Eric Ferguson - Travel Demand Management and Public Policy

What is the solution to the problem of traffic congestion? Because I am an academic who works in the field of transportation, that is the question I am most often asked. It comes up at cocktail parties when strangers learn of my work. It is also the most common inquiry of newspaper and television reporters, who seem always to call when I have little or no time to talk with them. The same question is often posed to me as a potential topic for a luncheon talk to civic associations. Why is everyone so terribly concerned about traffic congestion, while Fm not really even sure that traffic congestion is a problem needing to be solved? Traffic arises from economie growth and social activity, and it must be better to suffer the consequences of congestion than to have empty roads and the conditions that might cause them. On the other hand, it is probably obvious that we want to have our cake and eat it too. We want economie growth, suburban development, personal vehicles, cheap gas, good public transit, clean air and less traffic congestion. Now how do we accomplishthat?

The truth is that there is no one solution to traffic congestion. Congestion is a complex phenomenon that arises under different circumstances and at different times for different reasons. In some situations a doubling of trips to an area can cause no measurable increase in delay; in other cases the addition of a few cars to the traffic stream can cause a dramatic slowing in travel speeds. Furthermore, almost every clich about traffic is wrong. While it is today commonly said that we cant build our way out of traffic congestion, there are innumerable instances in which adding new capacity is the most cost effective way to ease congestion. But, there are other situations in which adding new road capacity could worsen rather than improve traffic congestion. It is equally wrong to think that public transit investments are always more equitable or always more environmentally benign than highways, though they sometimes can be. Similarly, some dismiss travel demand management as inherently inadequate or inconsequentiala small, perhaps politically correct, fix for a big problem. Some say that employer trip reduction programs failed, but the truth is that some programs failed, some succeeded, some were costly and others were incredibly cost effective. Some were popular and some unpopular. Most were popular among certain constituencies and hated by others. The truth is that there are no simple solutions and that there are few obvious truths.

Travel demand management is a phrase in increasing use since the energy crisis and the elevation of air quality to a centrai theme in transportation policymaking. TDM refers to those elements of transportation policy that attempt to marginally change travelers behavior so as to use the transportation system more efficiently. Can we encourage people to double up and triple up when roads are most congested, or to park their cars and ride public transit in corridore where congestion is endemie? Can policies encourage people to shift the times of their trips from peak travel hours to less congested times or to occasionally bike to work? TDM is not a substitute for other transportation policies. It can easily be combined with investments in public transit systems or new highways in order to attempt to make our investments in those systems more cost-efficient. TDM is included in air quality management plans for environmental reasons, and in regional transportation plans for reasons of cost-effectiveness. While TDM can be a low technology approach in comparison with automated people movers, it can also be a centrai element of new investments in traffic management systems that try to affect traffic flows by providing travelers with more accurate and more timely information on current traffic conditions and on a wide variety of travel alternatives.