Since 1992, New Zealand's 10,000 km State Highway network has been regularly surveyed to collect data on horizontal curvature, gradient and cross-fall at 10-m intervals. A number of initiatives have been developed that make use of this valuable data source, particularly for rural highways. For example: general crash risk relationships based on Poisson generalized linear models have been developed that can identify the effect of changes to key geometric variables; speed profiles have been developed for highway strategic studies, enabling curves that are deficient to the surrounding road environment to be highlighted; comparisons of cross-fall and curvature enable sections of highway that fail to meet design standards to be readily identified; sight distances can be generated from the geometry data, to assist with the evaluation of passing lanes and no-overtaking areas; the effects of geometry on long-vehicle paths along routes have been used to estimate the required remedial investment; road geometry data can establish an appropriate curve advisory speed to post on warning signs; and fixed-length geometry data have been used to derive variable-length geometric elements. The applications enable practitioners to be proactive in identifying and treating hazardous or congested sections of highway. They also minimize the additional field survey work required. This paper describes these developments and the benefits derived, through specific practical examples. It also discusses some of the difficulties experienced in using these data and potential future applications.
Samenvatting