Construction activities can induce soil compaction due the use of heavy vehicles and repeated vehicle passes. Driving on access material reduces the risk of compaction, but data on soil stress reduction are lacking. This study investigated the effect of three access materials (0.5 m thick sand track, 0.3 m thick timber mattresses, and 0.1 m thick composite mats) on soil stress, relative to driving on unprotected soil. Mean normal stress was measured at 0.2 and 0.4 m soil depths for tracked and tyred construction vehicles (bulldozer, excavator, dump truck, and tractor-trailer). We used finite element modelling to investigate the effect of material’s thickness and stiffness on soil stress reduction. Measurements revealed that driving on access material reduced soil stress by 21–77 % and 0–60 % at 0.2 and 0.4 m depths, respectively. Stress reduction increased with increasing mean ground pressure and was larger for tyred than for tracked vehicles. The tested access materials reached a comparable effect, but simulations indicated that additional stress reduction could be achieved by increasing the stiffness or thickness of the material. Thus, more rigid or thicker material achieve greater soil stress reductions. These characteristics should be balanced against costs, transport, and ease of handling of the material.