Voluntary TDM efforts work well in dealing with short term problems, but promise few long term gains. Market mechanisms often promise the exact opposite effect. Short run price elasticities are low in transportation. This may be because there are few good alternatives available, people are comfortable with their current choices, or both. Long run price elasticities are usually much higher. This is because markets have more time to sort things out by developing and implementing new and improved transportation alternatives. Over time, people’s lives change in many ways, some of which may facilitate concomitant changes in travel behavior. On average, most people change jobs every tour or five years and residences every six or seven years. This occurs even during the stability of middle age, when mamtaining the status quo can be important for child rearing purposes.