Bridge Structural Engineering in NYC:
Erection Plans, Demolition & Inspection

Bridge Structural Engineering in New York City

New York City is home to over 2,000 bridges of varying types, materials, and ages — from the iconic suspension bridges of the East River to thousands of smaller municipal bridges over highways, railroads, and waterways. Bridge work in NYC involves a complex regulatory environment with multiple governing agencies, strict safety requirements, and the ever-present challenge of working in a dense urban environment with active traffic, pedestrian loads, and marine traffic below.

Structural engineers working on NYC bridge projects must navigate:

• NYCDOT Bridge Inspection Standards — all city-owned bridges are inspected under the NYCDOT Bridge Inspection Unit
• NYSDOT Standards — state bridges on state-controlled roadways in NYC follow NYSDOT requirements
• NYC DOB involvement — structural work in DOB-regulated areas (private property bridges, pedestrian bridges on private property) requires DOB permits
• MTA/Transit Authority jurisdiction — bridges over or adjacent to subway infrastructure require MTA coordination
• USACE and Coast Guard — any work on or over navigable waterways requires Army Corps of Engineers permits and USCG notifications

Bridge Erection Plans in NYC

A bridge erection plan (BEP) is a PE-sealed set of documents that defines the safe sequence of construction for a bridge or bridge component. Under OSHA 29 CFR 1926 Subpart R (Steel Erection) and the NYC DOB requirements for temporary work, erection plans are mandatory for most bridge construction operations.

What Bridge Erection Plans Cover

• Phased stability analysis — the structure must be structurally stable at every construction phase, not just when complete. BEPs show temporary supports, guy wires, and bracing requirements for each stage
• Falsework design — temporary support structures (falsework) under concrete deck forms or steel during placement must be PE-designed
• Crane pick sequencing — the sequence of placing individual steel members or precast concrete girders must be analyzed to ensure the partially completed structure doesn't overstress any element
• Connection design during erection — the temporary connections used during erection (drift pins, erection bolts, tack welds) must be sufficient for construction-phase loads
• Equipment positioning — crane outrigger loads and positioning relative to bridge abutments and substructure must be analyzed

Types of Bridge Construction in NYC Requiring Erection Plans

• Steel plate girder bridge replacement (common on NYC highway overcrossings)
• Precast concrete girder placement
• Steel truss rehabilitation and girder replacement
• Pedestrian bridge installation over active roadways
• Temporary vehicular bridges during permanent bridge reconstruction

Bridge Demolition & Removal in NYC

Bridge demolition requires as much (or more) structural engineering as new construction. A demolition plan must account for the same structural stability requirements — the partially demolished structure must remain stable at each stage — but with the added complexity of unknown material condition, corroded connections, and the need to avoid progressive collapse.

Key Elements of a Bridge Demolition Plan

• Sequential demolition analysis — analysis of stability at each demolition step; certain members may be "keystone" elements whose premature removal causes progressive collapse
• Temporary shoring — bridge elements that can't be self-supporting during partial demolition require temporary shores or outrigger supports
• Cutting sequence — for concrete bridges, saw-cut sequences must avoid inducing bending in sections beyond their remaining capacity
• Marine demolition — for waterway bridges, demolished members must be controlled to prevent them from falling into the water or striking marine assets; barges or cofferdams may be required
• Hazardous materials — older bridges (pre-1980) may contain lead-based paint requiring OSHA 1910.1025 / 1926.62 lead abatement protocols before or during demolition
• Traffic protection — work over active roadways requires engineered protection systems (bridge protection frames, catch platforms) per NYCDOT Traffic Operations

Cofferdam & Water Diversion Design

Bridge foundation work in or adjacent to bodies of water frequently requires a cofferdam — a temporary retaining structure that excludes water from the work area and allows construction to proceed in a relatively dry excavation. Cofferdams are also used for bridge pier rehabilitation, scour repair, and abutment reconstruction.

Cofferdam Types Used in NYC

• Sheet pile cofferdams — interlocking steel sheet piles driven into the riverbed; most common for depths up to 25–30 feet in NYC waterways. Double-wall cofferdams (two parallel sheet pile walls filled with granular material between them) are used for larger excavations or higher water pressures
• Braced cofferdams — sheet pile walls internally braced with horizontal waling beams and struts; the structural engineer designs braces for hydrostatic and earth pressure loads
• Cellular cofferdams — circular cells of sheet piling filled with granular material for very wide cofferdam enclosures or where internal bracing is impractical
• Caisson cofferdams — rarely used in modern NYC practice; pre-built concrete boxes sunk into position, used historically for major bridge foundations

NYC Waterway Permitting for Cofferdam Work

Any work that modifies, obstructs, or fills in a navigable waterway in New York City requires:

• Section 404 Permit (U.S. Army Corps of Engineers) — for discharge of dredged or fill material
• Section 10 Permit (USACE) — for work in navigable waters
• NYSDEC Section 401 Water Quality Certification
• NYC Waterfront Revitalization Program (WRP) consistency review
• USCG Coastal Zone Management notification for navigable waterways

Temporary cofferdams that are entirely removed upon completion of the substructure work are typically addressed under Nationwide Permits (NWP 3 or NWP 14), significantly streamlining the permitting process.

Bridge Structural Assessment & Inspection

Structural assessment of existing bridges goes beyond routine inspection to provide a detailed engineering evaluation of the bridge's load capacity, condition, and remaining service life. This is typically required when:

• A bridge is being considered for increased live loads (heavier vehicles, increased pedestrian load)
• Unusual cracking, corrosion, or deformation has been observed during routine inspection
• A bridge has been struck by an oversized vehicle or has experienced a collision, flood, or scour event
• A bridge is approaching or has exceeded its design life
• The bridge is being purchased, sold, or transferred and a condition report is needed for due diligence

Bridge Assessment Methods

• Visual inspection — identification of visible defects (cracking, spalling, corrosion, deformation) by qualified bridge inspectors
• Non-destructive testing (NDT) — sounding, ground-penetrating radar (GPR), half-cell potential testing for rebar corrosion, ultrasonic thickness testing for steel members
• Load rating analysis — AASHTO MBE load rating procedures to determine the bridge's legal load capacity (rating factor)
• Finite element analysis — 3D structural modeling for complex bridge geometries or when simplified equations are insufficient

Temporary Bridges & Access Structures

Temporary bridges are used during construction to maintain access while a permanent bridge is being replaced, or to provide construction access over obstacles. They include:

• Bailey or modular steel panel bridges for temporary vehicular access
• Timber trestle bridges for construction equipment access
• Temporary pedestrian bridges during sidewalk or path closures
• Construction access bridges over trenches, excavations, or waterways

Temporary bridges in NYC require PE-sealed structural drawings (erection plan), a temporary construction permit from NYC DOT (for bridges over public streets), and may require MTA or Port Authority coordination if over their infrastructure.

NYC Bridge Governing Agencies

Permits & Approvals for Bridge Work in NYC

Bridge work in New York City can involve up to a dozen separate permits and approvals depending on the bridge location, type, and scope of work. Key permits include:

• NYC DOT street opening / highway work permit
• NYC DOT traffic control plan approval
• NYC DOB structural work permit (for DOB-regulated bridges)
• USACE Section 404 / Section 10 permit (waterway work)
• USCG bridge alteration permits (for bridges over navigable waters)
• NYSDEC Section 401 water quality certification
• State Historic Preservation Office (SHPO) Section 106 review (for historic bridges)

At Asvakas Engineering, our bridge team has experience navigating the multi-agency permitting process for bridge projects of all sizes across NYC and the tristate region.

Frequently Asked Questions