A push-button call-box system was installed on an 11-mile section of i-45 in Houston. The system is composed of 65 master and 80 secondary boxes spaced at 1/4-mile intervals on the freeway and a receiving console located at the Houston police department. Stranded motorists may send requests for 4 types of aid: police, ambulance, fire, and service. Use data for a 6-month period were collated. During this period 1,025 calls were placed for a daily average of 5.6 calls and a use rate of 6.3 calls per million vehicle-miles. Rate of use of a given box was found to be a function of the distance to alternate assistance. One-third of the calling motorists had left the scene before service arrived. Use and driver interview data indicated that driver understanding and acceptance of the system were not complete. More than one-third of the disabled motorists were not aware of the system, while another one-third indicated that they did not use the system because of the costs ($6.00 to $18.50, depending on service required) involved when requesting service. /author/
Samenvatting