11/11/2025
Highway bridges are a critical component of Britain’s transport infrastructure, enabling the flow of goods and people across natural and man-made obstacles. Bridge closures can cause major disruption to local economies and supply chains. According to the RAC Foundation and ADEPT (2024), almost 3,000 council-maintained road bridges in Great Britain are currently classed as ‘substandard’—meaning they cannot safely carry the heaviest lorries on the road. This not only restricts logisticsroutes but also raises concerns over long-term safety and resilience.
This article provides a review of the latest independent findings, analyses the structural and financial implications of the current state of our bridge stock, and explores solutions through modern engineering approaches and strategic asset management.
Scale and classification of substandard bridges
Current data indicates that local authorities across Great Britain manage approximately 72,000 road bridges (RAC Foundation, 2019). Of these, 3,090 bridges (4.3%) are classified as substandard. The definition of substandard in this context refers to bridges that cannot safely support the heaviest standard vehicles, typically 44-tonne articulated lorries, which are the backbone of commercial freight traffic. Recent analysis by the Institution of Civil Engineers reinforces this concern, highlighting that almost 3,000 bridges in the UK are currently substandard and unable to accommodate the heaviest vehicles, placingincreasing strain on logistics and safety resilience (ICE, 2025).
Substandard bridges often have imposed weight restrictions, ranging from partial load limits to complete closure for certain vehicle types. These restrictions are primarily due to identified structural deficiencies such as:
Material degradation: corrosion of steel reinforcement, concrete spalling, freeze-thaw damage.
Fatigue and stress accumulation: due to traffic volume and increasing vehicle weights over time.
Design limitations: older bridges designed to standards not reflecting modern loading requirements.
Repair aspirations vs. Realistic outcomes
Local authorities now identify around 2,928 substandard bridges in Great Britain (≈ 4% of council-maintained bridges), of which they hope to fully restore nearly 2,000, yet only 292 are projected to receive full repair work over the next five years due to budget constraints (RAC Foundation & ADEPT, 2024). This shortfall means that over 80% of the identified bridges will remain under-capacity or carry weight restrictions, impacting the efficiency of our transport system.
The gap between the desired and feasible repair schedules highlights systemic funding challenges and the need for prioritisation frameworks.
Financial backlog and investment requirements
The cost to bring all substandard bridges up to current safety and capacity standards is estimated at £1.16 billion. When considering the full maintenance backlog across all council-managed bridges -which includes routine inspections, preventive maintenance, rehabilitation, and replacement - the figure rises dramatically to approximately £5.44 billion (RAC Foundation, 2019).
This backlog reflects:
- Deferred maintenance accumulating over years of underinvestment
- The increasing cost of materials and specialised labour
- Complexities related to upgrading bridges while minimising traffic disruption
Regional distribution and hotspots
Some regions exhibit higher concentrations of substandard bridges:
Devon: 224 substandard bridges
Cheshire East: 194 substandard bridges
Essex: 151 substandard bridges
Of particular note is Slough, where 47% of the 36 bridges are substandard, indicating an acute localised infrastructure risk (RAC Foundation, 2019).
Bridge collapses and safety incidents
Alarmingly, there has been a 70% increase in local road bridge collapses over a recent 12-month period, rising from 10 to 17 incidents (Highways Magazine, 2022). While overall rare, each collapse underscores the potential catastrophic consequences of deferred maintenance and ageing infrastructure, including loss of life, economic disruption, and increased emergency repair costs.
Understanding the impact
The implications of these findings go beyond statistics. Substandard bridges affect freight movement efficiency, local economies, and community connectivity. Weight restrictions often force detours that increase travel times, costs and carbon impact. Moreover, aging or poorly maintained bridges pose safety hazards, which could have severe consequences if left unaddressed. The Public Accounts Committee (2025) recently described the deteriorating state of local roads and infrastructure as a “national embarrassment,” highlighting the urgency for coordinated national intervention to address the estimated £15 billion repair backlog.
Budgetary constraints continue to be the major barrier for councils. The substantial backlog and limited resources result in prioritising reactive maintenance over proactive upgrades. This reactive approach may save costs in the short term but could lead to exponentially higher expenses if bridges fail or require emergency repairs.
How Sika can help
The repair and maintenance backlog facing local authorities and national bodies is daunting. In a troubled national economy, they are increasingly being asked to do more with less and prioritise spending to prevent worst-case scenarios. Material manufacturers like Sika can work with engineers and contractors to ensure that bridge refurbishment works achieve the desired results and fully consider the causes of deterioration, exposure conditions and the required design life. Optimised specification and delivery can ensure return on investment and offer piece of mind to owners who can focus on the next project, knowing that high quality materials and systems are extending the life of their refurbished asset.
Looking ahead: What needs to change?
Increased Investment
The £5.44 billion maintenance backlog cannot be ignored if Britain’s road bridges are to remain safe and reliable.
Innovative Technologies
Embracing new materials and digital monitoring systems can prolong bridge lifespans and provide early warning signs of deterioration.
Strategic Prioritisation
Councils must adopt a risk-based approach, focusing resources on the most critical structures first.
Policy and Funding Support
National and regional governments must prioritise infrastructure funding and provide clear frameworks that enable sustainable bridge management.
Conclusion
Britain’s bridge network is at a critical crossroads. With nearly 3,000 structures unable to carry modern traffic loads and a repair backlog exceeding £5 billion, the evidence points to a system under strain from years of underinvestment. While local authorities continue to manage risk through inspections and weight restrictions, the growing number of substandard bridges and recent rise in structural failures underline the urgent need for a coordinated, long-term response.
Addressing this challenge will require more than short-term fixes. Sustained investment, risk-based prioritisation, and the adoption of modern materials and monitoring technologies can help extend asset life and reduce whole-life costs. Collaboration between public authorities, engineers, and material specialists will be key to achieving durable, value-driven repairs.
Ultimately, ensuring the safety, reliability, and resilience of Britain’s bridges demands a national commitment to proactive asset management - one that balances engineering excellence with financial realism to safeguard critical transport links for future generations.
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References
BBC News. (2014, December 18). Councils in England face huge road repair bills. BBC News.https://www.bbc.co.uk/news/uk-england-30684854
Highways Magazine. (2022, March 24). Local bridge standards decline and full collapses increase. Highways Magazine. https://www.highwaysmagazine.co.uk/Local-bridge-standards-decline-and-full-collapses-increase/9602
Institution of Civil Engineers. (2025, September). Why the UK needs to spend £50 bn to salvage its local road network. ICE Knowledge Hub. https://knowledgehub.ice.org.uk/news/summer-prestige-debate-2025-analysis/
Public Accounts Committee. (2025, January 17). Local roads branded “national embarrassment” as Govt urged to tackle £15bn repair backlog. UK Parliament Committees.
https://committees.parliament.uk/committee/127/public-accounts-committee/news/204755/local-roads-branded-national-embarrassment-as-govt-urged-to-tackle-15bn-repair-backlog/
RAC Foundation. (2019, January 7). Council bridge maintenance backlog grows. RAC Foundation. https://www.racfoundation.org/research/economy/council-bridge-maintenance-backlog-grows
RAC Foundation & ADEPT. (2024, March). Changing weather patterns worrying bridge engineers. RAC Foundation. https://www.racfoundation.org/media-centre/changing-weather-patterns-worrying-bridge-engineer