Locals' feelings mixed on interchange

'Diamond diverge' has been successful in Missouri city

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When Barry Lyons first heard about the idea to replace the nearly 50-year-old cloverleaf interchange at the intersection of Route 19 and Interstate 70 in Washington County with an innovative new "diverging diamond" design, he admits he thought it was "nuts."

"I thought, not another [traffic] signal on Route 19," Mr. Lyons said.

The design, which is gaining traction nationwide among both engineers and the motoring public -- it was named one of the best engineering innovations of 2009 by Popular Science magazine -- will actually require two more traffic signals on Route 19.

"The more we researched it, the more we found out that it was a workable solution" to alleviate a congested area that serves upwards of 70,000 vehicles per day, Mr. Lyons said.

How could two additional signals in an area already littered with them solve traffic tie-ups and, according to Mr. Lyons, an "extremely high" number of accidents?

It's all in the design and traffic flow, said Mr. Lyons, who is project manager for the state Department of Transportation's latest initiative to save money and ease congestion along one of the busiest corridors in the county.

Mr. Lyons, along with engineers and other officials from PennDOT, unveiled plans for the $65 million diverging diamond interchange at a public open house Wednesday in South Strabane.

Some of the 60 residents and local officials who turned out for the open house said they were impressed. Others, not so much.

"It's going to be better," said Wayne Wicks of Pleasant Hills, who travels through the interchange with his wife, Claudia, at least once a week. "But there's just a plethora of lights."

"And people zigzagging back and forth," Mrs. Wicks said. "They don't know where they're going."

The couple said they instead favored ramps elevated above the roadway, which are being constructed two miles east of the interchange, at the junction of I-70 and I-79 South.

But designing elevated ramps or even a larger cloverleaf, such as the one located at the junction of Route 43 and I-70, isn't economically feasible, Mr. Lyons said, because it would require acquisition of some prime commercial properties, including a Home Depot, Giant Eagle and the Washington Mall.

Instead, PennDOT is moving forward and hopes to bid the project in the summer of 2014, with construction to begin later that year. It should be completed by 2016, said David M. Kozel, project manager for the design firm Gannett Fleming.

The design eliminates the need for left-hand turns across traffic through the use of marked crossover lanes, requiring motorists on Route 19 to drive on the left side of the road before entering ramps.

Those ramps will be elongated and devoted to exit or entrance -- unlike the current design, which forces entering and exiting vehicles to use the same 500 feet of ramp space.

The diverging diamond also will enable motorists to have a larger space to merge onto the interstate at a higher rate of speed, making traffic flow more efficient.

Although the new design may seem confusing at first, well-marked roadways and signs eased concerns from motorists in Springfield, Mo., where use of the diverging diamond was pioneered in 2009.

"Since it's been open, it's been a rousing success," said Jack Wang, Missouri Department of Transportation community relations specialist, about the design, which has been implemented in 11 other locations throughout the U.S.

The diverging diamond has not yet been used in Pennsylvania, but Mr. Wang said public outreach efforts also helped to educate motorists who were unfamiliar with the concept.

"The drivers have gotten educated really quickly on how to navigate it," Mr. Wang said. "It's starting to catch on."

According to the Federal Highway Administration, the design reduced crashes, improved traffic flow and cost less to build than a more traditional reconstruction.

And a survey by Mr. Wang's department indicated that 97 percent of drivers felt safer in the new interchange and that a 60 percent reduction in crashes was reported.

PennDOT district Executive Joe Szczur said the 50-mile path along I-70 between New Stanton and Washington includes 21 interchanges that are "functionally obsolete" because of deficient bridges and narrow roadways. In today's dollars, they will cost about $1.5 billion to upgrade, he said.

"This was all built in the 1960s, so both the interstate and the interchange are substandard," Mr. Lyons said.

Though the I-70 bridge over Route 19 is structurally sound, it will need major work, especially the eastbound side, which will be raised from 14'2" to 16'6" -- the standard size to accommodate a major arterial road like Route 19.

"We don't have to replace it," Mr. Lyons said. "We can rehab it. It's a significant savings."

The 1.5-mile, heavily congested trail from Beau Street to the I-79 North junction also will be expanded in both directions as part of the same project, from two lanes to three.

Perhaps most importantly to commuters such as Paul Dodworth of South Strabane, the junction between I-70 West and I-79 North will be widened to four lanes, two in each direction.

"I think it's a great idea," Mr. Dodworth said. "The fact that you have people trying to get on and off the interstate is a major problem."

After those improvements are completed in 2016, Mr. Szczur said work will begin to widen the road to three lanes in each direction between the Beau Street exit of I-70 to the I-79 South junction.

During construction of both phases, two lanes on I-70 should be open most of the time, with single-lane closures during off-peak hours, Mr. Lyons said.

Once the project is complete, the new traffic lights will sync with those at the Oak Springs Road intersection and the intersection with Trinity Point and Strabane Square.

PennDOT will have more public meetings as the project nears construction.

More details of the design are available at www.divergingdiamond.com .

Janice Crompton: jcrompton@post-gazette.com or 412-851-1867.


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