This article reports on a study examining the use and effectiveness of static signs warning drivers of non-permanent hazards. These warning signs are frequently used for occasional hazards such as wildlife crossings, falling rocks and icy bridges. A literature review was conducted and a survey was sent to state departments of transportation to review the current use of static warning signs for occasional hazards (SWSOH) and whether any research documents the effectiveness of these signs. The literature reviewrevealed that there is a lack of distinction in the literature between warning signs for permanent potential hazards(curves, winding roads etc.) versus those for occasional hazards. Most studies investigating the effectiveness of SWSOH were conducted in comparison to unconventional or enhanced warning devices. The survey showed that most agencies had not done any evaluations of the effectiveness of SWSOH, but that most perceived that SWSOH were only somewhat effective. The criteria for the installation of SWSOH appear to be vague and arbitrary, largely relying on engineering judgment. About 20% of respondents considered tort liability and litigation as having an important role in the decision to use SWSOH. More than half of responding agencies reported using unconventional warning devices, such as static signs with flashing lights, and most considered these unconventional warning devices to be effective. The findings from this study highlightthe need for more research to establish the effectiveness of various warning devices for occasional hazards.
Abstract