The SR 400 Express Lanes Project is an $11 billion, 50-year public-private partnership (P3) delivering 16 miles of new tolled express lanes along Georgia State Route 400 in metro Atlanta, running from the North Springs MARTA Station in Sandy Springs north to McFarland Parkway in Forsyth County, with an integrated Bus Rapid Transit (BRT) component connecting to the MARTA rail network. Developed by the SR 400 Peach Partners consortium — comprising ACS Infra (IRIDIUM), Acciona, and Meridiam — the project is the largest P3 bond financing and the largest TIFIA loan in US history, and Georgia’s first revenue-risk managed lanes project where the private partner assumes full toll revenue risk for the concession period. Construction officially began on March 9, 2026, with GDOT declaring it the largest transportation infrastructure project in Georgia state history, with heavy construction scheduled for Q3 2026 and the new toll lanes expected to open in 2031.

Project Overview

Type: Design-Build-Finance-Operate-Maintain (DBFOM) tolled express lanes P3

Location: SR 400 corridor, metro Atlanta — North Springs MARTA Station (Sandy Springs, Fulton County) to McFarland Parkway (Forsyth County)

Scope: 16 miles of new tolled express lanes; 2 lanes each direction (North Springs to McGinnis Ferry Road); 1 lane each direction (McGinnis Ferry to McFarland Parkway)

Total investment: $10.99 billion

Design-build construction cost: $4.6 billion (estimated)

Upfront concession payment to GDOT/SRTA: $3.8–$4.05 billion

TIFIA loan: $3.89 billion (largest in programme history)

Private Activity Bonds (PABs): $3.44 billion (largest highway bond financing in US history; 1.7x oversubscribed, 90+ investors)

Concession duration: 50 years (DBFOM); 56-year total P3 term

Early works (site prep, tree clearing, utility relocation, geotechnical investigations): began fall 2025; heavy construction to begin spring/summer 2026 starting near Spalding Drive, Holcomb Bridge Road, and Union Hill Road

Full construction officially commenced: March 9, 2026

Target completion: Spring 2031

Award: PFI Americas Infrastructure Deal of the Year 2025

Transit integration: $75 million BRT-related improvements; $26 million directly to MARTA; two new BRT stations at Holcomb Bridge Road and North Point Mall; BRT to share express lanes for ~12 miles

Tolling: Dynamic variable pricing via Peach Pass; travel expected to be up to 30% faster than general-purpose lanes at peak

Bridge works: Replacement/widening of Pitts Road, Roberts Drive, and Kimball Bridge spans

No existing lanes removed; taxpayer funding: zero construction/operating costs to public

Growth projection: 144,000 new residents and 114,000 new jobs in corridor by 2050

Project Team

Concessionaire: SR 400 Peach Partners LLC

Equity partners (33.33% each): ACS Infra (IRIDIUM); Acciona; Meridiam

ACS Infra Chairwoman & CEO / IRIDIUM CEO: Nuria Haltiwanger

Design-Build Contractor: FlatironDragados JV (50/50: Flatiron + Dragados, both ACS Group subsidiaries)

Public partners: Georgia Department of Transportation (GDOT); State Road and Tollway Authority (SRTA)

Federal lender: US Department of Transportation Build America Bureau (TIFIA loan)

Transit operator: MARTA (future BRT operations)

Deal counsel (lenders): Mayer Brown

Bond ratings: Baa3 (Moody’s); BBB+ (Kroll Bond Rating Agency) — both stable outlook

Engineering/design support: Parsons (50+ active GDOT contracts; 200+ employees in metro Atlanta)

Part of: Georgia Major Mobility Investment Program (MMIP)

Published 6th August 2025: An ACS-led consortium, SR 400 Peach Partners, has secured a significant public-private partnership (P3) financing with financial close on the SR 400 Express Lanes Project in Metro Atlanta. The consortium — consisting of ACS Infra (IRIDIUM), Acciona, and Meridiam — has obtained combined capital investment totaling $10.99B to fund the project.

This is followed by the completion of a $3.89 billion U.S. Department of Transportation (USDOT) Transportation Infrastructure Finance and Innovation Act (TIFIA) loan, and the successful issuance of $3.44 billion of tax-exempt private activity bonds (PABs).

Both financing transactions are record-breaking deals. The PABs offering, which received orders from over 90 investors and was approximately 1.7 times oversubscribed, is the largest bond financing on record for a U.S. highway asset. It also will be the largest municipal deal of the year. The TIFIA loan, being issued by the USDOT’s Build America Bureau, is the largest ever issued through the program for any asset to date.

