Characteristics of red light violators: Results of a field investigation

Motor vehicle crashes at traffic signals are a major source of injuries and property damage, especially in urban areas. Many crashes result from vehicles entering the intersection after the onset of a red light, a traffic violation that may be affected by the duration of the change interval (the yellow and all-red periods of the traffic signal). The purpose of this study was to examine short-term and sustained effects on red-light compliance and potential vehicle conflicts as a result of an increase in change intervals to values associated with the Institute of Traffic Engineers (ITE) proposed recommended practice for determining vehicle change intervals. Data were collected during an experiment in an urban location involving changes in signal timing at some 10 intersections. Observations included the proportion of signal cycles with vehicles entering on a red light and the proportion of vehicles exiting the intersection after the onset of a conflicting green signal. Results indicate that change intervals...

Influence of Traffic Signal Timing on Red-Light Running and Potential Vehicle Conflicts at Urban Intersections

Deceleration characteristics of vehicles are important for intersection design, deceleration lane design, traffic simulation modeling, vehicular emission and fuel consumption modeling, etc. Heterogeneous traffic stream consists of vehicles with wide variation in their physical dimensions, weight to power ratio and dynamic characteristics, which affect their deceleration behaviour. The majority of past studies are restricted to deceleration behaviour study of cars and trucks in homogeneous traffic. The present study aims to analyze the deceleration behaviour of different vehicle types (like truck, car, motorized two and three-wheeler) on Nagpur-Mumbai Express Highway at Wardha, India. Drivers were asked to decelerate their vehicles from their maximum speed to zero speed in the shortest time and their speed profiles were collected using Global Positioning System. Deceleration behaviour of different vehicle types is significantly different. Vehicles with higher maximum speed have higher deceleration time, deceleration distance, maximum and mean deceleration rates during their deceleration manoeuvre. In deceleration manoeuvres, vehicle’s deceleration rate initially increases, attains the maximum deceleration and decreases afterwards. A dual regime model is developed to describe deceleration behaviour over the entire speed range of all vehicle types except cars. For cars, a second order polynomial is proposed.

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Study of Deceleration Behaviour of Different Vehicle Types

The development of an automatic method of safety monitoring at Pelican crossings

A comprehensive investigation of the influence of vehicle type on various aspects of dilemma zone driver behavior, including brake response time, deceleration rate, and red light running occurrence, was performed at six urban or suburban signalized intersections in Wisconsin. Driver behavior data were obtained for 1,275 vehicles that were between 2.0 and 6.5 s upstream of the intersection at the onset of the yellow interval. Each vehicular observation was classified into one of five vehicle type categories: motorcycle, car, light truck (pickup, SUV, van, minivan), single-unit truck (single-unit heavy truck, delivery truck, recreation vehicle, bus), and tractor trailer (multiunit heavy truck). Each observation was also classified by time of day and whether the subject vehicle was part of a platoon. Vehicle type had a statistically significant effect on deceleration rate and red light running occurrence but did not have an effect on brake response time. Deceleration rates were highest for cars and light trucks; single-unit trucks and tractor trailers showed the lowest deceleration rates. Tractor trailers were 3.6 times more likely and single-unit trucks were 2.5 times more likely to commit red light running compared with passenger vehicles. The rates of red light running for cars and light trucks were not substantially different from each other. Time of day (peak versus off-peak) had a statistically significant effect on both deceleration rate and occurrence of red light running. Deceleration rates were significantly higher during off-peak times. Red light running was 1.3 times more likely to occur during peak periods compared with off-peak periods. Platooning had no effect on any of the measures of effectiveness.

