Today, transportation congestion represents a seriousthreat to the U.S. national economy and affects virtuallyevery aspect of our lives—where we live, where we work,where we shop, and how much we pay for goods andservices. According to the Texas Transportation Institute,road congestion annually results in 3.7 billion hours oftravel delay and 2.3 billion gallons of wasted fuel. Whetherit’s trucks stalled in traffic, cargo stuck at overwhelmed seaports,or airplanes circling over crowded airports, congestion