The effect of reduced tire pressure on sediment production from a forest road

Bellitto, M.; Burroughs, E.R. Jr.; Foltz, R.B. 1991. The effect of reduced tire pressure on sediment production from a forest road. A report on a cooperative study between the Intermountain Research Station, WO Engineering and San Dimas Technology and Development Center. Internal Document. 28 p.

Keywords: tire pressure

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Abstract: Two 100-ft forest road section (plots) were bladed and used to measure sediment production from a loaded logging truck using normal (95 psi) tire pressure on one section and reduced (70 psi for steering axle and 50 psi elsewhere) tire pressure on the other. Each insloped road plot was divided lengthwise into two subplots 100 feet long by 5.7 feet wide to define one wheel track. Three simulated rainstorms at a rate of 2 inches per hour for 30 minutes each were applied to each plot before truck travel and three more were applied after truck travel. Increases in sediment production (kg) from the normal tire pressure plot ranged from +8% (dry run) to +121% (wet run) for the three rainfall applications, with an average value of +67%, compared to the reduced tire pressure plot. Increases in sediment concentration from the normal tire pressure plot ranged from +32% (dry run) to +132% (very wet run) for the three rainfall applications, with an average value of +74%, compared to the reduced tire pressure plot. These increases in sediment production and sediment concentration were caused by more concentrated flow, with more erosive power, in the deeper ruts formed in the normal tire pressure plot. Soil moisture contents for 3 of the 4 subplots were greater than the optimum for compaction, but the higher ground pressures on the normal tire pressure plot caused significant rutting while the road surface of the reduced tire pressure plot had only minor ruts. These tests clearly indicate that the use of VTP has a significant potential to reduce adverse impcts on water quality.

Moscow FSL publication no. 1991h