Evaluation of Passing Process on Two-Lane Rural Highways in Spain with New Methodology Based on Video Data

Abstract

Drivers need enough Passing sight distance (PSD) to pass slower vehicles with safety. This can help to improve traffic operation on two-way two-lane highways. Existing models propose different values of PSD, according to different assumptions. Only in some cases these models were based on field data of passing maneuvers.This research proposes the design of a new methodology to observe passing maneuvers on existing highways with help of 6 video cameras installed on a fix point next to passing sections. The use of a larger number of cameras allows the complete registration of trajectories along the entire passing zone, with uniform image resolution. The methodology was applied to register a sample of 234 maneuvers on 4 passing zones. Trajectories of 58 of them were completely described and analyzed using specific restitution software.Results are compared with existing PSD models. AASHTO model proposed distances travelled on the left lane are similar to average observed distances if the passed vehicle is one truck, and between 50 and 100 m higher if one passenger car is passed. Higher differences, over 100 m, were found between measured data and PSD model of Hassan et al., especially at high design speeds. Observed average speed difference between passing and impeding vehicles is significantly higher than in all models.Variables with strongest influence on the time and distance travelled on the opposing lane are: type and speed of the passed vehicle and the length of the passing zone. Left lane time and distance increase with this length.LLORCA, C. and GARCÍA, A.

Sight Distance Standards Based on Observational Data Risk Evaluation of Passing

“…Previous research work have collected data of passing maneuver under naturalistic conditions, in order to compare the existing standards with the observed behavior or to analyze other factors involved in the passing process. Recently, some studies have recorded passing maneuvers from external positions (13,14) as well as from instrumented vehicles (15,16). Some of these observations showed that existing design criteria, such as the US previous AASHTO standard could be too conservative.…”

“…Using a combination of video, GPS and laser rangefinder data, following variables were measured ( The length of passing and impeding vehicle Li and Lp were obtained after identifying its brand and model. The selection of the previous variables followed previous research studies (9)(10)(11)(12)(13)(14)(15). These variables provided information about passing duration, passing speeds and distance traveled during passing.…”

“…Average vehicle lengths from a previous study (14) were assigned to each vehicle category to obtain the lengths distribution. The analysis considered both heavy and light impeding vehicles, but only light passing vehicles, according to observations.…”

“…Data collection has been based on video recording of passing maneuvers under naturalistic conditions, which minimizes the influence of observers. Two methodologies have been used to record passing maneuvers (14,16).…”

The Directness Factor

“…Levels of service of those highways are increased due to the existence of passing zones, where 4 sufficient passing sight distance is provided. 5 This maneuver is one of the most complex and dangerous on two-lane highways. It involves 6 several decision processes, strongly affected by human factor, road geometry and vehicle 7…”