Intersection designs for today's traffic : increased street congestion calls for greater attention to intersection design.

Rigid adoption of intersection design methods fails to take into account unique needs of intersections that don't meet standard conditions. Intersection design problems lie at the root of much of the rise in congestion. Los Angeles has the worst percentage of bottlenecks, according to Unclogging America's Arteries, a study of performance from 1999-2004. It has five of the top 24 worst areas. One new design is the quadrant roadway intersection (QRI), which removes left turns from the main intersection and adds a roadway in one intersection quadrant, which then accommodates left turns. Conventional designs can work well in certain situations. All of them can use traffic islands to separate conflicting vehicles, street realignments or closures, medians and channelized areas for pedestrian protection. Roundabout intersections eliminate signals and cut delays. The article provides specifications for certain designs, photos and a 10-step process for involving citizens.