Sometimes called value pricing - is a way of harnessing the power of the market to reduce the waste associated with traffic congestion. Congestion pricing works by shifting purely discretionary rush hour highway travel to other transportation modes or to off-peak periods, taking advantage of the fact that the majority of rush hour drivers on a typical urban highway are not commuters. By removing a fraction (even as small as 5%) of the vehicles from a congested roadway, pricing enables the system to flow much more efficiently, allowing more cars to move through the same physical space. There are four main types of pricing strategies: 1) Variably priced lanes, involving variable tolls on separated lanes within a highway, such as Express Toll Lanes or HOT Lanes, i.e. High Occupancy Toll lanes; 2) Variable tolls on entire roadways - both on toll roads and bridges, as well as on existing toll-free facilities during rush hours; 3) Cordon charges - either variable or fixed charges to drive within or into a congested area within a city; and 4) Area-wide charges - per-mile charges on all roads within an area that may vary by level of congestion.