DIAGRAM 820B

Diagram 820B – Road Unsuitable for Wide Vehicles

The Diagram 820B road sign is used to indicate that a road is unsuitable for wide vehicles, helping to prevent access by oversized or large vehicles that may struggle to pass through safely. This sign is crucial for road safety, especially in areas with narrow lanes, low bridges, or sharp bends where wide vehicles could cause congestion or accidents.

Traffic signs such as Diagram 820B play a significant role in managing road use and ensuring drivers are well-informed about potential hazards. Understanding the meaning, usage, and importance of this sign can help both road users and local authorities maintain smooth traffic flow and prevent dangerous situations.

Sign Meaning and Usage

The Diagram 820B sign is a blue rectangular information sign with white text, making it easy to read and understand. It serves as a clear indication that the road ahead is not suitable for wide vehicles, often due to physical constraints or road design features that make navigation difficult for larger transport.

Key purposes of this sign include:

• Preventing large vehicles from entering roads where they might get stuck or obstruct traffic,
• Providing advance notice to HGV drivers to find alternative routes,
• Enhancing road safety by reducing the risk of collisions or blockages,
• Protecting road infrastructure from potential damage caused by oversized vehicles.

This sign is typically placed at entry points to restricted roads, near junctions, or in areas where alternative routes are available for larger vehicles.

Why is Diagram 820B Important for Road Safety?

1. Reduces Traffic Disruptions – Ensuring wide vehicles do not enter unsuitable roads prevents traffic congestion, blockages, and potential accidents.

2. Prevents Damage to Road Infrastructure – Narrow roads, weak bridges, and height-restricted areas can suffer damage if large vehicles attempt to pass through. The sign helps protect these structures.

3. Improves Navigation for HGVs and Large Vehicles – By providing early warnings, drivers of wide vehicles can plan their routes effectively and avoid problematic areas.

4. Increases Safety for All Road Users – Narrow roads can pose a hazard if wide vehicles try to navigate through, increasing the risk of collisions, breakdowns, or reversing hazards.

Placement and Compliance Regulations

The Diagram 820B sign is regulated under the Traffic Signs Regulations and General Directions (TSRGD) in the UK. Proper placement ensures that drivers receive adequate warnings before committing to a route.

To be effective, this sign must be:

• Placed at key decision points, such as road junctions or motorway exits,
• Clearly visible to approaching drivers,
• Maintained regularly to ensure readability,
• Used in conjunction with other directional signs to guide wide vehicles towards alternative routes.

Local councils and highway authorities are responsible for ensuring these signs are placed correctly in locations where wide vehicles could face difficulties.

Key Considerations for Drivers

• Check vehicle dimensions before planning routes to avoid restrictions.
• Follow diversion signs if a road is marked as unsuitable for wide vehicles.
• Be aware of other road users, especially in narrow or rural areas.
• Use satellite navigation systems designed for HGVs to avoid problematic routes.
• Report missing or damaged signs to local authorities to maintain road safety.

Driving rules

• The Highway Code

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