SD44 Speed Warning System

Near Mileage Reference Marker 38 on SD44 west of Rapid City, eastbound traffic sometimes encounters a combination slippery pavement, steep grade and a sharp curve. The location can catch motorists by surprise despite a warning sign indicating an 8% grade. The situation is worse during winter because the area is shaded throughout most of the day, prolonging frost conditions. Inspections conducted for the Department's Roadway Safety Improvement (RSI) program identified a combination of curvature, grade, and vehicle speed as factors contributing to accidents at the location. Since 1996, three accidents at this site have been attributed to ice or frost, and 19 have been attributed to the curve. Guardrail, arrow, and chevron signs are in place for both east- and westbound traffic. Flashing lights and rumble strips were added during the summer of 2000. In 1999 through 2001 alone 8 accidents were attributed to the curve. The mountainous terrain makes geometric improvements prohibitively costly. Improvements to the site include rumble strips, increased warning sign size, and continuous flashers. The work proposed at this site would include installation of instrumentation to monitor the surface condition and detect the speed of approaching vehicles. A vehicle approaching at speeds inappropriate to surface conditions would receive a warning of excessive speed. The system would communicate road conditions to SDDOT's Road Condition and Reporting System (RSRS), the database for 511 Travel Information and other information systems. The system must therefore comply with National Transportation Communications for ITS Protocol (NTCIP) standards for communications with roadside equipment and environmental sensor stations. This project entails developing plans and specifications for the system, and installing it by maintenance or under a separate installation contract. SDDOT's future RSI reviews will determine how much accidents decrease.


  • English


  • Status: Active
  • Contract Numbers:


  • Sponsor Organizations:

    South Dakota Department of Transportation

    Transportation Building, 700 E Broadway
    Pierre, SD  United States  57501
  • Project Managers:

    Becker, Jonathan

  • Principal Investigators:

    Becker, Jonathan

  • Start Date: 20040901
  • Expected Completion Date: 0
  • Actual Completion Date: 20051231
  • Source Data: RiP Project 12579

Subject/Index Terms

Filing Info

  • Accession Number: 01458298
  • Record Type: Research project
  • Source Agency: South Dakota Department of Transportation
  • Contract Numbers: SD2004-11
  • Files: RiP, STATEDOT
  • Created Date: Jan 3 2013 12:39PM