Continuous flow intersection: A public private partnership

When traffic problems are caused by heavy left-turn movements, traditional tactics include the use of special signal phases and channelization, enforcement personnel, widening the right-of-way, improving alternate routing or grade separation. Continuous Flow Intersection (CFI) provides an at-grade spatial solution that improves traffic operation beyond the capacity of a conventional intersection. The primary design element of the CFI, as it is configured at the National Aviation and Transportation Center (NAT Center), Long Island, New York (first installation in the world) is to remove the conflict between left-turning vehicles and the oncoming traffic. The CFI design accomplishes this by introducing a left-turn bay placed to the left of oncoming traffic. This bay is accessed by the creation of a midblock, signalized intersection. Traffic is permitted to load the left-turn bay and cross-street traffic, thus eliminating any traffic conflicts. The signal phase servicing through traffic also services protected left-turn movements; so oncoming traffic does not conflict with left-turn vehicles. As a result of this design, multiphase signal operations to provide protected left-turn movements are eliminated, enhancing intersection signal efficiency. When combined with vehicle sensor technology, new levels of signalization optimization can be achieved. The New York Times reported that this design is one of the most innovative traffic designs in the past thirty years. Not only is travel flow enhanced along with capacity, there is also a demonstrated reduction in existing vehicle related pollution. Although presently configured as a quarter interchange this same CFI can be expanded to a full scale interchange with concomitant benefits.