On two-lane rural roads, passing maneuvers allow faster vehicles to pass the slower ones, in order to reduce interferences and improve level of service. However, to pass a slower vehicle, it is necessary to occupy the opposing lane, which had a significant impact on road safety and road operations. For this reason, passing is only permitted at certain parts of the road, where, according to geometric design and marking guidelines, there is sufficient passing sight distance. Passing sight distance is defined as the distance required to pass a slower vehicle, when a third opposing vehicle is approaching at the same time. A huge dispersion in criteria, theoretical models and observations was found in the literature. This PhD Thesis carried out a wide field study of passing maneuvers on two-lane rural roads in the surrounding of Valencia (Spain). Video was recorded both from external static points and from an instrumented vehicle, which travelled at slightly slow speeds and was passed by others under normal traffic conditions. The vehicle was equipped with video cameras, GPS and laser rangefinders. These methods characterized up to 1179 passing maneuvers in a high number of variables, such as type and number of impeding vehicles, available sight distance, speed of vehicles, age and gender of the passing driver or lighting conditions. The effect of these factors was analyzed and passing models were formulated. Firstly, passing gap acceptance modeled drivers’ decisions before passing; secondly, passing sight distance models quantified drivers’ requirements when passing. A probabilistic approach was used to exploit these models, which facilitated the interpretation of the probability of passing and the probability of a passing gap to be sufficient for a driver. Therefore, the risk related to passing was analyzed, and compared with objectives safety measures, such as number of passing related crashes. These results were used to assess the risk of current Spanish geometric design and marking guidelines. Thereafter, a unique criterion was determined, minimizing the risks of head-on collisions and the probability of no-passing zone violations. Additionally, the PhD thesis includes the development of a passing model integrated in a microsimulation model for two-lane rural highways      «

On two-lane rural roads, passing maneuvers allow faster vehicles to pass the slower ones, in order to reduce interferences and improve level of service. However, to pass a slower vehicle, it is necessary to occupy the opposing lane, which had a significant impact on road safety and road operations. For this reason, passing is only permitted at certain parts of the road, where, according to geometric design and marking guidelines, there is sufficient passing sight distance. Passing sight distan...     »