This report describes work carried out to support the specification for SCANNER (Surface Condition Assessment of the National NEtwork of Roads) surveys of the local road network by developing the use of surface texture measurements on local roads. The project objectives include investigation into the variation of texture depth along and across local roads, the potential use of texture depth measurements to infer information about skid resistance, the presence of localised surface defects, tyre noise generation and the characterisation of road surface maintenance condition of local roads.
The work carried out has sought to address these objectives in turn, and the report describes the following. An investigation of the texture characteristics specific to local roads has considered the use of existing techniques and texture depth thresholds used on the trunk road network, and the modification of these techniques that would be needed to meet the requirements of the local road network, particularly for B and C roads. In order to detect localised surface texture defects, the use of additional lasers - already carried by most survey vehicles – to make measurements of texture across the full road width, instead of on a single line in the vehicle wheel path, has been undertaken. The correlation between texture depth and skid resistance has been studied to determine whether or not measurements made by SCANNER vehicles could provide some surrogate measure that would indicate the presence of inadequate skid resistance on typical local road surfaces. The various sources of noise generated by vehicles using local roads have been examined to identify the feasibility of using measurements made by SCANNER to indicate sections of road liable to cause higher levels of noise.
Finally, based on the conclusions of these investigations, recommendations are made for necessary enhancements to the specification for SCANNER surveys.

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