Posted: 10:09 p.m. Thursday, May 31, 2012
What is a Diverging Diamond Interchange?
Diverging diamond interchanges are often used at intersections located beneath or above freeway bridges. At a diverging diamond interchange, traffic briefly crosses over to the left (opposite) side of the roadway, safely guided by traffic signals at each crossover. This allows vehicles to turn left onto freeway on-ramps without stopping and without conflicting with through traffic.
In other words, traffic is briefly routed to the opposite side of the road at an intersection. Because vehicles are now traveling on the left side of the road, they are one the same side of the road as freeway on-ramps and are able to take the freeway on-ramp or other exit without waiting in separate turn lanes as in traditional intersections. Through traffic simply travels through the intersection and switches back to the right side of the road after the intersection, all guided by roadway signs and markings.
Diverging diamond interchanges feature signs, striping, curbs, headlight glare screens and concrete barriers to guide and safely separate opposing traffic as it moves through the interchange.
Diverging diamond interchanges can move increased traffic more quickly and safely than traditional intersections- and can often be constructed at a lower cost.
∙ Free, unsignalized left turns (onto freeway on-ramps, etc.) help reduce congestion
∙ Fewer signal phases and shorter wait at traffic lights by eliminating signalized left-hand turn lights. For example, the Moana Lane diverging diamond interchange in Reno will feature two signal phases as opposed to the previous three
∙ Diverging diamond interchanges often reduce by half the number of conflict points at which vehicles can potentially collide (by reducing potential crash points between vehicles turning left onto the highway and opposing arterial roadway traffic)
∙ Diverging diamond interchanges can be more cost and time-effective to build, as they often require less land and fewer potentially-costly changes to existing road structures
∙ Heightened pedestrian/bicyclist safety can be provided by designated, enclosed shared use paths built in the middle of the diamond interchange
∙ Makes wrong way entry onto freeway ramps extremely difficult
∙ Snow can continue to be removed/plowed in diverging diamond interchanges