Top 10 Fasteners Used in Bridge and Highway Construction

Bridge and highway construction projects require far more than just concrete and steel—they rely on an extensive range of structural fasteners to ensure safety, compliance, and long-term durability under extreme conditions. From anchoring traffic light poles to holding together massive steel girders, each fastener has a specific purpose and standard behind it.

In this article, we’ll walk through the top 10 fasteners used in bridge and highway construction, covering their functions, materials, coatings, and common specifications.

Purpose: Foundation anchoring for light poles, sign structures, handrails, and bridge supports

Common Standards: ASTM F1554 Grade 36, 55, or 105

Coatings: Hot-dip galvanized (HDG) for outdoor use

F1554 anchor bolts are embedded in concrete foundations and provide critical structural anchoring for vertical supports. Their strength grade must match project load requirements, and HDG coatings offer corrosion protection in outdoor environments.

Purpose: Foundation rods, embedded steel, structural bracing

Common Standards: ASTM A193 B7, A307, or custom cut-length rods

Coatings: HDG or plain steel depending on application

Threaded rods are highly versatile in bridge construction. They’re often used in tension connections, form tie systems, or in post-installed anchor assemblies. Engineers select diameter and grade based on tensile loading and anchorage depth.

Purpose: Primary structural steel connections

Common Standards: ASTM A325 (Class 1/3), ASTM A490

Coatings: HDG, mechanical galvanizing

Heavy hex bolts are the workhorses of bridge superstructures. With a larger head and nut interface, they provide better bearing on structural plates and are typically paired with hardened F436 washers and A563 nuts.

Purpose: High-strength friction connections, splice plates, gussets

Common Standards: ASTM A325 or A490

Coatings: HDG, plain or weathering steel (Type 3)

Structural bolts are often used in critical load-path joints that require high clamping force. They’re essential in bolted moment frames, diagonal bracing, and steel box girder assembly. Some use tensioning tools for controlled preload.

Purpose: Mating component for structural bolts and anchor bolts

Common Standards: ASTM A563 (Grade DH or C)

Coatings: Must match bolt coating (e.g., HDG or plain)

These nuts have thicker walls to withstand high torque without deforming. For HDG bolts, oversized HDG nuts are typically required to account for coating thickness.

Purpose: Distribute load, prevent embedment under bolt heads/nuts

Common Standards: ASTM F436

Coatings: HDG, plain, or zinc-plated

Washers help prevent localized deformation and ensure uniform load transfer across bolted joints. In some bridge decks or bearing plate connections, larger square plate washers may be specified.

Purpose: Embedded anchorage in concrete bases

Common Standards: ASTM F1554 (bent per project specs)

Coatings: HDG for exposed ends

These are L-shaped or J-shaped bolts used in cast-in-place concrete to resist pull-out forces. Commonly used in bridge piers, base plates, and highway signage structures.

Purpose: Support for utility piping, bridge-mounted conduits

Common Standards: ASTM A307, custom thread lengths

Coatings: HDG, sometimes epoxy-coated

U-bolts are often custom-bent to fit around pipes or conduit brackets. They secure mechanical systems to bridge undersides or concrete walls, especially in urban infrastructure.

Purpose: Connect timber bridge decking, railings, and boardwalks

Common Standards: ASTM A307B or custom hardware

Coatings: Hot-dip galvanized for moisture resistance

Timber bolts feature wide heads (often domed or square-shouldered) that eliminate the need for washers and provide resistance to pull-through in wood structures. They are ideal for composite bridge decks and wooden pedestrian spans.

Purpose: Fastening highway guardrails, safety barriers, and crash systems

Common Standards: AASHTO M180, ASTM A307

Coatings: HDG standard

These bolts typically have round or mushroom heads for safety and tamper resistance. Used widely in barrier systems, they’re designed for fast installation and high vibration resistance.

Most bridge and highway fasteners are exposed to rain, de-icing chemicals, and coastal moisture—making corrosion protection critical. Hot-dip galvanizing (HDG) remains the most common finish for long-term durability. In special cases, weathering steel (Type 3) or stainless steel may be specified.

To avoid thread interference, always match nuts and washers with the same coating system as bolts.

Major infrastructure projects often require:

• ASTM, ISO, or EN-compliant hardware
• Mill Test Reports (MTRs) with full traceability
• CE marking for European-bound exports
• Third-party inspection records for public tenders

At TUHU Fasteners, we support global contractors with custom bolt manufacturing, certified materials, and technical documentation for cross-border projects.

Selecting the correct fasteners in bridge and highway construction isn’t just about size or strength—it’s about using application-specific hardware that meets the performance, durability, and safety demands of infrastructure work.

Explore TUHU’s Infrastructure-Grade Fasteners

We offer anchor bolts, headed bolts, threaded rods, nuts, washers, and more—manufactured to ASTM and ISO standards, available with HDG and custom coatings.

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