A GripTester trial was carried out in Crowthorne on 13th October 2009. Members of the GripTester for roads User Group were invited to attend and eleven GripTesters participated. Skid resistance was measured by all machines, each having their own dedicated tow vehicle and crew, on sections of the TRL test track and on sections of local in-service roads. This report summarises the analysis of skid resistance results, and details the comparisons made between GripTesters, as well as estimates for the repeatability and reproducibility of the fleet.
In addition, two SCRIM (sideway force coefficient routine investigation machine) vehicles were invited to attend, and skid resistance was measured using these devices on the same surfaces. A correlation between mean SCRIM Coefficient and GripNumber has been calculated and is presented in this report.
As part of an ongoing commitment to improving the standing of the GripTester leading towards formal accreditation, recommendations for future trials are made.

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