Roads remain slipperyeven with anti-skid seal

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    SYRENE KOON

    Even though cars and trucks slid all over I-80 Nov. 15 as they crossed Parley’s Canyon, it was not because the road was missing a final plantmix seal, which improves drainage, traction and preserves the underlying layer, said Stan Burns, operations engineer for region two of the Utah Department of Transportation.

    “The department has a machine that checks skid resistance and this stretch of highway is adequate,” Burns said. “The machine drives down the road, applies water, simulates the braking action of a vehicle and then numbers are generated to measure the skid resistance.”

    Burns said that although the plantmix seal, which is applied to overused highways, improves traction and lessens skidding, it does not affect the road conditions.

    “Testing the skid resistance depends on the type of road you are dealing with, said Tracy Conti, planning statistics engineer for UDOT. Roads are scored by a numbering system. If the road is marked above 45 it’s OK to drive on, but anything below 35 is marked as slippery when wet, Conti said.

    Parley’s Canyon data showed that eastbound I-80 scored an average of 53 and westbound averaged 55.5.

    “In this case, a plantmix seal coat won’t change skid resistance too much, Conti said. “Sixty is as high as you are going to get.”

    It used to be a common practice to wait a year before applying the final sealing coat because there was better adherence when a plantmix seal was put on. Not having this final coat is not dangerous to drivers and does not drastically affect driving conditions, Conti said.

    The Utah Department of Transportation plans to improve winter-driving conditions by installing a new electric message board which will notify drivers of existing road conditions and warn them to install chains or turn around. Violators of the warning will be ticketed. There is currently a sign that merely posts when chains are required.

    An area at the base of Parley’s canyon directs drivers to a paved area where they can put on chains before driving up the canyon.

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