Four-Lane to Three-Lane Conversion Case Study: State Highway Through a Small Town

Thursday, March 20, 2008 - 4:00pm

About the Event

The conversion of four-lane undivided roadways to three lanes (one lane in each direction with a two-way left-turn lane) is not a routine consideration. The successful implementation of this type of conversion requires additional attention to certain details and close consideration of a large number of factors.

This presentation focuses on the factors/process that could be followed to evaluate the feasibility of four-lane to three-lane conversions. The factors recommended for consideration in past research will be identified, and the details of those analyzed for a case study location will be provided. The characteristics of particular interest along a case study segment will be described. These characteristics included the segment's desired and actual roadway function and vehicle speed, intersection operations and design, business access, truck traffic, pedestrians, right-of-way availability, and a nearby parallel railroad track.

There will also be a discussion of the advantages and disadvantages of the four-lane to three-lane conversion in comparison to other proposed cross-section alternatives. The observations and lessons learned during the impact evaluation of this case study segment will be noted.


Keith K. Knapp, Research Manager, Center for Excellence in Rural Safety, Humphrey School of Public Affairs