Implementation and Evaluation of RWIS ESS Siting Guide

This report summarizes the effort initiated by FHWA in 2007 to update the "Road Weather Information System Environmental Sensor Station Siting Guide", published in 2004. A stakeholder process was conducted in order to document experience with implementation of the ESS Siting Guidelines. An initial phone outreach was conducted to nine DOTs. Most of these agencies have extensive RWIS, although most of the systems were implemented prior to issuance of the Guidelines. Three states: Michigan, New Hampshire and Idaho, were selected for site visits and in-depth interviews. The suggested revisions to the Guidelines are based on input from both phases of the stakeholder process. Those familiar with the guidelines generally provided positive feedback. The consensus was that the Guidelines covered most of the major issues in the siting of ESS and provided the necessary information in a concise manner. Knowing that there would be a number of recommended additions to the Guide, one important objective identified early in the process was to maintain the Guidelines as a concise and accessible document that stayed focused on the deployment of ESS. The major change made to the Guide involved the metadata table that was included in the original report. Since the original Guidelines were developed a major effort was conducted as part of the Clarus project do define a standard set of metadata for ESS. An expanded metadata table was thus included in the Guidelines showing Clarus metadata in three categories: required, recommended and optional. The metadata requirements defined for Clarus were quite extensive and may not be realistic for all ESS installations. Some items in the recommended and optional categories were highlighted as not being critical for most DOT requirements. Overall a very limited number of changes were recommended for the guidelines document. Other than the modification to the metadata table, most of the additions were limited, and designed to highlight areas of concern noted by DOTs with ESS experience. It is the case that many agencies are deploying other ITS technologies with ESS; however it was felt that this could greatly expand the document and result in a loss of focus on ESS technology. The feedback from most of the DOTs interviewed was positive and they expressed an interest in using the document for future deployments. Several noted that they would require their contractors to use it.