ROAD WEATHER INFORMATION SYSTEM ENVIRONMENTAL SENSOR STATION SITING GUIDELINES

A Road Weather Information System (RWIS) consists of the hardware, software, and communications interfaces necessary to collect and transfer road weather observations from or near the roadway to a display device at the user's location. While the original purpose of RWIS was to address winter weather conditions, applications have been developed to detect and monitor a variety of road weather conditions impacting road operations and maintenance. Most RWISs now consist of several meteorological and pavement condition monitoring stations strategically located near highways to help transportation managers make more informed operational decisions. An Environmental Sensor Station (ESS) is considered the "collection" component of an RWIS and consists of the equipment and sensors installed within or along a roadway. This document provides guidelines for siting an RWIS ESS and its associated environmental and pavement sensors. These guidelines are intended to help establish uniformity in siting ESSs and to improve the usefulness of road weather information derived from ESS observations. The document provides siting criteria that satisfy as many road weather monitoring, detection, and prediction requirements as possible. The siting criteria are based on an analysis of published documents on the siting of weather and pavement sensors, and the results of interviews with nearly two dozen road weather experts representing state departments of transportation, equipment suppliers, and consultants. The recommendations encourage uniformity in ESS siting and in the application of the road weather observations. Many of the recommended criteria include a range of values. These values reflect both the complexity of the roadway environment and the need for additional research. The guidelines recommend that siting decisions be made by a team of transportation operations, road maintenance, and weather experts. The siting guidelines contained in this document do not represent standards for agencies or vendors to follow, but rather a set of recommendations to consider.