the intersection lies within the tangents of the horizontal curve. The obstruction may be located within the tangent or within the horizontal curve, or located inside or outside of the horizontal curve. Using the model, graphical aids for the required obstruction distances from the major and minor roads, to satisfy sight distance requirements, are developed. The developed model can be used to evaluate sight distance for existing or new intersections. [ABSTRACT FROM AUTHOR]

Traditional pedestrian level of service measures at signalized intersections are based on pedestrian space and pedestrian delay. However, these measures may not adequately reflect the negative impact of right-turning traffic on pedestrians. This paper presents a statistical analysis using a binary logit model that provides new insights into the factors that affect the likelihood that a pedestrian is compromised (delayed, altered their travel path, or altered their travel speed) in response to traffic turning right (on green) during concurrent vehicle/pedestrian signal timing. The statistical analysis indicates that a number of factors affect the likelihood of a pedestrian being compromised including pedestrian direction of travel, right-turn traffic volume, number of pedestrians crossing, whether the pedestrian arrived late and began crossing after the end of the walk interval, and the crosswalk characteristics including location (downtown versus suburban) and one-way/two-way streets. [ABSTRACT FROM AUTHOR]