Use of Vehicle-Collected Data to Calculate Existing Roadway Geometry

The Federal Highway Administration has designated Highway Design Practices and Criteria as a high-priority research and development area. New design standards need to be developed to provide quantitative guidance on alignment consistency, based on the safety performance of a series of (not isolated) roadway features. Geometric information collected through a datalog vehicle for the entire State Trunk Highway System in Wisconsin provides the opportunity to identify and analyze such series of roadway features. An algorithm was developed to produce horizontal curve length, degree of curve, deflection angle, and maximum superelevation. The algorithm was validated for a two-lane highway. Software was developed to produce plan views, color-code curves to the left (right), and tangents, and to display numeric information (e.g., length of curve, degree of curve) for any chosen highway segment. Integration of the developed algorithm with a GIS base map was demonstrated. Availability of systemwide geometric information allows exhaustive searches of geometrically deficient highway segments and the identification of curve-tangent-curve combinations with prespecified geometries.