Head-On Collisions: Appendix 6

Profiles of State and Local Implementation Efforts: Strategy 18.1 A3 (Iowa Department of Transportation)

Emphasis Area
18.1-Reducing accidents involving head-on collisions

Objective
18.1 A-Keep vehicles from encroaching into opposite lane

Strategy
18.1 A3-Provide wider cross-sections on two-lane roads

Agency and Jurisdiction
Iowa DOT

Problem(s) Identified
High traffic demand on two-lane roads, but inadequate ROW for building multilane facilities.

Goals and Objectives Established
Increase traffic flow without decreasing safety on high-volume two-lane roads.

Description of Strategy Implemented
The Iowa "Super Two" design is proposed for use in a location where the facility should be four-lanes due to traffic demand, but where there is inadequate right-of-way or other constraints. The elements of the design are a 70-mph design speed, truck-climbing lanes, occasional passing lanes, long turning lanes at intersections, offset left-turn lanes, 10-ft-wide shoulders (may be paved), and a 13.5-ft travel lane.

Summary of Implementation Effort
Currently, the Iowa DOT is planning these conversions for six corridors. There is some concern that the 70-mph design speed could lead to possible decreases in safety, unless roadside improvements are also made. Such improvements may not be possible in locations having ROW limited.

Summary of Results
No results at this time.

Contact Person and Information
Tom Welch, Iowa DOT, 515-239-1267, Tom.Welch@dot.state.ia.us