Motivation Urban road networks are severely congested with economic development, resulting in increased travel times, air pollution, noise, and traffic crashes. As shown by the National Congestion Measures between 1982 and 2011, provided by the 2012 Urban Mobility Report [1], congestion has increased substantially over the 30 years, and is "recovering" from the economic recession during 2009. The delay per commuter in 2011 is 38 hours, which is equivalent to 5 days of vacation per year. Adding more capacity by providing more road lanes and more public transportation is the most fundamental congestion solution in most growing urban regions to satisfy the increasing travel demand. However, road capacity almost always increases in a slower rate than the demand growth. As shown by the Road Growth and Mobility Level Exhibit [1] (Figure 1), 56 in 101 study areas have travel demand growth 30% faster than supply, and only 17 areas have a less than 10% gap between demand and supply growth. Furthermore, accidents or work zones may create bottlenecks on the road and seriously downgrade the road capacity. It is not economically justified and hardly possible to satisfy the increasing peak hour demand. An economical way is leveling the time fluctuation of traffic demand in order to decrease the imbalance between road capacity and traffic demand during the peak-hours.