Abstract
This paper proposes some solutions regarding planning criteria for transport infrastructures: in central urban areas it is first necessary to determine a system of main frames of traffic according to a precise hierarchy of modal alternatives, compatible with the available resources, the building times, and particular morphologies and settlements, considering also the most unfavorable of the local components. Japanese Ministry of Construction and OECD/Road Transport Research Programme held the seminar on "future road transport systems and infrastructures in urban areas" in Chiba, Japan on 4th - 6th june 1991 sponsored by the Japanese organizing committee.