Castle Cornet bridge inspection under way

Concrete specialists from McFarland Consulting are using an under-bridge inspection unit from Ireland. They will report their findings to Guernsey Ports.

‘The bridge was built in the 1950s. It’s a reinforced concrete bridge and all reinforced concrete degrades over time. It’s come to the end of its life,’ said Jenny Giles, project civil engineer at Guernsey Ports.

‘Underneath there is a lot of concrete spalling off and the steel reinforcement is exposed.

‘For a few years now we have been monitoring this bridge to see what residual strength it has left. It’s not going to get better, it’s not going to heal itself over time. It’s just going to get worse.’

The bridge has a series of sensors mounted underneath which provide stress readings each time it is crossed. However, it has now deteriorated to such an extent that it requires a full inspection annually.

In 2021, the public was warned not to go under the bridge because of an increased risk of falling concrete. Some of the steel is now exposed. The States Trading Supervisory Board, which is responsible for the bridge, believes the cheapest and most effective solution is to replace all of the concrete, and is expected to submit proposals to the States next year.

‘While we’re waiting for the project to be approved, we’re carrying on monitoring it to check it’s still safe to use,’ said Mrs Giles.

‘The guys will be checking all of the sensors as well as going underneath and looking for any bits of concrete that are loose and knocking them off to check how much has come off.

‘They will also measure how much steel is left so that they can calculate its strength, and take any hazards and dangers out of the way.’

For some time, vehicle access has been restricted to small vehicles only and drivers have to ask for permission to use the bridge.

‘It’s too early to predict the final outcome, but we know that it’s not going to be any better and we know it because every year they come and check it over,’ said Mrs Giles.

‘It’s very sensitive as to what loads we can put across the bridge.

‘We want to make it safe to be used. And when it’s not safe, we need to know that.

‘We know it’s deteriorating and it’s just the rate of deterioration we need to keep an eye on.’

Public access is further restricted during the inspection and there are safety notices on site.

Essential access to Castle Cornet will be maintained.