Urban transportation planning evolved from highway and transit planning activities in the 1930s and 1940s. These efforts were primarily intended to improve the design and operation of individual transportation facilities. The focus was on upgrading and expanding facilities. Early urban transportation planning studies were primarily systems oriented, with a 20-year time horizon and regionwide in scope. This was largely the result of legislation for the National System of Interstate and Defense Highways, which required that these major highways be designed for traffic projected 20 years into the future. As a result, the focus of the planning process through the decade of the 1960s was on this long-range time horizon and broad regional scale.
Gradually, starting in the early 1970s, planning processes turned their attention to shorter-term time horizons and the corridor-level scale. This came about as the result of a realization that long-range planning had been dominated by concern for major regional highway and transit facilities, with only minor attention being paid to lesser facilities, and the opportunity to improve the efficiency of the existing system. This shift was reinforced by the increasing difficulties and cost in constructing new facilities, growing environmental concerns, and the Arab oil embargo.
Early efforts with programs such as TOPICS and express bus priorities eventually broadened into the strategy of transportation system management. TSM encompassed a whole range of techniques to increase the utilization and productivity of existing vehicles and facilities. It shifted the emphasis from facility expansion to provision of transportation service. The federal government took the lead in pressing for changes that would produce greater attention to TSM. At first, there was considerable resistance. Neither institutions nor techniques were immediately able to address TSM options. A period of learning and ad-