Falling weight deflectometer (FWD) and truck tests have beenconducted on the Minnesota Road Research project (Mn/ROAD) inan effort to (1) study truck speed effects on flexible pavements,(2) compare pavement response under FWD and truck loads; and (3)investigate the effects of wheel path offset on the pavement response.

Three flexible pavement sections were used for this study.The truck tests were performed at various speeds ranging from10 to 103 km/h.

The results showed that on a smooth pavement (IRI=O.97 m/km)strains in the bottom of the pavement continuously reduced withthe truck speed. While on a relatively (relative to the smoothpavement) rough pavement (IRI=l.74 m/km), strains in the bottomof the pavement decreased as the speed of the truck increasedto a speed about 65 km/h, but the strains increased when the speedwas further increased from 65 km/h to 103 km/h. The effects ofthe pavement surface roughness were also investigated and theinfluence of truck suspension type was discussed.