Abstract
The literature concerning the design and the effects of acoustical and optical warning devices for emergency vehicles was reviewed. The available results do not indicate a single clear-cut, "optimal", signalling device, but can at least be interpreted as indicating some possibilities for improvement of the present system. Due to some inherent disadvantages with conventional sound and light signalling it is suggested that, in order to obtain any major effects on the safety and effectiveness of emergency vehicles, some new measures and solutions should be considered. (A)