The parallel flow intersection: A new high capacity urban intersection

This paper by the inventor presents the patented parallel flow intersection (paraflow or PFI) as a low cost alternative for reducing congestion on urban arterial streets. The public cost of traffic congestion is enormous in terms of delay and wasted fuel consumption. According to the Texas Transportation Institute, the cost of congestion in the United States for 2007 was $87 billion (US) in lost time and 2.8 billion gallons (10.6 billion liters) of wasted fuel. A single congested intersection can cost several million dollars annually and grade-separations are a high impact and high cost solution. One alternative to interchange construction, however, is the paraflow, an at-grade intersection that achieves high efficiency by reducing the number of signal phases per cycle to two or three. As a result, lost time is minimized at the intersection due to the compounding benefits of fewer all-red phases, shorter cycle length and less queue start-up and dispersion time to reach a level of capacity that can rival an interchange. And unlike other unconventional high capacity intersection designs, the paraflow provides intuitive direct left turns that are made nearly at the same location as a conventional intersection. Channelization and other traffic control measures provide positive guidance to give drivers confidence in making proper turn maneuvers. The paraflow can be expected to be safer for motorists than a conventional intersection since the paraflow has fewer crossing conflicts and no permitted left turns. Safety is also improved for pedestrians and bicyclists by again eliminating permitted left turns, providing traffic islands that serve as refuges, and shorter crossings at crosswalks. The paraflow is adaptable to the physical site and can maintain or improve access to corner properties. The paraflow can be constructed in various forms both at-grade and grade-separated. In combination with other high capacity intersect