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                Safety Effects of the Conversion of Rural Two-Lane Roadways to Four-Lane Roadways
FHWA-RD-99-206.pdf (111.99 KB)
      
  Publication Information
                  Publication Type:Summary Report
                  Publication Number:FHWA-RD-99-206
              Abstract:As congestion on two-lane rural roads increases, there is increasing interest in conversion to a four-lane divided facility within the same corridor. The authors have attempted to estimate the benefits of such conversions by developing cross-sectional models producing crash rates for typical sections of two- and four-lane roadways in California, Michigan, North Carolina, and Washington. Predicted crash reductions for conversion from most typical two- to four-lane divided sections ranged from 40-60 percent. The reduction due to conversion to a four-lane undivided configuration is much less well defined, ranging from a 20 percent reduction to a slight increase. Future research needs include (a) verification of the undivided four-lane results, (b) additional information on the effects of driveways, (c) estimates for higher levels of two-lane average daily traffic, (d) expansion of the outcome variable to include crash severity, and (e) verification of all results by before-and-after studies of actual conversions.
              Publishing Date:November 1999
                                      Author(s):Council,
    
          Forrest
              Stewart,
    
          J. Richard
              Publishing Office:Office of Corporate Research, Technology, and Innovation Management
                  FHWA Program(s):Research
              Safety
              AMRP Program(s):Safety Data and Analysis
              FHWA Activities:Highway Safety Information System
              Subject Area:Safety and Human Factors U.S. DEPARTMENT OF TRANSPORTATION

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