A state-of-the-art report was prepared on adaptive speed limit signs; that is, intelligent signs displaying variable speed limits based on weather or traffic conditions. A review of the international literature was undertaken, and an international conference was attended in Europe, where first hand knowledge was gained on this application of IVHS (intelligent vehicle highway systems) technology. It was found that adaptive speed limit signs are in use on freeways in several countries, notably the USA, Germany, and Taiwan, on a pilot basis at this stage. Several other countries may also have pilot installations, or are considering that option for sites where fog or ice are prevalent, or where traffic congestion is likely to arise from incidents. A sample specification was prepared for an Australian pilot project, to trial and demonstrate the technology.