Karl Baker

The News Journal

A first-of-a-kind for Delaware road layout will open Saturday on the Del. 72 bridge over Del. 1, and the new design – which directs drivers to veer onto the left side of the road – could cause confusion for those making their way onto the state's primary north-south artery.

Transportation planners say the diamond-shaped configuration is an efficient design that will ease heavy traffic backups that occur daily on Del. 72 during rush hour. Similar to Delaware's adoption of the roundabout years ago, the design – called a diverging diamond interchange – has been in use in Europe for decades.

Unlike the roundabout, however, this road configuration will not require drivers to master new maneuvers, say transportation officials. Consequently, there should be no increase in collisions, they say.

"Roundabout do have a learning curve, but this is a little different," said Geoff Sundstrom, spokesman for the Delaware Department of Transportation. "Once you get into this intersection, it’s really not like you can start turning willy-nilly wherever you want to go. It’s more channelized."

When the rebuilt interchange opens Saturday, eastbound drivers entering Del. 1 from Del. 72 will no longer have to wait for a green left-turn signal before proceeding through oncoming lanes. Instead, they can enter the northbound highway on-ramp directly from the left side of Del. 72. The entrance to the southbound Del. 1 lanes will be located on the right side of the highway and be available to drivers before traffic veers onto the left side.

It is a crisscross pattern that will be metered by traffic signals, one at each end of the interchange. Pedestrians on Del. 72 will walk down a center sidewalk between the two directions of traffic.

"Vehicles that want to go north toward Wilmington, which is a pretty predominant movement at this interchange ... they’ll make a free left-turn,” said Darren O'Neill, highway engineer at the Delaware Department of Transportation.

The $7 million project, which began in June, is meant to carry an increasing load of vehicles after decades of sub-division building booms caused the population to surge around Bear. Chronic, mile-long backups of vehicles waiting to turn left onto Del. 1 have plagued the Bear-area road, said O'Neill.

"That left-turn movement is now going to get flushed out without having to wait at the signal, and that’s a monumental benefit for the people along this road,” said O'Neill.

After construction crews installed overhead signs for the interchange, neighbors contacted O'Neill insisting the workers had hung them facing the wrong direction, not knowing they are meant for drivers on the left side of the road.

"It is (wrong) today," he said Friday. "Tomorrow, it will be on the right side of the road."

If DelDOT had not opted for the diverging diamond design, it would have likely installed large, looping ramps – a far costlier option, O'Neill said.

"We were able to do this construction very, very easily with the existing right-of-way so we saved 75 percent of the time and 75 percent of the cost,” said DelDOT Secretary Jennifer Cohan.

Linda Horan lives in the Fieldstone Crossing subdivision, which lies adjacent to Del. 72 and near Del. 1. Bear roads have progressively become more clogged during her 25 years in the area, she said.

“Traffic is always horrendous the more they’ve built,” Horan said. “We’ve been here for years and years and years ... and it has just been horrible with all the (new) developments.”

Horan, originally from the United Kingdom, is familiar with driving on the left side of the road. Time will tell, she said, whether Delawareans become comfortable with the new interchange, and its segment of left-side driving.

“If it’s going to work, it’s going to work," she said. "We don’t know if it’s going to work until it’s done.”

Although the new interchange configuration will open to drivers Saturday, construction crews will still be on the scene for another month, said O'Neill. There is a rush to finish before the ground freezes, he said.

"We have about 3 to 4 weeks of work (left). We are now in early November so we are trying to maximize every day," he said.

Looking forward, DelDOT is already considering the diverging diamond interchange for other highways, including Del. 273 at I-95.

"If this goes well, then this now becomes another tool in our toolbox," said Cohan.

While the design has existed in Europe for more than a generation, it has emerged recently in the United States. New Jersey is one of five states to not have designed such an interchange, according to Advanced Transportation Solutions, a highway design company. Pennsylvania's first one opened in September in the town of Washington, which lies about 30 miles southwest of Pittsburgh. Hanover, Maryland, is also the home of a diverging diamond interchange.

The design was controversial in Iowa when transportation crews last year built one such interchange over Interstate 80, near Waukee, Iowa. In April, a drunk driver turned the wrong way down an I-80 on-ramp from a diverging diamond and struck a Des Moines police car, killing two officers, a prisoner and himself.

Investigators said the interchange is marked appropriately with signs and markings, and concluded that driver's high level of impairment prompted him to enter the interstate the wrong way.

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O'Neill said the interchange will be safer for drivers in Delaware because they will not make left turns across oncoming lanes, often the cause of deadly angle crashes. Nevertheless, a Delaware State Police officer will help direct traffic on Del. 72 until Wednesday.

"With innovation there’s always a level of risk," said Cohan. "Again we’re saving 75 percent of the time, and 75 percent of the dollars and still getting the traffic (congestion) reduction that we want.”

Kenny Reed, a Bear resident who commutes over Del. 72 is wary of the safety assurances. He agrees road capacity should be increased because "traffic’s always jammed." But Delaware's adoption of roundabouts has not been a complete success, he argues, and the diverging diamond interchange, by directing drivers to the left side of the road, could be similarly confusing.

The first time he saw a roundabout was in a film called European Vacation, he said, which featured a character, played by Chevy Chase, rounding the circular intersection continuously, with no idea how to exit. Delawareans are not always clear on the rules of a roundabout either, he said.

“I don’t think people have got the hang of it yet,” Reed said.

Contact Karl Baker at kbaker@delawareonline.com or (302) 324-2329. Follow him on Twitter @kbaker6.