On average, HOV lanes carry twice as many persons as regular-use lanes. That translates to accommodating 33 percent of freeway users in just 20 percent of the space, while an adjacent single mixed-flow lane carries 17 percent of the entire freeway's users in the same 20 percent of space.
After years of planning, work on the final segment of the HOV lane started in summer 2009. Caltrans and Metro awarded a design-build contract for the carpool lane--the first such contract let for a freeway project in this part of California. The main advantage to the design-build method is speed of construction, along with greater flexibility to respond to conditions as they arise.