Comparing Alternatives of a 2+1 Highway with Two-lane Highways through Simulation

The rural transportation system is composed mostly of two-lane highways. In recent year 2+1 highways have been built in many countries. 2+1 highways provide a continuous three-lane cross section with alternative passing. Thus, they reduce drivers stress to find a passing gap on the on-coming traffic, as well as minimize the likelihood of head-on collisions with opposing vehicles. 2+1 highways may offer advantages when traffic volumes may not be high enough to justify a four-lane highway, but still higher than the volume that can be served by a two-lane highway, and if a high number of head-on collisions or passing-related collisions happen. This paper summarizes a research seeking to estimate potential operational benefits of converting a Spanish two-lane highway into a 2+1 highway by using traffic simulation. Alternative designs for transition zones have be implemented. The results show that average travel speed was sustainably higher considering the 2+1 highway for traffic flows below 1,200 veh/h. From that point, average travel speed dropped dramatically. Similar results were obtained for PTSF. Transition zone design affected traffic performance: the longer the transition zone, the lower the quality of service. Comparing the Spanish and German designs, the German transition zone provided between 30 and 40 % better results, in both ATS and PTSF. Even though the results suggest modifying the current Spanish design, more research is required to verify that the German design is safe for Spanish drivers. The results and conclusions are valid within the simulation range and for the considered assumptions.

• Supplemental Notes:
  • This paper was sponsored by TRB committee AHB40 Standing Committee on Highway Capacity and Quality of Service.
• Corporate Authors:

  Transportation Research Board

  ,    
• Authors:
  • Romana, Manuel G
  • Martin-Gasulla, Marilo
  • Moreno, Ana Tsui
• Conference:
  • Transportation Research Board 98th Annual Meeting
  • Location: Washington DC, United States
  • Date: 2019-1-13 to 2019-1-17
• Date: 2019

Language

• English

Media Info

• Media Type: Digital/other
• Features: Photos; References; Tables;
• Pagination: 6p

Subject/Index Terms

• TRT Terms: Crash characteristics; Highway design; Highway safety; Passing; Passing sight distance; Traffic flow; Traffic speed; Turning lanes; Two lane highways
• Geographic Terms: Germany; Spain
• Subject Areas: Design; Highways; Safety and Human Factors;

Filing Info

• Accession Number: 01698178
• Record Type: Publication
• Report/Paper Numbers: 19-01089
• Files: TRIS, TRB, ATRI
• Created Date: Mar 1 2019 3:51PM