Dry Pavement Friction Reductions Due to Sanding Applications

Duane R. Meyers; Timothy P. Austin

doi:10.4271/2012-01-0603

The importance of friction applications in the field of collision reconstruction is well recognized in published research. However, tire-road frictional drag values (μ-values) are partially dependent on the surface on which the tire is travelling. One such variable may be the intentional presence of sand upon a particular roadway. Sand is sometimes applied to dry pavement in an effort to absorb liquid debris that may have been accidentally spilled onto the surface. Once the sand has been applied, it may be left for a measureable time until the fluid has been absorbed. If a collision were to occur on that particular surface while the sand is in place, it may be difficult to determine an appropriate μ-value for the given scenario.

In an attempt to examine the extent of friction reduction for both a passenger vehicle and a commercial truck on such a surface, testing was performed in a like condition. For both vehicle types, full braking with an active Anti-Lock Brake System (ABS) was used to measure the respective average and dynamic μ-values. For the testing, a 2006 Freightliner Century Class tractor pulling a fully loaded semi-trailer was compared with a 2007 Ford Crown Victoria automobile.

Test conditions consisted of a baseline dry asphalt surface, a surface of loose sand, a surface of packed sand, and finally a surface whereon there was a residual amount of sand. During the test runs, the vehicles were instrumented with recording devices to measure the relative acceleration and test speeds. In performing these tests, it was found that the application of sand did reduce the pavement friction as suggested in prior research concerning similarly covered road surfaces. However, it was also found that while the performance results varied significantly between the tractor semi-trailer and the passenger vehicle on dry pavement, their net braking abilities were much closer after the sand was applied.

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Dry Pavement Friction Reductions Due to Sanding Applications 2012-01-0603

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