I-75 South Metro Express Lanes Critical Addition to Georgia Interstate
Striving to relieve congestion on crowded Interstate 75 south of Atlanta, the Georgia Department of Transportation (GDOT) is adding two reversible express lanes in Henry and Clayton counties, which will be the first reversible express lanes in the state.
“The I-75 South Metro Express Lanes are a critical addition to Georgia’s interstate system,” says Jill Goldberg, Spokesperson for the Department. “GDOT is delivering this innovative design-build project in partnership with the State Road and Tollway Authority (SRTA) to provide motorists options and choices to manage their travels in one of the state’s busiest north-south corridors.”
The $226 million project corridor extends 12 miles, with two at-grade reversible lanes being added at grade in the median between the northbound and southbound lanes. The corridor also includes three general-purpose lanes in each direction, plus a shoulder. Funding sources include Toll Revenue Bonds, state motor fuel tax and 80 percent federal funding. GDOT officials expect the lanes will provide more reliable trip times and bring economic benefits to the area’s residents.
“The Georgia DOT and agency partner, the State Road and Tollway Authority, broke new ground in terms of coordination and development of a civil infrastructure project that will be been tolled,” says Tom Hutchinson, Tolls Project Manager for HNTB Corp. in Atlanta, the program management consultant for GDOT. “The coordination has been successful, and we have been able to work together to deliver one of the most complex infrastructure projects in the state.”
The team drew on experiences of other departments and experts around the country in the planning, designing and constructing of the limited-access reversible toll lanes.
The department selected the design-build team of C.W. Matthews Contracting Co. of Marietta, Georgia, and Arcadis US in Atlanta, and awarded the project in July 2013. Matthews was founded in 1946 to grade farm ponds. It has since evolved into a highway and heavy construction contractor with offices in Georgia, North Carolina and Florida.
“Design-build affords benefit on a project, in terms of schedule and cost,” Hutchinson says. “More complex projects benefit from having the designer working hand-in-hand with the contractor in a contractual relationship.”
Construction began in October 2014, and work is more than 80 percent complete and tolling infrastructure more than 95 percent complete, with construction expected to finish by the end of the year. The new tolls lanes are scheduled to open in early 2017, after testing wraps up.
I-75 South Metro is part of a larger Georgia Express Lanes System in which tolled lanes run alongside interstates in highly congested Atlanta. Additional Georgia Express Lanes include the existing I-85 Express Lanes, and the Northwest Corridor Express Lanes project and the I-85 Extension Express Lanes project, which are scheduled to open in 2018.
Tim Tommey, District Area Engineer with GDOT, considers the phased, design-build delivery approach one of the project’s challenges. The design-build team completed work in toll areas and then turned over each of those seven portions of less than a mile for the tolling equipment to be installed.
“Rather than build the highway first and add the toll technology second, GDOT worked with the contractor to deliver the project in five distinct phases,” Toomey explains. “This allowed for the tolling systems and technology to be installed along with the roadway construction, resulting in a more efficient project timeline. To date, each of the segments has been delivered on time.”
He credits communication and coordination in the field and the use of a document management tool with its success. Additionally, members from the department, the design-build team, federal officials, SRTA and the Atlanta Regional Commission meet monthly to coordinate the integration of construction, toll systems and access control system operation, and public education.
Construction of the reversible lanes and a shoulder is similar to any other road-building project, with grading, placing an aggregate base layer and paving with asphalt. Crews must work around flowing traffic, with single-lane closures allowed only from 9 p.m. until 5 a.m. northbound and 7 a.m. southbound during the week and double-lane closures from 12 a.m. until 5 a.m. northbound and 7 a.m. southbound, Monday through Sunday.
Work also includes a new flyover ramp at I-675 to access the express lanes, slip lanes and several other bridges.
The design-build team has taken steps to ensure safety on the reversible lanes with an access control system, with signage and warning and resistance gates to prevent drivers from entering against traffic flow. “Vehicles will not be able to enter the system heading in the wrong direction,” Hutchinson says.
Additionally, C.W. Matthews built concrete barriers between the general and reversible express lanes. As part of the routine maintenance and operations of the reversible facility, the department will drive the length of the lanes to check for any vehicles and debris before reopening the lanes.
The reversible lanes will have access points for emergency vehicles. Local firefighters and police received training about how to respond to emergencies in the toll lanes and how to use the keypad codes to gain entry.
GDOT and SRTA developed and are implementing variable tolling technology on I-75 South Metro Express. Vehicles will use a Peach Pass, which will automatically deduct the correct fee. Prices will rise and fall based on the traffic at that time, with peak travel times higher than other times of the day. Busses, state-registered vanpools and emergency vehicles will ride free.
New park and ride lots are in the planning stages along the corridor to maximize the benefits for those using transit vehicles. Riders receive the advantages of the express lanes at no additional costs, and can also use new on-board wi-fi services.
“Since the I-75 South Metro Express Lane is a reversible system, the toll zone equipment also accommodates reversible operations,” Hutchinson says. “This equipment can serve a dual purpose depending on the direction of the flow of traffic.”
The tolling system required a new approach to some aspects of the construction. For example, the contractor used fiber reinforced concrete as an alternative to metal rebar in proximity to the toll zone locations to avoid conflicts with the systems.
“There are vehicle detection loops cut into the concrete in the toll zones,” Hutchinson explained. “The rebar would interfere with those loops.”
The department expects approximately 7.9 million annual trips on the I-75 South Metro Express Lanes, which is expected to save approximately 12 minutes on each trip, after the project opens.