Examining Optimal Sight Distances at Rural Intersections

Status: Complete
Report Date: 08/05/2019

Summary:

Of all crashes that occurred at Minnesota intersections from 2008 to 2012, nearly 42 percent involved serious injuries or fatalities. Crashes at uncontrolled rural intersections are often more severe. Drivers at four-way unsignalized intersections are forced to make crossing judgments in situations where there is insufficient sight distance. This study, using a sophisticated driving simulator that was validated by engineers, determined that 400 and 600 feet of sight distance are insufficient at intersections. Drivers performed much better with 1,000 feet of sight distance, both at intersections and on main line roads responding to vehicles running stop signs. Researchers also noted that moving the stop bar closer to the main line at thru-stops would both increase the sight distance of waiting drivers and influence the main line drivers to slow down when approaching intersections. Safety could be increased with this very low-cost change.