United States Department of Agriculture Engineering Forest Service Technology & Tech Tips Development Program April 1995 7700 9577 1330--SDTDC CENTRAL TIRE INFLATION (CTI) REDUCES SEDIMENT UP TO 84% A METHOD TO HELP MEET NEW WATER QUALITY STANDARDS & GUIDELINES Tom Moore, CTI Project Leader, SDTDC Randy B. Foltz Ph.D., Research Engineer, INT Larry Cronenwett, Transportation Planning & Analysis Groop Leader, Region 6 Research studies conducted over the last five years The Boise National Forest recently sold a 12 mmbf indicate that dramatic reductions in sediment from timber sale with requirements for reduced pressure road surfaces can be expected by using lower tire on log truck and heavy truck traffic. The primary pressures on heavy-haul vehicles. The roads with reason for this requirement is to reduce sediment the most dramatic reductions in road surface sediment into streamcourses and protect the resident Bull are those with no surfacing material, or surfaced Trout population. with aggregates that produce a high degree of fine material during hauling operations. The use of on-board Central Tire inflation (CTI) systems on heavy-haul vehicles Research conducted in Lowell, Oregon concluded facilitates the raising and lowering of that reducing tire pressures on heavy-haul pressures while the vehicle is in motion. vehicles reduced road surface sediment In addition to increasing interest by an average of 80% over a three year the Forest Service in the use of CTI test period on a forest road surfaced systems for hauling of National Forest with an aggregate producing a products, several private timber large amount of fine material during corporations are currently using the hauling. One test year noted system, or proposing the use of the reductions in sediment levels of system, to help control sediment 84%. Tire pressures were lowered production. from highway pressures of 90 psi to 30 psi in the drive tires while The expected reductions in road empty, and to 50 psi in the drive surface sediment will vary and trailer tires when fully loaded. depending upon site conditions Speeds were less than 35 mph. such as precipitation, composition of the road surface, traffic levels, This research has major implications and other factors. However, the to National Forests, and other forested underlying principles responsible areas, that administer watersheds for the reduced sediment, requiring higher water quality standards. shallower ruts and less For example, the recently published concentrated flow, would be expected standards and guidelines amending National Forest to produce similar results in other locations. An effort Plans in the Columbia River Basin imposing stringent is currently underway by the Intermountain Research measures to reduce sediment levels. These new Station and the San Dimas Technology and Development standards and guidelines are required to protect and Center to develop guidelines quantifying the expected improve vital spawning habitat for dwindling supplies reductions in road surface sediment for various situations of native Coho and Chinook Salmon. and areas around the country. (CTI is a commercially available electromechanical device that allows the driver to raise and lower tire pressures while the vehicle is in motion.) ------------------------------------------------------------------------------------------------------------------- For additional information contact: Paul Greenfield, Program Leader--Roads, San Dimas Technology & Development Center. 444 E. Bonito Ave., San Dimas, CA 91773 Phone: 909-599-1267 FTS: 700-793-8225: FAX. 909-599-2309: DG-P.Greenfield:W07A