Crossing into new territory
‘Diverging Diamond Interchanges’ reduce traffic, accidents, engineers say
A new traffic pattern requiring you to drive on the “wrong side” of the road for safety will soon debut in South Florida.
The state is planning to introduce Diverging Diamond Interchanges on some South Florida expressways.
For the region’s traffic-weary drivers, it could mean an end to getting trapped under overpasses, backed up through intersections, blocking cross streets and waiting through three red-light cycles while trying to make a left turn through oncoming traffic onto an expressway.
As you approach a Diverging Diamond Interchange you will
stop at traffic lights, then follow the marked crossover lanes to the left so it feels like you’re driving on the wrong side of the road. From there you will be able to make a smooth left turn onto an expressway or continue going straight until the lanes lead you back to the right side of the road. It works the same for traffic flowing in the opposite direction.
These interchanges can also accommodate sidewalks and bicycle lanes.
Traffic engineers call the design safer, faster and more convenient.
The Federal Highway Administration agreed but also cited disadvantages that included the potential for driver confusion and turning the wrong way at the crossover points.
The first two Diverging Diamond Interchanges in South Florida are being built on Northwest 27th and 57th avenues where they intersect with the Dolphin Expressway. They will open in the spring, according to Miami-Dade Expressway Authority deputy executive director Juan Toledo.
“You create a free-flow movement in and out of the expressways,” he said. “You also remove conflict points that exist in a standard interchange where you typically have an accident, so you’re improving safety and operations.”
Traditional intersections have 26 conflict points — a technical term for areas of an intersection where collisions can occur — but Diverging Diamond Interchanges have only 14 of these potential crash areas, reducing the risk of accidents by about half.
At least five Diverging Diamond Interchanges are being designed for the Sawgrass Expressway at Coral Ridge Drive, Sample Road, and Commercial, Oakland Park and Sunrise boulevards across Broward County.
There is also talk of a Diverging Diamond Interchange on Interstate 95 at Cypress Creek Road in Fort Lauderdale, two more on I-95 at Northlake Boulevard and 45th Street in West Palm Beach, and one on the Homestead Extension of Florida’s Turnpike at Northwest 170th Street in Miami-Dade.
Sarasota opened Florida’s first and only other Diverging Diamond Interchange in May and Leigh Holt said it has worked “amazingly well.”
“We have a citizens advisory committee that met Monday night and they’re usually quite cantankerous, but they love the diverging diamond,” said the planning manager for the Sarasota/ Manatee Metropolitan Planning Organization.
Located under Interstate 75 on University Parkway, the $74.5 million, 12-lane project is one of 39 crossover interchanges the state is working on.
Holt said it was still too soon to know whether collisions have been reduced, but traffic congestion is way down.
“We hosted the world rowing championships with 40,000 additional people going through that intersection throughout the week ... from all over the world,” she said. “It moved traffic through a place where, for many years, we had traffic backups.”
Toledo said a public awareness campaign will begin in January to introduce South Florida drivers to the new traffic pattern approaching the Dolphin Expressway.
“It’s something the driving public isn’t really used to,” he said.
The first Diverging Diamond Interchange in the U.S. opened in Springfield, Mo., in 2009. Since then, 88 have sprung up across the country in places including suburban Atlanta, Kansas City, Mo., and Columbus, Ohio.