Historic truss reinforcement
The approximately 295-ton package included new reinforcement interfacing with the original built-up, riveted trusses.
LocationNew York City, New York
Client and fabricatorL&M Fabrication and Machine
Steel in our detailing packageApproximately 295 tons
Completion2021
Project overview
Connecting 1912 steelwork with a 21st-century transportation hub.
Moynihan Train Hall transformed the landmark James A. Farley Post Office Building into a 255,000-square-foot extension of New York Penn Station.
At the center of the project are three original 150-foot steel trusses that once supported the roof of the building’s mail sorting room. The trusses were uncovered, reinforced and incorporated into the support system for four new arched skylights rising 92 feet above the concourse floor.
Working for L&M Fabrication and Machine, our team provided steel detailing for an approximately 295-ton reinforcement package.
Existing steel removed, modified and reinforced across the Farley Building.
The complete Moynihan redevelopment extended well beyond our individual detailing package.
Across the overall project:
- approximately 1,000 tons of existing steel were removed,
- approximately 4,000 tons were modified,
- approximately 6,000 tons of new steel were added.
These figures describe the complete redevelopment and should not be confused with our 295-ton detailing scope.
New access points developed above active rail infrastructure.
The complete redevelopment included the Main Train Hall, Midblock Hall and West End Concourse.
Eleven new escalators provide access between the train hall and the platforms below. Creating these openings required modifications to existing deep plate girders and the introduction of new transfer framing.
These elements provide important context for the scale and complexity of the complete project, but they should not be presented as part of our 295-ton package unless confirmed by internal documentation.
Project team and technical details
- Owner
- New York State / Empire State Development
- Primary scope
- Structural steel reinforcement detailing
- Existing structure
- James A. Farley Post Office Building
- Original construction
- 1912, with 1933 annex
- Primary historic elements
- Three 150-foot riveted steel trusses
- New architectural feature
- Four arched skylights rising 92 feet above the concourse
- Structural engineer
- Severud Associates
- Architect
- Skidmore, Owings & Merrill
- General contractor
- Skanska USA
- Project-wide connection systems
- Field-welded shear plates, bolted moment connections and SidePlate™ connection designs
Detailing scope
Structural steel detailing scope.
Heavy plate box beams
Built-up box sections along the existing truss top chords provided reinforcement beneath the new skylight structure.
Rivet-clearance filler plates
Custom plate geometry and hole patterns allowed new steel to fit around the existing rivet heads.
Welded reinforcement interfaces
The package communicated heavy plates, welded reinforcement and relationships between new components and historic steel.
Fabrication and field-assembly information
Detailing for L&M Fabrication and Machine focused on accurately fitting the reinforcement to the existing structural framing.
Model to field
From coordinated geometry to the project on site.
01 / Coordinated model
02 / Fabrication & fieldTechnical complexity
Fitting new reinforcement around existing rivet heads.
Fitting around century-old rivets
Existing rivet heads prevented reinforcement from meeting a flat surface. Custom clearance and filler plates needed precise hole positioning.
Built-up reinforcement against existing steel
Heavy plate box beams and welded components had to be represented accurately at their interfaces with historic riveted sections.
Changed bracing and skylight requirements
Removing surrounding roof framing changed the original trusses’ bracing conditions. Reinforcement supported their new role beneath the arched skylights.
Our approach
Built-up box sections developed around historic conditions.
The truss reinforcement included steel box beams positioned along the tops of the existing trusses.
The box beams were assembled from heavy steel plates and concealed beneath the new skylight structure. Within the structural design, they provide lateral support and transfer loads toward the ends of the trusses.
The detailing work required precise representation of:
- heavy plate components,
- filler and clearance plates,
- existing riveted built-up sections,
- welded reinforcement,
- interfaces between new and existing steel,
- fabrication and field-assembly requirements.
Historic trusses supporting a new architectural centerpiece.
Four independent arched skylight modules enclose the main train hall. Their lightweight steel grids follow the profile of the existing truss top chords and rise approximately 92 feet above the concourse.
The reinforced historic trusses form the structural basis for the new roof system, allowing the original steelwork to remain visible as part of the completed architecture.
Our package focused on reinforcement at the interface between the original trusses and the new structural requirements.
Historic riveted framing combined with modern connection technology.
The broader Moynihan Train Hall redevelopment brought together structural steel from the building’s 1912 and 1933 construction phases with current AISC requirements and modern connection systems.
Project-wide connection solutions included:
- field-welded shear plates,
- bolted moment connections,
- SidePlate™ connection designs,
- welded reinforcement of existing built-up members,
- new steel fitted around historic riveted connections.
Our 295-ton detailing package focused on reinforcement steel fabricated by L&M Fabrication and Machine, including components developed to interface with the existing structural framing.
SidePlate™ was used within the broader redevelopment; its inclusion in our specific package has not been independently confirmed.
Project result
Historic structural steel transformed into a defining architectural feature.
Moynihan Train Hall opened on January 1, 2021.
The reinforced trusses, originally concealed within the roof of the postal facility, are now exposed above the main concourse. They support the modern skylight system while preserving visible evidence of the Farley Building’s original steel construction.
The project demonstrates how carefully developed reinforcement can extend the service of historic structural steel while adapting it to a new architectural and operational purpose.