ICC's Model SFT5041 and SFT5042 Pavement Skid Friction Test Systems measure the average coefficient of a paved surface in accordance with ASTM E274, and measure the peak or incipient slip friction of a paved surface in accordance with ASTM E1337. The information collected with the test system helps determine changes in surface friction due to deterioration, weathering, or other characteristics. These systems consist of a specially equipped pickup truck and a specially equipped towed two-wheeled trailer.


The skid truck contains a water system which supplies water to the test operations, electrical equipment to supply the required DC and AC power to the test system, and a computer system to activate tests and record the measured data. In typical testing, the driver of the truck maintains the desired test speed then activates a test where the equipment:
 

	Dispenses water at the trailer wheel.
	Actuates the trailer braking system to lock up the wheel.
	Detects the resultant wheel traction force, wheel load and vehicle speed.
	Uses the resulting force time information to determine the friction of pavement for the standard test tire. The friction value detected is reported in real time and is saved on disk for future use.

The skid trailer uses an ASTM standard ribbed or blank test tire. The trailer can be pulled over a paved surface by the truck at a constant velocity while a nozzle dispenses water in front of the tire to simulate wet conditions.

The test wheel of the trailer is coupled by a disc brake assembly to a calibrated force transducer, which measures the traction force and load on the wheel under braking. The electrical/mechanical devices in the trailer are controlled by the computer system electronics in the pickup truck in combination with switches on an operator's control console.

	DOT's use the information to help determine if a paved surface needs resurfacing or rehabilitation.
	Airports determine if runways have adequate friction values.
	Tire manufacturers use it to help test characteristics of new products.
	It is used in a court of law to determine if safe roadway conditions are present.