AASHTO T 242-18 PDF Download

AASHTO T 242-18 is a standard method that outlines the procedure for measuring the frictional properties of paved surfaces using a full-scale tire. The objective of this method is to determine the steady-state friction force on a locked test wheel as it is dragged over a wetted-pavement surface, under constant load and at a constant speed. The major plane of the tire is positioned parallel to the direction of motion and perpendicular to the pavement.

It is important to note that the measurements obtained from this method represent the frictional properties specific to the equipment and procedures described in the standard. These values may not directly correlate with those obtained through other pavement friction measuring methods. The purpose of these measurements is to compare certain frictional properties of a pavement relative to other pavements or to evaluate changes in frictional properties over time.

However, it is emphasized that the values obtained from this method are insufficient for determining the stopping distance of a vehicle on both wet and dry pavements. Additionally, they are not sufficient for determining the speed at which control of a vehicle would be lost. For those determinations, peak and side-force friction measurements are required.

It is worth mentioning that the majority of the test method described in AASHTO T 242-18 is identical to ASTM E274/E274M-15, except for a subsection regarding steel grated bridge decks and terminology.