Transform 285/400 Aims to Improve Atlanta’s Traffic Flow
An Investment for the Future: Better Access and Improved Safety for Steadily Growing Atlanta is the Main Goal of Transform 285/400
The Georgia Department of Transportation’s (GDOT) $800 million Transform 285/400 project aims to reduce congestion and enhance safety around the Interstate 285/State Route 400 interchange in Atlanta.
“The 285/400 interchange is located in a very heavily traveled corridor,” says Marlo Clowers, Project Manager for GDOT and an Atlanta native, with 23 years with the department. “The perimeter area is one of the fastest growing in Metro Atlanta.”
More than 400,000 vehicles per day pass through the interchange. About 2 million people travel along I-285 daily. The area has significant retail, commercial, and residential developments and three hospitals.
“This project is to help reduce congestion through the area, improve the flow of traffic and improve safety,” Clowers explains.
Scope of the Project
The Transform 285/400 project, the largest project currently under construction by GDOT, creates new flyover ramps for the interchange. The department is replacing some existing ramp movements that lack the capacity to handle the traffic volume and building new direct flyover ramps. In addition, the project includes collector-distributor (CD) lanes, which will connect to the flyover ramps, and other upgrades to 4.3 miles of I-285 west of Roswell Road to east of Ashford Dunwoody Road and 6.2 miles along SR 400 from the Glenridge Connector to Spalding Drive. GDOT purchased some additional right of way and easements along I-285 and SR 400.
“Part of the benefit of the CD lanes is controlling where all of the entering and exiting will happen,” Clowers says. “The turbulence and weaving to enter and exit will happen in designated lanes within a barrier-separated network. The CD lanes will allow the mainline traffic to continue through, separate from the entering and exiting traffic, which reduces the potential for crashes that could affect traffic flow.”
GDOT combined two single projects, one for the interchange reconstruction and the second for the CD lanes, into one design-build-finance, public-private partnership (P3) project. State, federal, and local funds will be used in addition to the P3 financing. GDOT will pay the private partner back over time.
“P3 is a tool GDOT is using on some of large scale mobility improvement projects, to allow us to maintain the infrastructure in a state of good repair with the funding constraints the agency has,” Clowers says. “We may also be able to benefit from some innovation from private industry.”
North Perimeter Contractors (NPC) of Atlanta, a subsidiary of Ferrovial Agroman US Corp., of Austin, Texas, received the $457 million contract in 2015 and began construction in February 2017.
Louis Berger Group of Morristown, New Jersey, serves as the engineer of record for I-285, and Neel-Shaffer with offices in Atlanta handled engineering for the SR 400 portion of the project. In a design-build project, design takes place concurrently with construction and prerequisite activities, such as geotechnical investigations and utility relocations.
The GDOT Transform 285/400 project management team includes HNTB, Atlanta, which also serves as the program management consultant for of GDOT’s Office of Innovative Deliver; Jacobs, with offices in Atlanta; and Michael Baker International with offices in Norcross, Georgia.
Major Mobility Investment
“This project is opening the door for the large-scale mobility improvement projects within the Major Mobility Investment Program,” Clowers says.
The Major Mobility Investment Program (MMIP) includes state and federally funded large-scale transportation projects dedicated to improving roads and bridges. Together, these projects will create additional capacity, improve the movement of freight, provide operational improvements and efficiencies, enhance safety and decrease travel times across Georgia. The MMIP represents significant long-term investment in the state’s transportation infrastructure. Many of the projects support regional transit providers and enhance existing and future transit operations, explains Tim Matthews, Program Manager for MMIP in a statement. Transform 285/400 in not part of the MMIP program.
“We are providing a free option for mobility,” Clowers adds. “Transform 285/400 has no toll or express lanes. It is benefiting all of the users of I-285 and SR 400 in this highly developed area.”
NPC will build 32 bridges, 20 within the core interchange. Some bridges have curved steel girders. The longest bridge is more than 1.5 miles long and 90 feet tall.
“Alignments through the core interchange are challenging, and the bridge structures are complex,” Clowers says. “We have some massive, complicated structures being constructed.”
Three bridges, at Mount Vernon Highway, Peachtree Dunwoody Road and Glenridge Drive, have concrete girders. Additionally, a diverging diamond interchange will require the existing bridge over Abernathy Road to be reconstructed, says Annalysce Baker, Spokesperson for NPC.
“The existing bridge and new bridges will have less columns to accommodate the new expanded roadway,” Baker says.
When complete, the project will have more than 150 walls of different types, including mechanically stabilized earth retaining walls and cut walls. In addition, 16 sound barriers are being constructed.
Traffic continues to flow on the highways and interchange during construction. Some of the steel erection has taken place at night or with traffic pacing.
“The challenge is you have to build massive flyover bridges while traffic is moving around and under them,” Clowers says. “We periodically change how and where ramps tie in, as construction progresses, which presents driver expectancy and safety challenges. We have to make sure we are not so focused on getting the project built that we present problems for drivers.”
NPC has built some temporary ramps, with new pavement adjacent to an old ramp, to create space to build the new ramps and bridges. Crews also are protecting streams and manmade lakes during construction.
A unique aspect of the project is that it has an eruv, a symbolic boundary for people of the Jewish faith. Some of the features of SR 400 serve that purpose for Congregation B’nai Torah during the Sabbath. GDOT consults with the rabbi if construction is going to take place near the boundary to ensure the boundary remains intact on the Sabbath.
“There are complex rules regarding eruv construction and inspection,” Baker says. “If any section of an eruv is broken or out of alignment the entire eruv structure is considered invalid. Due to the eruv’s importance, Jewish communities with an eruv have inspectors who monitor the enclosures integrity to ensure it is intact.”
Throughout the project, NPC also has taken steps to control erosion.
“We install exclusionary flaps in culverts to minimize any impacts of construction to federally protected birds,” Baker says. “We inspect all flaps before the nesting season and add new flaps if needed.”
NPC has employed drones to conduct topography surveys, creating an image and 3-D model of the surveyed area. GDOT also is taking advantage of drone technology to take photos and videos to monitor progress along the corridors.
The contractual open to traffic date is in October 2020. However, GDOT will open up sections of the project as they are finished.
GDOT and NPC have worked well as a team, Clowers says. GDOT and the NPC co-located, which helps foster communication. “NPC is proud to increase mobility and improve safety for the commuters in metro-Atlanta and the State of Georgia,” Baker says.
Clowers looks forward to the project’s completion and how it will transform this portion of the metropolitan area’s transportation infrastructure.
“It’s an honor to be able to make a significant impact in the state where I live in one of the premier areas of Atlanta,” Clowers concludes. “I am also excited about opening the way to larger mobility improvements.”