UK’s GD 904: Safe Speed Limits and 60mph in Road Works

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Speed limits play a crucial role in ensuring road safety and efficiency, especially in work zones where temporary traffic management is required. GD 904, published by Highways England, provides comprehensive guidelines on the use of highest safe speed limits, including 60mph speed limits at road works, to improve traffic flow while maintaining safety for road users and workers.

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This standard is a response to findings that higher speed limits (when safe) can reduce congestion, enhance driver compliance, and lower instances of risky driving behavior. Let’s explore how GD 904 is transforming speed management in the UK’s road work zones.

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What is GD 904?

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GD 904 is part of the Design Manual for Roads and Bridges (DMRB) and outlines the requirements for setting the highest safe speed limits on motorways and all-purpose trunk roads. It includes specific advice on implementing 60mph speed limits in road works to balance safety and efficiency.

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Objectives of GD 904

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✔ Maximize road capacity while maintaining safety.
✔ Reduce congestion by allowing higher speeds where feasible.
✔ Enhance driver compliance with realistic speed limits.
✔ Ensure safety for road workers and road users.
✔ Provide a consistent framework for temporary speed management.

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Why Use 60mph in Road Works?

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Traditionally, road work zones in the UK have used 50mph or lower speed limits to ensure worker and driver safety. However, research and trials conducted by Highways England indicate that:

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✔ Drivers comply better with 60mph speed limits than 50mph ones.
✔ Traffic flows more smoothly, reducing delays and frustration.
✔ HGVs maintain safer distances, reducing tailgating risks.
✔ Journey times improve, benefiting road users and businesses.

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Key Insight: Not all road works will permit 60mph. GD 904 ensures that higher speed limits are applied only when safety is not compromised.

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How is the Highest Safe Speed Determined?

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1. Risk Assessments

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Before setting a speed limit, engineers conduct a safety risk assessment to evaluate:
✔ Road layout and visibility – ensuring adequate sight distance.
✔ Traffic volume and mix – including the presence of HGVs and vulnerable road users.
✔ Work zone characteristics – such as barrier protection and worker proximity.
✔ Historical accident data – to assess potential risks.

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2. Traffic Management Design

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GD 904 recommends designing temporary traffic management (TTM) to accommodate the highest safe speed possible. This means:
✔ Using clear signage and road markings to guide drivers.
✔ Installing barriers and protective measures for workers.
✔ Ensuring lane widths and road geometry support higher speeds.

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3. Speed Limit Adjustments by Section

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Instead of one fixed speed limit across all work zones, GD 904 allows for variable limits based on conditions. For example:
🚧 Entry & Exit Zones – May require lower speeds (e.g., 50mph).
🚗 Main Work Area – Can allow 60mph if risks are controlled.
⚠ Complex Intersections or Lane Mergers – Require careful speed evaluations.

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Implementation & Compliance

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National Application of GD 904

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GD 904 applies to all motorways and trunk roads in England, with additional National Application Annexes for:

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• Northern Ireland
• Scotland (not currently implementing GD 904)
• Wales
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Temporary Speed Limit Signage

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✔ Must follow Traffic Signs Manual Chapter 8 guidelines.
✔ Should be clearly visible and consistent throughout work zones.
✔ Electronic Variable Message Signs (VMS) may be used for real-time updates.

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Legal & Contractual Considerations

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• GD 904 is part of Highways England’s works specifications.
• All projects must comply with GG 101: Introduction to the DMRB and GG 104: Safety Risk Assessment.
• Contractors must provide evidence for lower speed limits if 60mph is deemed unsafe.

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Conclusion

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GD 904 is revolutionizing speed management in UK road works by allowing 60mph speed limits where safe to do so. This approach ensures:

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✔ Smoother traffic flow and reduced congestion.
✔ Better compliance with speed limits.
✔ Safer conditions for both drivers and road workers.

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With data-driven risk assessments and improved traffic management, the UK’s roads are becoming safer and more efficient, even during construction projects.

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