Interstate-85 proposal coming in March

By Cindy Landrum  

JANUARY 26, 2012 12:05 p.m. (0)

A plan to ease congestion along a 22-mile stretch of Interstate 85 in Spartanburg and Greenville counties should be finished by April.

Columbia-based Civil Engineering Consulting Services has been studying options to alleviate congestion from White Horse Road in Greenville County to State 129 in Spartanburg County.

The stretch of interstate is a key transportation artery for tractor trailers supplying some of the Upstate’s largest industrial plants and distribution centers, for Upstate residents working at them and other nearby businesses and for traffic passing through on the way to Atlanta or Charlotte.

A draft report should be finished by early March.

The final report is expected by April 1, giving the state Department of Transportation a list of options to choose from the $9 million it has budgeted for I-85 improvements, said Michael Dennis, project manager with the state DOT.

The options being studied are divided into four areas: travel demand management, modal, operational and capacity, Dennis said.

“We want to extend the life of the corridor,” he said. “We’re looking at doing smaller, easier cheaper projects to push out widening of I-85 as far as we can.”

The report will contain a flow chart indicating how many years each of the options would push back widening the important stretch of road.

One of the options being studied is installing at the State 290 interchange a diverging diamond, a popular option in France, but one that has only been used in three states.

Diverging diamonds temporarily put drivers on the left side of the road at interchanges to eliminate the need for drivers to make left turns in front of oncoming traffic.

The first diverging diamond was built in Springfield, Mo., in 2009. Missouri has three diverging diamonds, while Utah and Tennessee have one each.

In a diverging diamond, traffic lights allow lanes to crisscross at an intersection – allowing drivers to make left turns without having to negotiate oncoming traffic – before putting them back in their regular lanes of traffic.

Drivers making right turns are still allowed to do so.

The configuration has been shown to reduce traffic accidents at those interchanges by 50 percent.

According to a Federal Highway Administration report, the interchanges can handle twice as many left turns per hour as conventional interchanges, reducing delays for drivers.

Among other options expected to be included in the final report are “park and ride” areas, an express bus along U.S. 29, more overhead message boards, bus rapid transit to the airport, extending ramps, widening some portions of I-85 and having collector-distribution systems similar to the one for northbound traffic around State 291, Mauldin Road and Augusta Road that keeps traffic from having to get on the interstate only to get off in an exit or two.