Impact of tridem and trunnion axle groups on premature damage of pavement infrastructure

To make appropriate decisions on overload limits of various axle configurations that can be endorsed for routine permitting, highway agencies need to understand the impact of these axle groups in terms of pavement infrastructure damage. This paper examines the relative damage to pavements induced by tridem and trunnion axle groups. The analysis was conducted with typical structures of both flexible and rigid pavements by first analyzing the mechanistic responses of pavements to tridem and trunnion axle groups. Then the mechanistic responses were used as the input to performance-based fatigue models to quantify the relative accumulative damage to the pavements. The use of the performance-based fatigue models ensured that all types of damage (such as rutting and cracking) induced by the axle groups were taken into consideration. Based on the analysis results, it was found that for flexible pavements, tridem axle groups are more damaging than trunnion axle groups, whereas for rigid pavements, trunnion axle groups are more damaging than tridem axle groups.Key words: trunnion, tridem, load equivalency, pavement damage.