Fort Mill I-77 interchange redesign first of its kind in SC

York County is on track to build South Carolina’s first “double crossover diamond interchange” – an alternative transportation design that the Federal Highway Administration says helps reduce traffic collisions and delays.

The new design is planned for the Interstate 77 and Gold Hill Road interchange near Fort Mill. The nearly $12 million road project is under review by the state Department of Transportation.

Transportation officials can use the “double crossover” feature to address congestion and safety problems at busy intersections. Gold Hill Road is the second busiest thoroughfare in the Fort Mill area, with more than 33,000 drivers daily.

County leaders and SCDOT introduced the new intersection design plan for Gold Hill Road several years ago. A public hearing was held where the community discussed three redesign options. Officials preferred the double crossover diamond interchange because the project would require less expensive right-of-way land purchases than other options, and the design maximizes car capacity at the interchange while reducing congestion.

The new interchange design can be found in many states, but it might be unfamiliar to local drivers.

Here’s how it works:

▪ When approaching the interchange from east or west, drivers will encounter a traffic signal intersection.

▪ Eastbound drivers on Gold Hill Road will be able to enter I-77 South in a free-flow right turn lane.

▪ Eastbound drivers on Gold Hill Road wanting to enter I-77 North will go through one traffic signal then temporarily cross to the left side of the road before traveling over the bridge and entering the interstate via a left-hand free-flow lane.

▪ Westbound drivers on Gold Hill Road will be able to enter I-77 North in a free-flow right turn lane.

▪ Westbound drivers on Gold Hill Road wanting to enter I-77 South will go through one traffic signal then temporarily cross to the left side of the road before traveling over the bridge and entering the interstate via a left-hand free-flow lane.

Unique features of the interchange include:

▪ Cars temporarily diverge to the opposite side of the road, under control of a traffic signal.

▪ Traffic entering or exiting the interstate does not have to cross oncoming traffic to make a left turn.

▪ Drivers will be guided by directional signs, painted markings on the roadway, and the interchange will have a concrete barrier and raised medians to avoid wrong-way travel.

▪ Pedestrians and cyclists have marked crossings and paths.

The double crossover diamond interchange at Gold Hill Road was approved by York County voters in 2011 as part of the county’s 1-cent sales tax program to pay for transportation projects. The Pennies for Progress program is in the preliminary stages of the project. Construction could begin in early 2017.

County officials say the redesign should help better manage the high-traffic Fort Mill interchange.

This story was originally published August 16, 2015 at 9:15 PM with the headline "Fort Mill I-77 interchange redesign first of its kind in SC."