Reliability Analysis for Roadway Curves with Horizontal Sightline Obstructions

Daniel J. Cook, Douglas W. Harwood, Ingrid B. Potts, Eric T. Donnell, Bachir Hamadeh

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Objects on the inside of a horizontal curve may limit the stopping sight distance (SSD) available to drivers. Crash analysis shows that SSD-related crashes on horizontal curves are limited in number and difficult to quantify. As an alternative, a reliability analysis model was developed to quantify the number of drivers per year who may encounter a stopped vehicle in a sight-restricted area, creating an opportunity where an SSD-related crash might occur on a roadway with a sight obstruction on the inside of a horizontal curve. The model considers roadway alignment in three dimensions. The model formulation is documented and an analysis of the sensitivity of crash opportunities to traffic volume and offset to a sight obstruction is performed. A sensitivity analysis of the reliability analysis model shows that the percentage of vehicles that may encounter a crash-involved vehicle or a queue of stopped vehicles over the course of a year can range from essentially zero to a value approaching 1% of the total yearly flow. The reliability analysis model is a flexible tool that can be used by planners and designers to compare, in a relative sense, the need for sight distance improvements on specific horizontal curves.

Original languageEnglish (US)
Pages (from-to)611-622
Number of pages12
JournalTransportation Research Record
Issue number8
StatePublished - Aug 1 2019

All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • Mechanical Engineering


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