Georgia’s First Revenue-Risk Managed Lanes Project

The State Road and Tollway Authority (SRTA) and Georgia Department of Transportation (GDOT) purchased the SR 400 Express Lanes Project. It is Georgia’s first — a revenue-risk managed lanes project where the private partner takes toll revenues on risk.

The consortium will build about 16 miles (25 kilometers) of new express toll lanes along the SR 400 corridor to improve mobility, reduce congestion, and enhance travel time reliability in and around metro Atlanta. After completing construction, the consortium will operate both the new express lanes and the existing free general-purpose lanes for 50 years.

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How the Project Is Financed

All three partners, ACS Infra, Acciona, and Meridiam, are investing 33.33% equity financed fully by letters of credit at financial close. Total investment includes:

A $3.89 billion TIFIA loan from the USDOT

$3.44 billion tax-exempt PABs

Estimated $4.6 billion design-build cost of construction

A $3.8 billion upfront concession payment to GDOT and SRTA

Construction Led by FlatironDragados

FlatironDragados, the 50/50 joint venture partnership between Flatiron (U.S. civil construction subsidiary of ACS Group) and Dragados (also a subsidiary of ACS Group), will be responsible for designing and constructing the project. They will spearhead the physical build-out of the express lanes infrastructure, from planning through ultimate delivery.

The consortium will add two managed lanes in each direction along 16 miles of SR 400 and will include additional managed lanes in selected locations as needed.

A Necessary Investment for a Growing Corridor

This SR 400 corridor is a critical north-south connector in Georgia, connecting Atlanta’s employment centers to housing in Fulton and Forsyth counties. Atlanta is the nation’s third-fastest-growing city and contains one of the world’s busiest airports. The corridor will once again experience growing travel demand when 144,000 new residents and 114,000 new jobs arrive by 2050.

The project is part of the Georgia Major Mobility Investment Program (MMIP) and serves to improve major road connections as well as alleviate congestion, particularly around SR 400 and I-285 areas.

A Milestone for the ACS Group

Financial close is an achievement and a culmination of over a year of collaboration with GDOT and SRTA,” stated Nuria Haltiwanger, ACS Infra Chairwoman and CEO, IRIDIUM CEO, and ACS Group Chief Investment Officer for Infrastructure.

“We are honored to be collaborating with the State of Georgia on a project that will provide badly needed relief from congestion in the metro Atlanta region while creating vast economic development, job creation, and long-term investment opportunities in the region.”

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SR 400 Express Lanes Project Factsheet

Project Overview

Location: Metro Atlanta, Georgia

Scope: 16 miles of new express toll lanes along SR 400 corridor

Contract Duration: 50 years (design, build, finance, operate, maintain)

Project Type: Revenue-risk managed lanes (Georgia’s first)

Financial Structure

Total Investment: $10.99 billion

Financing Components:

TIFIA Loan: $3.89 billion (largest ever issued)

Private Activity Bonds (PABs): $3.44 billion (largest highway bond financing in U.S. history)

Design-Build Costs: $4.6 billion (estimated)

Upfront Concession Fee: $3.8 billion (paid to GDOT/SRTA)

Key Partners

SR 400 Peach Partners:

ACS Infra (IRIDIUM) – 33.33% equity

Acciona – 33.33% equity

Meridiam – 33.33% equity

Public Partners:

Georgia Department of Transportation (GDOT)

State Road and Tollway Authority (SRTA)

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Design-Build Contractor:

FlatironDragados (50/50 joint venture between Flatiron and Dragados)

Project Details

New Infrastructure: Two managed lanes in each direction (additional lanes in select sections)

Existing Assets: Consortium will also operate/maintain existing free general-purpose lanes

Purpose: Improve mobility, reduce congestion, increase travel time reliability

Regional Impact

Growth Projections by 2050: 144,000 new residents, 114,000 new jobs in corridor

Strategic Importance: Key north-south route connecting Atlanta job centers to residential areas

Part of Georgia’s Major Mobility Investment Program (MMIP)

Record-Breaking Achievements

Largest TIFIA loan ever issued ($3.89B)

Largest highway bond financing in U.S. history ($3.44B PABs)

PABs offering was 1.7x oversubscribed with 90+ investors

Expected to be largest municipal bond deal of 2024/2025

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