the perceived positive impact of transportation investment on eco- nomic development is one of the most important considerations to transportation decision makers. Given the importance of metropolitan areas as economic engines of national economies (see Sec. 12 and [Armstrong. 1999 providing an efficient, urban transportation system is a necessary precursor for a healthy economy .
As previously noted, however, the major economic benefit for well-established urban economies is likely to be productivity gains rather than growth in jobs. In most cases, transportation investment by itself is not likely to cause significant change in economic activity.
Supportive market forces and public policies are also important to spur economic development