Road geometry of local roads

Road geometry

As part of the development and implementation programme to support the introduction of SCANNER surveys on all local roads in England, this research provided a detailed investigation of the potential for using measurements of road geometry, on their own or combined with other measurements, to indicate the condition and maintenance requirements of all types and classes of local road, from principal roads to minor unclassified roads.

The SCANNER survey machines collect a range of data about the geometry (gradient, cross fall and curvature, etc.) of roads. This research investigated how it could be used to establish road user requirements (including road safety), road service level (in relation to the road functional hierarchy) and maintenance requirements.

The project was carried out by Scott Wilson Pavement Engineering with the University of Nottingham. The final project report is here Geometry of local roads

The report concludes that there is a vast array of potential uses of road geometry information, but that all of these uses require integration with other data sets. Consequently it will become increasingly important to convert traditional linear road carriageway referencing systems to more widely used geo-referencing systems such as OS co-ordinates of WGS84.

SCANNER survey vehicle positioning can readily be achieved, to the accuracy required, when there is good GPS coverage. However a more expensive approach, including an Inertial Navigation System, is required to achieve the specification where GPS coverage is less adequate.

Although this research did not identify any strong candidates for the use of geometry data to assist in reporting road surface condition, it identified an enormous number of potential uses for road geometry data, held as inventory information within a pavement management system. The report identifies 124 potential uses for geometry data, in combination with 30 other data sets, to provide information related to road user requirements, road service level or road maintenance requirements.

The report demonstrates how geometric data might be used through three examples. Road user requirements from the point of view of motorcyclists; road service level through the comparative analysis of incident and geometry data; and maintenance requirements by identifying lengths with unusual geometry.

The results of this research project were incorporated in the SCANNER User Guide and Specification for 2007.