Question 4a: characteristics of highways and motorways as a function of the traffic. Question 4b: highways and motorways in rural areas: equipment/operation.

Twenty one countries have submitted reports on the themes covered by question 4. Some countries deal with the complete subject of question 4, others concentrate their report on a selection of points. The general report takes up the essential points of the different national reports, underlining the divergent and/or novel points of the problems treated. A review of the general report may be found in the journal "revue generale des routes", no 519, april, 1976. For the covering abstract, see IRRD abstract no 104484.