New Zealand's State Highways were surveyed in 1992 using the Road Geometry Data Acquisition System (RGDAS). This system collected data on horizontal and vertical alignment, gradient and crossfall. A number of initiatives have been developed that make use of this valuable data source. General crash risk relationships based on Poisson Generalised linear models have been developed that can identify the effect of changes to key geometric variables. Geometry data has also been combined with crash and traffic data to develop crash rates for various terrain situations. Speed profiles have been developed for highway strategic studies, enabling curves that are deficient to the surrounding road environment to be highlighted. Sight distances can be generated from the data to assist with the evaluation of passing lanes and no-overtaking areas. Road geometry data can also establish an appropriate curve advisory speed. These applications enable practitioners to be proactive in identifying and treating hazardous sections of highway. This paper describes these applications, through specific practical examples, and outlines potential future uses for road geometry data. (A)
Abstract