Mobile devices measuring skid resistance

A substantial number of mobile devices for measuring surface skid resistance have been developed globally. The majority of them have been manufactured in European Union (EU) countries. A relevant EU survey identified and reported 21 mobile devices (TYROSAFE 2008). Table 16.5 presents 19 of those devices together with their basic characteristic features. 

The most popular friction devices according to the TYROSAFE report are the SCRIM (used by nine EU countries) and the GripTester, towed device (used by eight EU countries). Two EU countries use the Skiddometer BVll and two EU countries use the SRM (Stuttgarter Reibungsmesser) or RoadSTAR (Road Surface Tester of Arsenal Research). All other devices are used by only one EU country (TYROSAFE 2008). An overview of highway and runway friction devices is also provided by NCFIRP web-only document 108 (Hall et al. 2009). 

Another popular device is the ASTM skid trailer (towed device), known as ASTM skiddometer. 

Apart from the abovementioned devices, there are also the following skid resistance measuring devices the Japanese Skid Tester (locked wheel type operating speed during measurements, 30-90 km/h), DBV of NASA (locked wheel type operating speed, usually 65 km/h), Komatsu Skid Tester (Japan) (fixed slip ratio type between 10% and 30% slip ratio, operating speed between 30 and 60 km/h) and SRT-3 (Japan) (locked wheel type operating speed between 30 and 90 km/h). More information is provided in NCHRP (2000). 

Other devices to be mentioned are the Mu-meter (United Kingdom) (fixed slip ratio type 13% or 7.5% operating speed between 20 and 80 km/h) and the Runway Friction Tester (United States) (fixed slip ratio type 15% operating speed between 30 and 91 km/h). These devices have initially been developed for runway skid resistance measurements. 

---

Surface skid resistance is measured by self-powered mobile devices or towed mobile devices. Spot measurements or measurements over short road sections are usually carried out by the British pendulum or ether portable devices. 

The mobile devices are distinguished into two categories. The first category includes devices where the skid resistance is measured by an independent wheel moving at zero angles to the direction of travel. Measurements are taken while the wheel is fully locked (blocked). 

Other portable-push devices were developed for skid resistance measurements in areas with certain restrictions, such as road markings, or in general where the skid resistance measurements with mobile devices are not possible. 

---