GAPS ACCEPTED AT STOP-CONTROLLED INTERSECTIONS

Gap-acceptance data are used to determine intersection sight distance, capacity, queue length, and delay at unsignalized intersections. They have also been used to determine the need for a traffic signal, the capacity of a left-turn lane, and warrants for left-turn signal phasing and storage lanes. A field study was performed to determine the gap-acceptance values of truck and passenger car drivers at six intersections. Each intersection was formed by two 2-lane roads; the minor road was controlled by a stop sign. The data obtained in the field were evaluated by three methods: Greenshield, Raff, and logit. The findings from the field studies were summarized into generalized values. Passenger car drivers had a 50% probability of accepting a gap of 6.5 sec for both left and right turns and an 85% probability of accepting a gap of 8.25 sec at a moderate- to high-volume intersection. A 10.5-sec gap represented the 85% probability of accepting a gap at an intersection where accepted gaps were influenced by low volume and the intersection's geometry. Truck drivers' 50% probability of accepting a gap was 8.5 sec. At a high-volume location, 85% of the truck drivers accepted a 10-sec gap; at a low-volume location, 15.0 sec was the accepted gap value.

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  • This paper appears in Transportation Research Record No. 1303, Geometric Design Considerations 1991. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
• Authors:
  • Fitzpatrick, Kay
• Publication Date: 1991

Media Info

• Features: Figures; References; Tables;
• Pagination: p. 103-112
• Monograph Title: Geometric design considerations, 1991
• Serial:
  • Transportation Research Record
  • Issue Number: 1303
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Automobile drivers; Field studies; Gap acceptance; Left turns; Right turns; Stop signs; Traffic volume; Truck drivers; Two lane highways; Unsignalized intersections
• Uncontrolled Terms: Two-way stop control
• Subject Areas: Design; Highways; I20: Design and Planning of Transport Infrastructure;

Filing Info

• Accession Number: 00616594
• Record Type: Publication
• ISBN: 030905110X
• Files: TRIS, TRB, ATRI
• Created Date: Nov 30 1991 12:00AM