Operational Considerations of Passing Zones for Two-lane Highways: Spanish Case Study

[EN] The U.S. Highway Capacity Manual (HCM 2010) methodology is used in Spain to evaluate traffic operation and quality of service. In two-lane undivided highways, the effect of limiting where drivers could pass slower vehicles, or passing restrictions, is considered through the percentage of no-passing zones. This measure does not account for how passing opportunities are distributed along the road. The objective of this research was to evaluate the effect percentage of no-passing zones and average passing zone length on two-lane, and incorporate them in the analysis methodology, if significant. The TWOPAS microsimulation program was calibrated and validated to the Spanish conditions. Passing restrictions had little effect on average traffic speed (ATS), with differences lower than 6 km/h between a segment of road with no passing restrictions and a segment of a road with 100% of length with passing restriction. Conversely, passing restrictions can increase percent time spent following (PTSF) up to 30%. Increasing the passing zone length beyond 2,000 m does not improve PTSF. The new models could be used to better estimate traffic operation on Spanish two-lane highways. The research was funded by the Spanish Ministry of Economy and Competitiveness [TRA2013-42578-P], and has been partially developed as a result of a mobility stay at the University of Florida funded by the Spanish Ministry of Economy and Competitiveness [EEBB-I-15-09970]. The research was completed with the support of the FPI Research and Teaching Fellowship of the Spanish Ministry of Economy and Competitiveness [BES-2011-044612] and the TUM University Foundation Fellowship (TUFF) for international postdocs. We would like to thank Dr. Lemke from the Bundesanstalt fur Strassenwesen (Federal Highway Research Institute) for providing the final report of the research project FE 16.0015/2009 (23). This work was supported by the German Research Foundation (DFG) and the Technical University of Munich (TUM) in the framework of the Open Access Publishing Program. Moreno Chou, AT.; Llorca Garcia, C.; Washburn, S.; Bessa Jr., JE.; García García, A. (2018). Operational Considerations of Passing Zones for Two-lane Highways: Spanish Case Study. PROMET - Traffic&Transportation. 30(5):601-612. https://doi.org/10.7307/ptt.v30i5.2776