Understanding the UK's GG 903 Customer Service Standard for Diversion Routes During Unplanned Events

When unexpected road closures occur on motorways and trunk roads, managing traffic effectively becomes critical. In the United Kingdom, GG 903 — the Customer Service Standard for Diversion Routes for Unplanned Events — establishes a clear framework for planning and managing diversion routes.

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This guide provides a comprehensive explanation of GG 903, its purpose, scope, and how it ensures better experiences for road users.

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What is GG 903?

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GG 903 is a part of the UK's Design Manual for Roads and Bridges (DMRB), published by Highways England in 2020. It outlines customer service standards that must be followed when planning and implementing diversion routes during unplanned events, such as accidents, emergency roadworks, or unexpected incidents.

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The objective of GG 903 is to:

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• Ensure safe, continuous journeys for motorists.

• Minimise disruptions during closures.

• Build customer trust in diversion management.

• Support legal obligations under the Infrastructure Act 2015 and Traffic Management Act 2004.

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Why GG 903 Matters in the UK

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Road closures, whether caused by accidents or severe weather, can create confusion, delays, and frustration. GG 903 plays a critical role by ensuring:

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• Pre-approved diversion routes are available for all traffic types, including heavy goods vehicles.

• Routes are safe, suitable, and clearly signed.

• Stakeholders such as local authorities are involved in planning.

• Road users are kept informed to make better travel decisions.

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In essence, GG 903 is about prioritising the customer experience during difficult and unexpected travel situations.

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Scope of GG 903

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GG 903 applies specifically to:

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• Motorways and all-purpose trunk roads in England.

• Full carriageway closures due to unplanned incidents.

• Both the establishment of new diversion routes and the review of existing ones.

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It does not cover planned events, nor the real-time operational deployment during an emergency, which is handled separately.

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Key Definitions in GG 903

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To fully understand the standard, some important definitions include:

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• Diversion Route: A pre-signed alternative path for traffic during an unplanned closure.

• Secondary Diversion Route: An alternative route for specific vehicle classes or strategic needs.

• Contingency Plan: Pre-agreed fallback arrangements if the primary diversion is unavailable.

• Closure: A complete restriction of traffic requiring a diversion.

• Unplanned Disruption: Any unforeseen interruption to free-flowing traffic.

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Major Requirements of GG 903

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The standard details several important requirements:

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1. Diversion Routes for All Traffic

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Diversion routes must cater to all vehicle types unless a restriction is necessary and justified.

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2. Agreements with Traffic Authorities

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Diversion plans must be discussed, agreed upon, and signed off by relevant local authorities and emergency services.

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3. Annual Reviews and Engagement

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Authorities must engage with stakeholders every year to review routes, discuss improvements, and address new challenges.

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4. Safety Risk Assessments

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New diversion routes require a formal safety risk assessment to identify hazards and ensure safe usability.

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5. On-Road Inspections

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Physical inspections must be conducted to verify that the diversion routes meet customer service standards.

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Classifying Diversion Routes

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Diversion routes are categorized based on their compliance:

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• Class 1a: Fully compliant, suitable for all vehicles.

• Class 1b: Mostly compliant, minor improvements pending.

• Class 2a: Suitable only for light vehicles; no issues.

• Class 2b: Suitable only for light vehicles, pending improvements.

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Classification helps in making real-time decisions during emergencies.

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Diversion Signage Standards

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Proper signage is critical to successful diversion management:

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• Signs must be placed at every key decision point.

• Signs must be visible both day and night.

• Use of standardized diversion symbols is required.

• Repeater signs should offer reassurance to drivers along the route.

• Signage conflicts must be resolved to avoid driver confusion.

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Signage quality directly impacts customer confidence during diversions.

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Additional Key Considerations

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Physical Attributes of the Route

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Routes must be able to accommodate vehicles of required height, weight, and width without undue risk.

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Travel Time Documentation

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Expected travel time on the diversion route must be recorded for comparison with delays from the original closed route.

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Welfare Facilities

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Access to essential services like fuel stations, rest areas, and food outlets must be considered when choosing a route.

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Toll Roads

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Using toll roads as part of a diversion requires specific agreements and must not add unplanned costs to road users unless necessary.

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Environmental and Community Impacts

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Diversion plans must account for local community disruption, environmental zones, and vulnerable road users.

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Inspection and Review Process

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GG 903 mandates a robust four-stage inspection process:

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1. Desk-Based Audit: Reviewing existing route data.
2. Workshops with Stakeholders: Joint discussion sessions with authorities.
3. On-Road Inspections: Physically driving and assessing the route.
4. Classification and Documentation: Assigning route categories and planning improvements.

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Regions are encouraged to inspect at least 20% of their diversion routes annually.

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Conclusion

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The UK's GG 903 Customer Service Standard ensures that road users experience the least disruption possible during unplanned events. By focusing on pre-planned routes, clear signage, risk assessments, and stakeholder collaboration, GG 903 transforms emergency diversion management into a customer-focused operation.

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Whether you are a highway engineer, traffic planner, or part of an emergency services team, understanding and applying GG 903 is critical to maintaining trust, safety, and efficiency across the UK's road network.

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