Picture caption: The Millau Viaduct, Southern France – Picture credit: Jordi Vich Navarro on Unsplash
When a bridge collapses in Italy, what do you do? Well, if you’re France, you learn from this tragedy, and you undertake a project to survey 45,000 bridges in just 18 months.
After part of the Ponte Morandi in Genoa collapsed in 2018, killing 43 people and injuring 16 as vehicles fell into the Polcevera river below, countries across the continent were forced to take a good look at their infrastructure. No one wanted to see a repeat of this disaster. Yet it was unclear what, if anything, was being done to prevent something similar happening elsewhere in Europe.
In France, officials realised they had no national inspection programme in place for local bridges, meaning it was impossible for them to have a clear picture. And the situation was complicated by the fact that there are 36,000 road authorities across France, responsible for an estimated 100,000 bridges.
The French public agency, Cerema (the Centre for Studies and Expertise on Risks, the Environment, Mobility and Urban Planning), was tasked with leading a survey. They had six months of preparation time, followed by 18 months to carry out the census of key bridges. Two hundred and fifty agents worked on the project, with each bridge survey including approximately 150 questions plus a 12-page “health diary”.
This created an incredible amount of data, but with each agent using Esri’s ArcGIS Survey123, a mobile GIS app for phones or tablets, it was easy for staff at Cerema to track the inspection progress.
Ultimately, they were able to create an interactive online map of every bridge surveyed, which was made available to the public. The data showed that 10% of the bridges and retaining walls surveyed needed immediate attention and 21% required significant repairs. That’s a lot of bridges!
The survey was completed in 2023. Initially, 11,500 municipalities took part, but more have agreed to participate now they’ve seen the results of the survey.
A national approach like this makes sense. It’s something we should perhaps consider in the UK, as cash-strapped local authorities are surely finding it more challenging to stay on top of surveys and ongoing maintenance. No doubt finding competent people with a head for heights is a challenge too – this work wouldn’t be my idea of fun.
Earlier this year, the RAC Foundation discovered that one in every 25 council-maintained road bridges in the UK has been found to be substandard. This refers to a bridge which is not able to support the weight of a 44-tonne lorry, the heaviest allowed on UK roads. By using Freedom of Information (FOI) requests, the RAC Foundation has revealed that 2,928 bridges across England, Scotland and Wales are considered substandard.
And back in 2020, an FOI request by The Times revealed that nearly half of the bridges on our motorways and A-roads had sections which were in “poor” or “very poor” condition.
On the plus side, it’s clear that we are surveying our bridges. And it’s important to note that Highways England’s Chief Highways Engineer, Mike Wilson, has said, “All our structures are safe and regularly inspected. A rating of “poor” or “very poor” does not mean that a structure is unsafe; it is simply a way of recording a visual inspection, such as the condition of the paint, to allow us to consider the future maintenance requirements.”
That’s somewhat reassuring, but with vehicles getting heavier, let’s hope that any critical repairs are being carried out promptly. The average weight of a new car has increased by nearly 400kg since 2016, according to Autocar data, from 1553kg to 1947kg. That’s a lot of extra weight on our bridges.
Perhaps we don’t need to undertake a project on the scale of the French bridge survey, but it would be good to have a publicly available map of the UK, with recent survey data for each bridge. This would be a more sensible approach, rather than tightly guarded information only being made available at the request of the UK’s press and motoring organisations.
Meanwhile, if you need assistance with the structural elements of an upcoming project, please do get in touch.
