Some TDM measures have been in use for years, such as the promotion of carpooling, which began during World War II. Broader implementation of TDM began during the 1970s and 1980s, often stimulated by problems related to our heavy reliance on foreign energy sources. More recently, increasing congestion, decreasing state and federal transportation funding, and concerns over related issues such as air quality have resulted in increasing attention to TDM as an alternative to building more roads and highways.

TDM and Commute Trip Reduction (CTR) Legislation

Have you ever noticed that most of the automobiles on our highways have only one person in them, and that's the driver! As more and more people begin to drive, we are beginning to see an increase in air pollution and traffic congestion. The Washington State Legislature is aware of these two problems, and in an effort to reduce air pollution, traffic congestion and energy consumption, they passed the Commute Trip Reduction (CTR) Law. This law is a Transportation Demand Management (TDM) measure that requires the State's largest counties, and cities within those counties, to develop and adopt CTR Plans by ordinances. The CTR law was amended by the Commute Trip Reduction Efficiency Act of 2006. This legislation defined the CTR affected area as the shared contiguous Urban Growth Area (UGA) boundaries of the Cities of Yakima, Selah, Moxee and Union Gap. These plans require major (affected) employers (those with over one-hundred employees) to implement programs aimed at reducing the number of single-occupant vehicle (SOV) commute trips made by their employees to the worksite.