Influence of Experimental Advisory Exit Speed Limit on Freeway Exit Ramp Traffic Speeds

Many crashes occurred around freeway exit ramp areas due to speeding and speed variance, especially in China. Traditionally, a posted ramp speed limit will be installed around physical gore area to manage speed around the area. Unfortunately, the field study showed that speeding and speed variance haven’t been improved too much after introduction of posted ramp speed limit. An additional speed limit on deceleration lane may be needed to accommodate the speed changes ahead of physical gore, which could be functioned by Advisory Exit Speed Limit (AESL). However, no systematic research on the influences of AESL and its application has been reported yet. Thus, the primary objective of the paper is to investigate its influences on exiting vehicles’speed. A general method was developed to measure AESL and facilitate the application in different Sites. To achieve this goal, three Sites with same exit ramp configuration in China were selected and two Scenarios (with AESL/ without AESL) were investigated to quantify the influences. With two hours data collection for each Scenario at each Site, the speed and deceleration rate of approximately 480 vehicles were obtained. Meanwhile, t-test was introduced to verify the differences in speed between the two Scenarios. Results showed that with AESL, the mean speed and the 85thpercentile speed reduced significantly at all three Sites, while only one Site performed a significant reduction in speeding. Unfortunately, no obvious improvement on speed variance achieved at the three sites, even there were some tendencies on speed decrease on deceleration lane. The paper can provide researchers, managers and engineers with reasonable foundations, when determining the necessity and ways to install AESL. The proposed methodology will be especially helpful in China and other developing countries with similar exit ramps.

• Supplemental Notes:
  • This paper was sponsored by TRB committee AHB50 Traffic Control Devices.
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Ma, Yongfeng
  • Sheng, Fei
  • Zhang, Wenbo
  • Zhang, Cong
• Conference:
  • Transportation Research Board 92nd Annual Meeting
  • Location: Washington DC, United States
  • Date: 2013-1-13 to 2013-1-17
• Date: 2013

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: 18p
• Monograph Title: TRB 92nd Annual Meeting Compendium of Papers

Subject/Index Terms

• TRT Terms: Deceleration; Field tests; Gore area; Off ramps; Speed limits; Speed signs
• Geographic Terms: China
• Subject Areas: Highways; Operations and Traffic Management; I73: Traffic Control;

Filing Info

• Accession Number: 01478353
• Record Type: Publication
• Report/Paper Numbers: 13-4976
• Files: TRIS, TRB, ATRI
• Created Date: Apr 15 2013 1:15PM