This document describes the implementation and evaluation of the existing Road Weather Information System (RWIS) Environmental Sensor Station (ESS) Siting Guidelines (Guide) and the recommended enhancements. The Guide was originally released in 2004 by the Federal Highway Administration (FHWA) in cooperation with the American Association of State Highway and Transportation Officials (AASHTO) Snow and Ice Cooperative Program (SICOP), and the Aurora Pooled Fund Program as a means of documenting best practices in RWIS ESS deployment. Potential changes in the Guide are driven by lessons learned from agencies using the Guide for ESS deployments and other road weather applications that seek to expand the availability and application of environmental information.
As part of the evaluation, State Departments of Transportation (DOTs) that have recently deployed ESSs were surveyed for their familiarity with, and experience using the Guide in those deployments. The Guide was reviewed in light of the DOT experience, other road weather management strategies, and systems engineering principles to identify potential areas for improvement. In addition, three State DOTs—Michigan, Idaho, and New Hampshire—provided more detailed insights on the impacts of the Guide on their ESS deployment experience. In the case of Michigan, evaluation of the Guide was provided as part oftheir deployment planning and design. Recommendations for revising and enhancing the Guide were derived from the review process.
Additional recommendations for the collection and management of RWIS ESS metadata are also included in this evaluation. This metadata is essential to ESS life cycle management and expands the usefulness of the ESS observations to the meteorological and transportation communities.
Recommendations accepted for inclusion in a subsequent revision of the Guide include
- Changing the title of the document itself to Road Weather Information System (RWIS) Environmental Sensor Station (ESS) Siting Guide
- Discussion of the use of the Guide and its systems engineering fit with the National ITS Architecture
- Use of examples to illustrate particular guidelines
- Enhanced discussion of siting ESS in conjunction with other ITS components
- Pointing to manufacturer recommendations for siting criteria specific to particular sensors
- Updating guidelines for ESS metadata