Dilemma Zone Driver Behavior as a Function of Vehicle Type, Time of Day, and Platooning

Time-lapse photography was used to study driver behavior associated with the traffic signal change interval at a total of six intersections in the Phoenix and Tucson metropolitan areas. In addition, nighttime studies were conducted at two of these intersections. An evaluation of the time-lapse film permitted the determination of the approach speeds of the vehicles, the average deceleration rates of the stopping vehicles, the perception-reaction times of the drivers of the stopping vehicles, and the distance that the vehicle was from the intersection at the onset of the yellow interval. The distance from the intersection was measured for both the stopping vehicles as well as those that proceeded through the intersection. The results of the study indicated that the mean deceleration rates at the six sites ranged from 7.0 to 13.9 ft/s/s, and the mean value for all observations was 11.6 ft/s/s. The observed mean perception-reaction time was approximately 1.3 s while the 85th percentile times ranged from 1.5 to 2.1 s. Comparisons of intersections with yellow only versus yellow plus all-red intervals produced mixed results in terms of differences in observed behavior. Even for intersections with the same change interval design, there were cases where the observed deceleration rates were significantly different.

Evaluation of driver behavior at signalized intersections (discussion)

Driver and traffic characteristics associated with change intervals were studied at five intersections in the Tucson metropolitan area. The field studies were conducted to document the influence of (a) the variation in the duration of the yellow interval, (b) the effect of enforcement, and (c) intersection approach grades. Before and after studies were used at two of the intersections to evaluate the influence of extending the duration of the yellow interval. Generally, the major difference that resulted from a 4-sec yellow interval rather than 3 sec was the reduction in the percentage of the last vehicles through the intersection that entered on the red signal indication. The effect of enforcement was tested with a police vehicle located at the intersection approach. Although there was a reduction in the percentage of vehicles that entered the intersection on the red signal interval, other measures of driver and traffic characteristics generally showed no significant difference.

Traffic characteristics during signal change intervals (abridgment)

Vehicles stopping at signalized intersections were examined for the purpose of evaluating the validity of the common assumption of constant and uniform deceleration rates. The data set consisted of the first vehicles to stop upon the onset of the yellow signal interval with measurements of the initial approach speed, deceleration time, and deceleration distance. The deceleration rate may be computed using only two of the three measured values; thus the rate for each vehicle can be determined by three differnt equations. With nonuniform deceleration profiles, the equations will produce different values; and the degree of nonuniformity can be determined by comparing the differences in the computed deceleration rates. The analysis of the field observations indicated that 69% of the vehicles demonstrated deceleration profiles associated with nonuniform deceleration rates. Furthermore, the deceleration profile and the degree of nonuniformity were found to be a function of the initial approach speed.

An evaluation of vehicle deceleration profiles

Data from field studies of intersections in Arizona and information from the literature were used to make an in-depth examination of the traffic signal change interval. This examination included a review of the traditional concept and theory on which the determination of the change interval has been based and an evaluation of the applicability of this theory. The analysis of driver behavior and characteristics indicates that the majority of drivers do not conform to the model, which assumes a constant or uniform deceleration rate. In fact, the deceleration profile is related to the approach speed. An analysis of the first vehicle to stop at an intersection and the last vehicle to clear the intersection was made based on the time from the intersection at the onset of the yellow interval. This analysis revealed that the time for the last vehicle to clear the intersection is more critical in the design of the yellow interval. It is concluded that a uniform 4-sec yellow interval would be acceptable.

A reassessment of the traffic signal change interval

Field studies were conducted in the Phoenix and Tucson metropolitan areas for the purpose of comparing the operational differences between leading and lagging left-turn signal phases. Delay studies were conducted in both areas at isolated intersections, and the influence on signal system progression was evaluated at three locations in the Phoenix area. In both areas, the lagging left-turn phases do not utilize overlaps even though phase overlaps were used with the leading left-turn operations. Intersections with protected-only as well as protected-plus-permissive left turns were included. The study involved a before-and-after analysis of the intersection as well as arterial operations. For the individual intersections, the field studies found that the intersection delay is significantly greater with the lagging left-turn operation. This finding was true for both of the metropolitan areas. In terms of the signal system progression, no significant differences were found in progression among the leading, lagging, and mixed operations.

Robert H Wortman

Papers

Evaluation of driver behavior at signalized intersections (discussion)

Traffic characteristics during signal change intervals (abridgment)

An evaluation of vehicle deceleration profiles

A reassessment of the traffic signal change interval

Operational comparison of leading and lagging left turns