Northwest Corridor Express Lanes Reduce Atlanta Commute Times

When plans to improve Interstate 75 (I-75) northwest of Atlanta were first introduced in the early 2000s, the region had already gained a reputation among motorists as being one of the slowest and most congested for travelers.

Today that commute time has been drastically reduced, thanks to a comprehensive program that culminated with the recent completion of the Northwest Corridor Express Lanes.

“The new roadway has reduced one-way commute times by as much as 45 minutes every day,” said Robert Moses, WSP project manager. “Many express lane users have proclaimed the benefits to them as ‘life changing.’”

The Northwest Corridor Express Lanes are part of a 30-mile network of optional traffic lanes created by the Georgia Department of Transportation (GDOT) to improve mobility and reduce trip times throughout the metropolitan Atlanta region. The project included three intersecting interstate highways — Interstates 75, 575 and 285 — and 39 bridges.

With a cost of $834 million, it is the largest transportation project in Georgia history. It is also the first Georgia transportation project to be procured as a design-build public-private partnership (P3) project.

The toll lanes are reversible to accommodate traffic flow patterns, operating southbound in the morning, and northbound in the evening. The lanes use dynamic pricing, with rates rising as demand increases during peak travel times and falling at off-peak times, giving drivers the choice to pay to bypass congestion. Motorists with a registered Peach Pass can use the express lanes, which cost about 10 cents a mile during peak hours, and 50 cents for the entire trip during other times, regardless of length of travel.

Since it opened to traffic in September 2018, the Northwest Corridor has had a tremendous impact on the community and region. In its first month of operation, the express lanes recorded more than 400,000 trips.

The Northwest Corridor is one of Atlanta’s most economically vital regions, containing several major activity and employment centers. Rapid growth of the region’s residential population along with employment expansion is expected to continue through 2035. Without transportation improvements to accommodate this growth, congestion was expected to worsen, creating further loss of mobility.

WSP USA has been involved with the Northwest Corridor project since the beginning, serving in multiple roles on behalf of GDOT. During the first phase of the project, which ran from 2001-2008, WSP served as the prime consultant, developing engineering concepts to address congestion on I-75 and I-575. As the environmental lead, WSP evaluated the viability of those concepts through development of the alternatives analysis/draft environmental impact statement (AA/DEIS).

The AA/DEIS included highway solutions, such as adding high-occupancy vehicle (HOV) and truck-only lanes, developed in collaboration with GDOT; as well as transit solutions, such as bus rapid transit (BRT) with stations along the corridors, developed in conjunction with Georgia Regional Transportation Authority (GRTA).

“This project required numerous innovations, accommodations and considerations, including solutions that addressed impacts to the traveling public, environmentally sensitive areas, and the estimated duration and cost of construction,” said Moses, who has served as WSP’s project manager since the retirement of original project manager, Roger Palmer.

GDOT’s project began as an extension of the existing HOV system, but expanded when the GRTA study determined that BRT operating in the proposed HOV system along I-75 would be a more effective solution. Eventually, the preferred solution was determined to include the creation of reversible managed express lanes along the corridor.

WSP’s work played a key role in reaching the final decision, which included an extensive traffic study and analysis for the corridors, and the definition of impacts to environmental resources, right of way, existing development and structures.

During the second phase of the project, from 2009 through completion of the project, WSP prepared the supplemental DEIS, the final EIS and the record of decision (ROD) approved by the Federal Highway Administration in 2013, which paved the way for construction to begin.

“During construction, WSP prepared 10 environmental reevaluations to address changes that were requested by the P3 team,” Moses added.

In addition to WSP, the GDOT project team included HNTB Corporation, program manager and Michael Baker International, design reviewer. The P3 team was Northwest Express Roadbuilders (NWER), a joint venture of Archer Western and Hubbard Construction, builder; with Parsons as lead designer and Atkins, owner’s verification firm.

Through innovative designs, construction techniques, and alternative technical concepts, the project team saved GDOT an estimated $150 million from the original anticipated cost of the project.

“The team responded to the inherent challenges of such a large and complex project with alternative technical concepts, accelerated bridge construction techniques, and creative solutions, resulting a significant cost savings,” Moses said.

Within months of opening, the Northwest Corridor project was earning accolades for its achievements, receiving several statewide, national and international industry awards.

Most recently, the project was recognized by the International Road Federation (IRF) with its 2019 Global Roads Achievement Award in the Program Management category.

Presented in November, the Northwest Corridor was one of a dozen projects from around the world recognized by IRF for innovation across major road and highway disciplines. An international panel of senior road development specialists selected the winners.

“This project represents many years of effort and dedication from many of our team members,” said Claudia Bilotto, WSP’s environmental lead for the project and now area manager for the WSP Atlanta office. “The Global Roads Achievement Award is affirmation of a very successful project that was a critical project for everyone involved from our Atlanta office for a long time.”

Bilotto represented WSP at the IRF awards ceremony, held in Las Vegas, Nevada on Nov. 20.

In October the project won an America’s Transportation Awards from the American Association of State Highway and Transportation Officials, honored with the People’s Choice Award.

The Design-Build Institute of America awarded the Northwest Corridor project with its National Award of Merit for Transportation in August.

In 2018, the Georgia Partnership for Transportation Quality honored the project with its Preconstruction Grand Award as one of GDOTs most significant transportation achievements.

Roads & Bridges magazine also selected the Northwest Corridor Express Lanes project as the No. 1 project for its Top 10 Roads of 2018 list.

The final design reduced right-of-way acquisition by more than 60 parcels, which further reduced costs and accelerated the delivery of the Northwest Corridor, enabling the project team to meet its aggressive schedule goals.

A phased design and construction approach was used to complete the final design, which required 866 early work package design drawings within a year. The coordinated efforts of nearly 200 full-time engineers during the peak design phase led to the successful completion of 50 early work packages, 157 final packages, and 20 notices of intent.

The P3 team’s construction phasing necessitated the initial large environmental reevaluations prepared by WSP that addressed multiple disciplines across the entire project corridor.

“Subsequent reevaluations tended to focus on specific locations, or specific disciplines, such as sound barriers,” Moses said. “FHWA approvals of the reevaluations were required before the P3 team could implement their changes. The slogan, ‘every day counts’ became ‘every minute counts.’”

As the most comprehensive installment of Georgia’s express lanes system to date, the Northwest Corridor project has raised the bar for design-build project delivery in the state and across the U.S.

Much of what was learned through the Northwest Corridor project has been applied by GDOT to its current Major Mobility Investment Program (MMIP). “The success of the Northwest Corridor project gives GDOT a real-world express lane success that they can point to as they continue to expand the system,” Moses said.

WSP is currently serving GDOT as the general engineering consultant for the I-285/I-20 West Interchange megaproject.

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