Diagram 531.1 – Maximum Headroom of 12′-6” at Arch Bridge Ahead Warning Sign

The Diagram 531.1 sign is a warning traffic sign that alerts drivers to a low-arch bridge ahead with a restricted height clearance of 12 feet 6 inches. Featuring a red-bordered triangular shape with a black arch bridge symbol and height restriction, this sign is essential for preventing tall vehicles from colliding with the bridge structure.

This sign is commonly used in urban roads, rural routes, and railway bridge crossings, ensuring that HGVs (Heavy Goods Vehicles), buses, and high-sided vehicles take necessary precautions.

Key Features and Benefits

⚠️ Warns of Low-Height Bridges Ahead

• Alerts drivers that the arch bridge ahead has a restricted clearance of 12′-6”.
• Encourages drivers of tall vehicles to assess whether they can pass safely.
• Helps prevent dangerous bridge strikes and costly structural damage.

🚛 Prevents Accidents and Ensures Safe Route Planning

• Commonly placed before low railway bridges, old stone arch bridges, and underpasses.
• Ensures HGVs, buses, and vans have time to find an alternative route if necessary.
• Reduces the risk of vehicles becoming stuck or colliding with the bridge structure.

👀 Highly Visible and Easy to Recognize

• Red-bordered triangular design conforms to UK warning sign standards.
• Black bridge symbol with height restriction ensures clear recognition.
• Made with retroreflective materials for visibility day and night.

Where is the Diagram 531.1 Sign Used?

The Diagram 531.1 sign is installed in locations where low-clearance arch bridges are present. Common placements include:

• Railway bridge underpasses 🚆 – Preventing high vehicles from striking bridges.
• Historic arch bridges 🏰 – Protecting old structures from accidental damage.
• Urban roads with height-restricted tunnels 🏙️ – Ensuring only permitted vehicles pass.
• Narrow country lanes 🌳 – Informing drivers of limited headroom ahead.
• Multi-level roadways and subways 🛣️ – Where clearance restrictions apply.

By clearly marking height-restricted routes, this sign helps prevent bridge strikes and serious traffic disruptions.

Understanding Height Restriction Signs

The Diagram 531.1 sign is part of a series of height restriction and clearance warning signs that inform drivers of road limitations. It works alongside:

✅ Diagram 530 – “Low Bridge Ahead” (general warning of low-clearance structures).
✅ Diagram 629.2 – “Mandatory Height Restriction” (used where over-height vehicles are prohibited).
✅ Diagram 816.1 – “Advance Height Warning Sign” (providing alternative routes for tall vehicles).

These signs improve driver awareness and reduce the risk of vehicle-bridge collisions.

Durability and Compliance

To ensure long-lasting performance and compliance with UK traffic regulations, our Diagram 531.1 sign is made from high-quality, durable materials:

✔️ Retroreflective coating for night-time visibility 🌙
✔️ Weatherproof aluminum or composite material 🌧️
✔️ Rust and corrosion-resistant for outdoor durability 🏗️
✔️ Available in multiple sizes for different road environments 📏
✔️ Fully compliant with UK TSRGD regulations ✅

This sign is essential for local councils, railway authorities, and road safety planners managing low-clearance bridge zones.

Who Needs This Sign?

The Diagram 531.1 sign is widely used by:

✅ Local councils and highway authorities – Preventing bridge strikes in low-clearance areas.
✅ Railway and infrastructure agencies – Protecting railway bridges from accidental collisions.
✅ Construction and road maintenance teams – Installing height restriction warnings on new roads.
✅ Logistics and freight companies – Helping HGV drivers plan safe, unrestricted routes.

By placing this sign at strategic locations, authorities can reduce accidents, prevent costly bridge damage, and improve traffic safety.

Summary

✔️ Warns drivers of a maximum headroom of 12′-6” at an arch bridge ahead 🚛
✔️ Encourages high-sided vehicles to find alternative routes ⚠️
✔️ Used near railway bridges, tunnels, and historic archways 🚆
✔️ Highly visible with reflective materials for night-time use 🌙
✔️ Fully compliant with UK road regulations (TSRGD) ✅

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Additional resources:

Driving rules

• The Highway Code
• Legal obligations of drivers and riders