The estimation of highway geometry for road accident analysis

There is no documentation recording the geometric alignment of the greater part of Britain's road network. Highway geometry is an important factor in road accidents, particularly in rural areas where speeds are high and injur ies tend to be severe and numbers of sites requiring investigation are larg e. Hence there is an important role for new tools that can estimate the geo metry, for use in accident research and in other applications that depend o n two- or three-dimensional visualization without on-site surveying. This p aper describes methods for estimating horizontal and vertical curvature fro m digital data sources and the development of a geographical information sy stem (GIS) application that can link accident data to the alignment. It is anticipated that such an application will provide a platform for future res earch to improve the understanding of the relationships between accident fr equency and highway geometry.