Effect of Centerlines on Prevailing Traffic Speeds and Lateral Lane Positioning on Low-Speed, Two-Lane, Two-Way Urban Streets

Summary:

High vehicle speeds significantly increase the likelihood of fatal and serious injury crashes. To support efforts to improve safety on lower-volume urban roads, this project examined how centerlines and edgelines affect vehicle speeds and lateral positioning. Results showed that vehicles traveled more slowly and farther from the opposing traffic lane when centerlines and edgelines were not present. Drivers also provided significantly more lateral space to parked vehicles and shoulder bicyclists when no centerline was present. Based on these findings, centerlines should be optional on relatively straight two-lane urban streets with speed limits below 35 mph, widths greater than 20 feet and average annual daily traffic volumes below 6,000.

Final Deliverables:

• Effect of Centerlines on Prevailing Traffic Speeds and Lateral Lane Positioning on Low-Speed, Two-Lane, Two-Way Urban Streets (Report #2026-30)
• Exploring the Speed and Safety Impacts of Pavement Markings (Research Summary)

Related Materials:

• New Project: Effect of Centerlines on Prevailing Traffic Speeds of Low-Speed, Two-Lane, Two-Way Roads in Urban Contexts  (Blog Post)

Related Research: