Case Study — MTA Contract HC-07
Hugh Carey
Tunnel
Design-Build Replacement of Fan Motors & Installation of the First High-Pressure Water Mist Fire Suppression System in North America
$72M
Contract Value
104
Custom Motors
6,000′
Suppression Coverage
2×
ACEC Awards
Project Overview
Modernizing one of NYC’s most critical infrastructure arteries
The Hugh Carey Tunnel — originally opened in 1950 as the Brooklyn-Battery Tunnel — is the longest continuous underwater vehicular tunnel in North America, carrying over 54,000 vehicles daily between Brooklyn and Lower Manhattan.
Under MTA Contract HC-07, Navillus served as General Contractor on one of the most technically demanding design-build infrastructure projects in the New York metro area — replacing the tunnel’s aging ventilation fan motors and engineering a first-of-its-kind fire suppression system, all while keeping the tunnel operational for daily traffic.
Navillus managed all phases from design through procurement and installation, coordinating a team of 80–100 professionals across multiple trades and working through some of the most challenging conditions in tunnel construction — including the onset of the COVID-19 pandemic.
Project Snapshot
Key project data at a glance
Client / Owner
MTA Bridges & Tunnels
Project Type
Transportation Infrastructure — Design-Build
Location
160 Hamilton Ave, Brooklyn, NY
Duration
December 2018 – October 2021
Engineers
Shenoy (MEP) · SGH (Structural)
Architect
Wai Tong Chan
Key Consultants
Mott McDonald · JW Mooney Acoustics · Fogtec · WMS
Key Subcontractor
KG Power
Custom Motor Design & Manufacturing
Louis Allis
Team Size
80–100 professionals, consultants & subcontractors
Navillus Team On Site
Fire Suppression Testing
Equipment Delivery
Challenges & Solutions
First-of-its-kind engineering in one of NYC’s most constrained environments
01
Custom Fan Motor Design with No Existing Documentation
Challenge
The tunnel’s original fan motors — critical first-line-of-defense systems in a tunnel fire — had no surviving design documentation. New motors needed to meet rigorous performance parameters to maintain code compliance.
Solution
Working with subcontractor KG Power, Navillus removed approximately 24 existing fan units and sent them for comprehensive laboratory testing. The resulting data informed the design and manufacture of 104 new custom motors rated up to 300 HP, installed across all four ventilation buildings.
02
First-in-North America Fire Suppression System
Challenge
Design and install a high-pressure water mist fire protection system spanning 3,000 feet in each tunnel tube — never before deployed in North America, and the first globally for this ventilation configuration.
Solution
Navillus led extensive design development including full-scale mockups and live testing within the tunnel to validate performance. International specialists coordinated system components from Germany.
03
Working Inside an 80-Year-Old Active Tunnel
Challenge
Primary work areas — the exhaust air plenums above the tunnel roadways — were confined, difficult to access, and required night-time roadway closures to maintain traffic flow.
Solution
Rigorous confined space evacuation procedures, comprehensive rigging and fall protection protocols, and carefully scheduled overnight installations. Fan motors were delivered by barge to Governors Island.
04
NFPA 502 Compliance in a Legacy Structure
Challenge
Achieving NFPA 502 compliance in a structure built in the 1940s presented significant engineering constraints. Standard fire testing approaches were not feasible.
Solution
The team deployed advanced Computational Fluid Dynamics (CFD) analysis combined with equivalency analysis benchmarked against the SOLIT fire testing series — a first for regulatory approval in a North American tunnel.
Fan Motor Modernization
Before
→
After
Engineering Innovations
Pioneering techniques that set new industry standards
- High-pressure crimped stainless steel pipe fittings to reduce welding in confined tunnel spaces
- High-pressure flexible hoses to address thermal expansion and complex installation constraints
- Pre-assembled electrical panels to streamline valve control and reduce on-site installation time
Tunnel Systems Installation
Results & Outcomes
Delivered on time. On budget. Zero compromises.
On Time
Delivered on schedule despite pandemic disruptions
On Budget
No cost overruns
Award-Winning
Dual ACEC recognition
✓
Full ventilation and fire life-safety systems modernized with zero disruption to daily tunnel operations
✓
Achieved NFPA 502 compliance in a legacy structure through innovative engineering approaches
✓
Outstanding safety record throughout entire project duration
✓
Maintained full project schedule through the COVID-19 pandemic
✓
Formal letter of recommendation from MTA Bridges & Tunnels
✓
Direct follow-on $138M contract awarded based on project performance
Awards & Recognition
Industry-recognized excellence
Platinum Award for
Excellence in Engineering
Excellence in Engineering
American Council of Engineering Companies · 2024
Special Projects Award
American Council of Engineering Companies · 2023
What Came Next
The success of HC-07 positioned Navillus to compete for even larger opportunities
MTA Bridges & Tunnels awarded Navillus a new $138 million design-build contract through competitive procurement to extend the fire suppression system within the Hugh Carey Tunnel and to design and install a new system in the Queens Midtown Tunnel. The experience gained on HC-07 demonstrated that Navillus was the most qualified, responsive, and responsible bidder for the job.
$138M
Design-Build Contract Won