Characteristics of motorist aid communications systems

The nature and magnitude of the demand for emergency communications generated by users of rural freeways is described. A classification diagram of potential communications systems is presented and a preliminary selection of candidate systems is made on the basis of overall technical and economic considerations. The operating efficiency of the selected systems is analyzed in terms of their estimated detection efficiency and detection time performance. This analysis when combined with system cost projections demonstrates that a one-mile interval terminal design providing two-way voice communication between the motorist and an aid dispatch center provides the best benefit-cost ratio consistent with a satisfactory level of service. The operational characteristics of the selected system are described in some detail.