Road surface conditions, particularly ice and snow, are not a permanent feature of the roadway. This lack of permanence in hazard formation, location, and duration makes effective signing difficult. To compensate for this difficulty in predicting ice warning signing requirements, two practices have emerged: oversigning and standard sign placement. The purpose of the project was to provide (1) insight into the effectiveness of current ice warning signing placement practices based on other state practices, ice-related accident locations and frequencies, and public attitudes toward the warning signs; (2) insight into driver behavior related to ice warning signs based on public response and observed driver behavior; and (3) possible recommendations for ice-related accident "trouble spots" not currently signed.
The research approach comprised four primary tasks: (1) conducting a national review to learn of previous ice warning sign experiences, (2) identifying current placement practices for ice warning signs in Washington, (3) considering public attitudes about and responsiveness to Washington's ice warning signs, and (4) examining problems related to public safety and state liability in Washington.
On the basis of positive public support for ice warning signs, WSDOT's perceived liability in the event of an ice warning sign accident, and the terms required to escape or minimize liability damages (i.e.. proof of a reasonable and systematic process for placing signs), the continued use of ice warning signs is recommended. However, signs should be placed not at standard, sometimes irrelevant locations (e.g., entrances to state routes) but rather at high-risk areas (e.g. at bridges or locations identified by motorists) or locations with a history of ice-related accidents.