Improving Safety and Operations with Low-Cost Freeway Bottleneck Removal Projects

Providing safe and efficient roadways are two of the key objectives of any transportation agency. Many agencies are currently struggling with funding shortfalls and are unable to improve the roadway system in order to keep up with the pace of growth and development. Projects that can improve both the safety and efficiency of the roadway system without expenditure of major resources should be highly desirable. One type of project that is experiencing more attention nationwide is low-cost freeway bottleneck removal projects that can be quickly implemented. These projects mitigate congestion and improve travel reliability and safety by reducing crash rates. Bottleneck improvements typically involve solutions such as re-striping merge/diverge areas to better serve demand, converting a short section of shoulder to travel lanes, modifying weave areas, ramp modifications, and adding of auxiliary lanes. This paper will report on successful bottleneck removal programs in four metropolitan areas: Austin, Dallas-Fort Worth, Minneapolis-St. Paul, and Phoenix. Evaluations of bottleneck removal projects in these jurisdictions have consistently shown that significant operational and safety benefits have been realized for little cost. Benefit/cost ratios as high as 400:1 have been found, with the lowest ratio being 3:1; implementation costs ranged from $8,000 to $10.5 million. Injury crash rates were generally lower after implementation, up to 76 percent lower in one case, because the improvements generally return the freeway speeds to near free-flow conditions and there is no longer a high speed differential. Guidelines for identification, analysis and removal of freeway bottlenecks based on the successful programs are also provided