Accelerated Pavement Testing (APT)

Accelerated pavement testing (APT) refers to “the controlled application of a prototype wheel loading, at or above the appropriate legal load limit to a prototype or actual, layered, structural pavement system to determine pavement response and performance under a controlled, accelerated accumulation of damage in a compressed time period” (Metcalf, 1996[1]). Typically APT involves (1) a specially designed test track like those at Mn/ROAD, WesTrack and NCAT where actual trucks are driven across prepared pavement sections, or (2) a specially designed loading mechanism that can provide simulated loads on an existing or specially built pavement section such as Caltrans’ heavy vehicle simulator.

Test Tracks

Test tracks are used for full-scale pavement testing.  Typically, a test track is round or oval in shape and uses either manned or unmanned test trucks to apply loads, although the FHWA’s Pavement Testing Facility (PTF) uses two Accelerated Load Facility (ALF) machines, which are mechanical arms that move full-sized tires around in a circular pattern.  Regardless of the particular setup, test tracks are used to apply large amounts of heavy loads to a single pavement section in a relatively short period of time.

Heavy Vehicle Simulator (HVS)

The heavy vehicle simulator (HVS) is a mobile linear loading device that applies loads to small sample areas on full-scale pavements.  Essentially, it is parked over the pavement section to be tested and then a wheel loaded to a predetermined amount is lowered and run back and forth across.  The mobility of the HVS allows for accelerated pavement testing of in-use pavements almost anywhere safety will allow.

Caltrans HVS.
Figure 1. Caltrans HVS.

Caltrans HVS at Ukiah, CA.
Figure 2. Caltrans HVS at Ukiah, CA.

Caltrans HVS.
Figure 3. Caltrans HVS.

Caltrans HVS at Richmond Field Station.
Figure 4. Caltrans HVS at Richmond Field Station.

Footnotes    (↵ returns to text)
  1. Metcalf, J. B. NCHRP Synthesis of Highway Practice 235: Application of Full-Scale Accelerated Pavement Testing. TRB, National Research Council, Washington D.C., 1996