Poorly maintained bridges are a ticking time bomb that only radical action can defuse

Since the turn of the millennium, 66 fatal bridge collapses are known to have taken place worldwide.

Together, these catastrophic structural failures have claimed more than 1,200 lives.

The combination of ageing assets, shrinking maintenance budgets and ever more extreme weather is only increasing the likelihood of more incidents.

And, as the ICE’s latest State of the Nation report notes, this “perfect storm” applies as much in the UK as it does anywhere else.

To address it, innovative and coordinated maintenance is urgently needed.

A ‘ticking time bomb’

Much of the UK’s trunk road network (highways managed at the national level) was built 50-plus years ago to designs that didn’t anticipate today’s traffic loads and climate stresses.

The declining condition of this and other key transport infrastructure nationwide represents a “ticking time bomb”, according to Helen Rowe, structures asset manager at Kent County Council.

She shared this stark assessment with fellow senior engineers at a recent roundtable hosted by the ICE and Hilti, a provider of construction technology and services.

Rowe also chairs the national bridges group at the Association of Directors of Environment, Economy, Planning and Transport (ADEPT).

A 2023 report by the association, whose members include senior highways officers at UK local authorities, estimated that ending the maintenance backlog on road bridges alone would cost nearly £5.9bn.

It also noted 3,000 bridges around the country couldn’t safely carry the heaviest road-legal vehicles.

In June 2025, the government did at least earmark £1bn for repairs to “broken bridges, ruined roads and tired tunnels”.

To make this fund go as far as possible, highways authorities will need to adopt some innovative measures – and fast.

Advanced digital technologies

Assessing the condition of ageing structures and coming up with ways to keep them in service requires different skills from those needed for designing new assets.

Budget cuts in recent years have meant that highways authorities are lacking engineers well versed in commissioning, supervising and conducting bridge inspections.

To help make up for this shortage, they are starting to use emerging tech such as AI to analyse inspection data and better predict structural decline patterns.

Despite such advances, some experts are cautious about becoming too reliant on the technology. They include Mark Reed, regional structures lead for southern England and Wales at Amey.

“AI and machine learning are good tools,” he told the roundtable. “But, if we’re not careful, we may erode engineers’ ability for critical thinking, which would lead to a different problem in 10 or 15 years.”

A whole-system overview

A highway network is a system that behaves in complex ways, especially when key elements are disrupted.

Having just one bridge out of service, for instance, could affect several routes other than the road it carries. The closure would divert heavier traffic onto them and, in turn, put more stress on their structures.

As such, it’s crucial to take account of this broader context when overhauling individual assets.

Some speakers at the roundtable suggested that it would be valuable to establish a national database of bridges, enabling owners to share information about their condition.

This would lead to a more holistic approach under which funds could be allocated to repairs that would most benefit the entire network.

Novel methods and materials

If the bridge maintenance backlog is to be reduced as cost-efficiently as possible, new repair techniques may be worth trying.

Innovations could include the use of advanced composite materials and ultra-high-performance concrete.

Meanwhile, prefabricated modular systems could be used on structures needing urgent reinforcement.

Rickard Bergeryd, Hilti’s regional codes and approvals manager, structural connections, said: “Specialist suppliers are investing heavily in researching and developing solutions to asset maintenance challenges.

“These challenges can be complex, but a lot of asset owners experience similar issues so there is potential for sharing knowledge and moving innovative techniques more quickly from trial stage to widespread adoption.

“Many of the solutions being developed build on existing technologies, such as the use of post-installed threaded rods as shear reinforcement, and the innovation comes from using them in a different way.”

The infrastructure sector can understandably be wary of applying novel materials and techniques to safety-critical assets, but the situation demands that they at least consider such options.

Evidence gathering would be key

Inevitably, any decision to try a new approach will hinge on who is willing to accept responsibility should it not work as planned.

Consultants can be reluctant to deliver bespoke designs, while asset owners want evidence that new solutions have been tested thoroughly and that they pose an acceptable level of risk.

One option could be to establish an independent expert panel to assess use cases for non-traditional methods.

Its members would weigh up the risks and potential benefits of a given solution and identify where further testing or external approval might be needed.

This could work at an individual project level, but it would be more beneficial if it were an industry-wide arrangement.

That would enable any authority considering a novel technique to see evidence that’s already been gathered on it and so quickly determine whether that approach would be beneficial.

The main message to take away from the roundtable is that such measures are urgently needed if the UK's critical transport infrastructure is to be kept safe.