A decision model for gap acceptance and capacity at intersections Moshe A. Pollatschek a , Abishai Polus b, * , Moshe Livneh b a Department of Industrial Engineering and Management, Technion, Israel Institute of Technology, Haifa 32000, Israel b Department of Civil Engineering and Transportation Research Institute, Technion, Israel Institute of Technology, Haifa 32000, Israel Received 25 September 2000; received in revised form 7 May 2001; accepted 12 May 2001 Abstract The purpose of this paper is to present a microscopic decision model for driver gap-acceptance behavior when waiting at an unsignalized intersection on the secondary road and also to estimate the resulting in- tersection capacity. The model is based on evaluation of the risk associated with not accepting small gaps against the potential benefit of their acceptance, which is the time saved as a result of shorter waits at the entry line. The model takes into account individual preferences by defining individual critical gap, which is different from the traditional macroscopic critical-gap approach. The latter estimates the critical gap for the entire population of drivers. The paper presents the difference between different driver populations (risk- loving vs. cautious) and shows how this difference actually results in different capacities on the minor road. Ó 2002 Elsevier Science Ltd. All rights reserved. 1. Introduction In spite of continuous traffic growth in most developed nations, the majority of intersections on rural highways and even in suburban areas in these countries, are unsignalized. Some are con- ventional T or cross-intersections; recently more roundabouts are being constructed, particularly in suburban areas, where the hierarchy of the two intersecting roads is similar and the approach volumes are low to moderate. When evaluating the performance of any unsignalized intersection, it is necessary to analyze the capacity of the secondary road and, often, to calculate the anticipated average delay, on the basis Transportation Research Part B 36 (2002) 649–663 www.elsevier.com/locate/trb * Corresponding author. Tel.: +972-4-829-2383; fax: +972-4-627-1212. E-mail address: polus@tx.technion.ac.il (A. Polus). 0191-2615/02/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII:S0191-2615(01)00024-8