Road Weather Management Program - FHWA Operations - U.S. ...

Best Practices for Road Weather ManagementVersion 3.0Colorado DOT Variable Speed Management SystemColorado State Highway 82, in Snowmass Canyon (between Aspen, CO and GlenwoodSprings, CO) is composed of an elevated southbound roadway that shades the northboundroadway during certain times of the day causing rapidly changing freezing conditions. TheColorado Department of Transportation (CDOT) installed the Variable Speed ManagementSystem which consists of a complete Road Weather Information System (RWIS), using newlydeveloped non-intrusive pavement weather sensor technology. The pavement sensors monitortraction/friction conditions in the area that is shaded, and allow for alerts when conditionswarrant. The system is capable of monitoring wet conditions, wet conditions with traction lossas freezing begins, and snow and ice conditions. The system wirelessly communicates to asingle variable message sign (VMS) and a single variable speed sign (VSS) that are locatednearly a mile in advance of this northbound section of highway in Snowmass Canyon (seeFigures CO-3 and CO-4).Figure CO-3. RWISSnowmass Canyon.Figure CO-4. Alert of wet roads.System Components: The system consists of the following major components:• Variable Message Sign• Road Weather Information System (RWIS), which consists of the following:o Remote Processor Unito Non-Intrusive Surface State Sensoro Non-Intrusive Surface Temperature Sensoro Air Temperature/Relative Humidity Sensoro Precipitation Identifier and Visibility Sensoro Ultrasonic Wind Sensoro Pan-Tilt-Zoom Color Camerao Relay Device Controlo Wireless Device Control27