The conversion of four-lane undivided roadways to three lanes (one lane in eachrndirection with a two-way left-turn lane) is not a routine consideration. The successfulrnimplementation of this type of conversion requires additional attention to certain details andrnclose consideration of a large number of factors. This paper focuses on the process followed tornevaluate the feasibility of four-lane to three-lane conversions. The factors recommended forrnconsideration in past research will be identified and the details of those analyzed for a case studyrnlocation provided. The characteristics of particular interest along the case study described werernits desired and actual roadway function and vehicle speed, intersection operations and design,rnbusiness access, truck traffic, pedestrians, right-of-way availability, and a nearby parallel railroadrntrack. This paper discusses the advantages and disadvantages of the four-lane to three-lanernconversion in comparison to other cross section alternatives. It concludes with a summary of thernobservations and lessons learned during the impact evaluation of the four-lane to three-lanernconversion and the identification of critical factors that should be considered early in the process.rnA planning level evaluation of these critical factors should help determine whether the four-lanernto three-lane conversion should be included as an alternative in a more detailed analysis.
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