Locked wheel friction testers measure pavement friction accurately and directly. The tire on a specialized trailer skids over wet pavement The friction coefficient is calculated between a tire on the specialized trailer as it skids over wet pavement. The truck carries a water tank and control system. The system:
- Measures the average friction coefficient in accordance with ASTM E274
- Measures the peak or incipient slip friction in accordance with ASTM E1337
- Identifies changes in surface friction due to deterioration, weathering, or other characteristics
The collected data is used to:
- Determine if a paved surface needs resurfacing or rehabilitation
- Test characteristics of new surface treatments, such as high friction treatments
- Determine if roadways, intersections, and crosswalks have safe friction levels
- Determine if runways have adequate friction values to meet airport specifications
Reduced pavement friction causes accidents and vehicle departures from the roadway. Often, sections of road with poor friction can be repaired by applying high friction surface treatments (HFST). Friction testing is an important tool departments of transportation use to identify safety problems and thereby to avoid accidents – and costly legal claims.
The trailer is available in single- and dual-sided versions. The single-sided trailer applies the water and braking force on one side only, whereas the dual-sided unit alternates between the two sides to measure friction in both wheelpaths.
System consists of a specially equipped truck and trailer that collects accurate surface friction data. The truck has a 300 to 400 gallon water tank, depending on the type of truck chosen. The system meets the requirements of ASTM E274 and ASTM E1337.
The Extended Range system collects accurate friction data for extremely long distances. The system can hold up to 1200 gallons of water which results in a 400% increase in productivity.