Increased damage to uphill rigid pavements from full-trailers

الملخص EN

Design charts for truck equivalence factors for full-trailer on uphill rigid pavements were developed for a terminal level of serviceability pt = 2.5.

Each chart is devoted to a certain rigid pavement slab thickness giving the truck equivalence factor versus the total weight of the full-trailer for an uphill gradient of 0, 6, 12 and 18% as well as a certain ratio of the height of center of gravity of each unit of the full-trailer to the corresponding wheel base (H / B).

Five values for slab thickness were considered namely D = 6, 8, 10, 12, and 14 inches (15.2, 20.3, 25.4, 30.5, 35.6 cm respectively) and one value for H / B ratio of 1.0 were used.

Due to axle load redistribution on upgrades, the axle loads for the full-trailers were calculated assuming uniform motion and taking into account the effect of the moment of the component of the weight of the tractor and trailer unit parallel to the upgrade and acting at the center of gravity of each unit .A strong linear correlation between the rolling resistance and total weight of the trailer unit was obtained to arrive at the pull force in the rod when travelling on uphill pavements.

The paper reveals the significant effect of the upgrade magnitude as well as of the H / B ratio on the truck equivalence factor.

The truck equivalence factors increase non-linearly with increasing truck weight, H / B ratio and upgrade magnitude.

This increase is quite significant for the higher values of upgrade, H / B ratio as well as the slab thickness.

The critical full-trailer is that having a total weight exceeding about 400 kN beyond which the corresponding equivalency factor on uphill pavement diverges significantly from that on level highway.