Skid Resistance Policy (Strategy)
1.1 The aggregate in the surface of the carriageway contributes to the skid resistance between vehicle tyres and the surface. When a new surfacing is laid the aggregate properties are specified in accordance with national guidance with a view to providing an appropriate level of skid resistance throughout the life of the surface.
1.2 However, many factors can affect the rate and extent to which an aggregate will wear and or polish under any particular circumstances so the national guidance cannot be relied upon absolutely. Accordingly, to ensure risks are managed effectively, there is a need to monitor skid resistance in service, particularly on the more heavily trafficked parts of the network. This document outlines Hampshire County Council’s policy for monitoring and maintaining the skid resistance of the road network.
2. Relevant Standards and Documentation
2.1 Well-maintained Highways: Code of Practice for Maintenance Management.
2.2 The Highways Agency Standard HD28/04 ‘Skid Resistance’.
2.3 HCC Skid Resistance Procedure
3.1 This Policy follows recommendations set down in Well-maintained Highways: Code of Practice for Maintenance Management, clarified to reflect the detailed procedures followed by Hampshire County Council. The relevant section of the Code of Practice is based on Highways Agency Standard HD28/04, Skid Resistance, modified for use on local authority highway networks.
3.2 In Hampshire skid resistance testing is carried out routinely on the Critical Network (defined below) and additionally, on a site specific basis, anywhere on the network where the surfacing is suspect or where there is a high concentration of wet skid accidents.
4. Routine Testing
4.1 Routine testing is carried out on a network basis using SCRIM according to the frequency and procedures stated in the Skid Resistance Procedure. Following data processing a list of prioritised sites is produced for signing and/or further investigation as appropriate.
5. Site-specific testing
5.1 Site specific testing is normally undertaken by the County Highways Laboratory using the Griptester or, occasionally, using the Pendulum skid resistance tester.
6. Critical Network
6.1 The critical network comprises all principal roads (local A roads), all B class roads and those C class and unclassified roads which are more heavily trafficked, have relatively high HGV flows, form major diversion routes or have characteristics similar to carriageway hierarchy 3a Main Distributor in the Code of Practice for Highway Maintenance Management. In addition some routes with a known accident history shall be considered for routine assessment irrespective of their traffic loading or strategic importance.
7. Test Methods
7.1 Network scale testing shall normally be carried out using the SCRIM. Raw data from this machine is processed by fitting against the referenced network of sections and comparing the levels with assigned investigatory levels.
7.2 Shorter length site-specific surveys are normally tested using the County Highways Laboratory’s Griptester. As no network fitting is required results can be reported soon after testing if necessary. For very small areas of carriageway the Stanley portable skid resistance tester (pendulum test) may be used.
7.3 Where necessary the results are factored to adjust for seasonal variation to calculate equivalent mean summer skid resistance values.
7.4 In all cases results shall be compared with defined investigatory levels of skid resistance to assess their significance and to take the appropriate actions as described in the procedure document.
8. Investigatory Levels
8.1 The approach followed for setting investigatory levels is described in the Procedure. Investigatory levels are reviewed following a site investigation and are set by staff authorised to do so.
Version No: 1.2
Effective from: 14/10/2010
If copied or printed, this document should be treated as uncontrolled and correct only at the date it was copied or printed.