Analysis: Damaged bridges pose a challenge to flood-stricken areas

Severe storms last year have added to a backlog in maintaining the UK’s ageing bridges, and more floods are likely to make the situation worse. Councils hit hardest by the floods in late 2019 and 2020 face a combined bill of half a billion pounds to fix bridges in need of repair, E&T has calculated from Freedom of Information (FOI) data acquired by the RAC Foundation.

After last year’s heavy floods, local authorities in the North of England - such as Doncaster, Rotherham, Barnsley, Bassetlaw and Kirklees – warned of ‘lasting effects’, and local leaders called for more additional funding from the national government.

2020 saw further floods: storms Ciara and then Dennis brought new challenges for councils in the North. In Boroughbridge, North Yorkshire, the river Ure reached record levels of 15.12m to break its banks in several places. Floods in Bradford, West Yorkshire, closed the M606 motorway in both directions.

Bridges over flooding rivers are struck by debris in the fast-flowing water. “These bridges are hit by tree trunks and boulders on occasions, explained Philip Gomm from the Royal Automobile Club Foundation for Motoring (RAC). “The foundations may get scoured away.”

The effect Storm Dennis had on a bridge in Powys County Council, Wales, is a good example. The storm severely damaged a main road bridge based in Crickhowell (see below).

In Herefordshire (see map) in the West Midlands, floods last spring caused the River Wye to reach its highest level in recorded history, and both landslides and high river levels damaged roads and bridges across the area.

Herefordshire Council owns seven sub-standard bridges and with expected upgrade costs running to £12.7m, only three of the seven are intended to be returned to full load capacity in the next five years, RAC data suggests.

Every year, RAC conducts an initiative to collect councils’ responses on substandard bridge statistics. In 2019, it received FOI responses from 154 local authorities. ‘Substandard’ are bridge structures unable to carry the heaviest vehicles on our roads, including lorries of up to 44 tonnes, RAC states.

By comparing some of the most flood-stricken councils with maintenance statistics on substandard bridges E&T was able to identify where funding is needed most urgently (see illustration). Doncaster, Rotherham, Barnsley, Bassetlaw and Kirklees together operate 28 substandard bridges, totalling nearly £100m in backlog costs – costs that RAC defines as required to bring the stock of bridges to a good, but not necessarily perfect condition.

How much councils can spend often depends on their annual budget available for structural maintenance, which, on average is slightly above £3m across English councils, according to revenue account data. Many of the councils hit hardest by floods in 2019 and 2020 plan to spend below the national average.

Official statistics on planned budgets reveal severe underfunding for structural highway and transport maintenance projects in flood-hit councils. Bradford, affected by Storm Dennis in February, counts a total of 468 bridges but only plans to spend £1.7m in structural maintenance costs, accounting for just 16 per cent of its total highways and transport budget.

Somerset, hit hard by widespread December floods in 2019 and counting 1,507 bridges, had the third highest number of substandard bridges (153). Yet, it plans to only spend 8.3 per cent – or £2.4m - on structural maintenance out of the total highway and transport service budget. It plans to upgrade only ten bridges in the next five years.

E&T finds that none of the ten bridges in Doncaster and Rotherham - both spending less than half of what other local authorities spend on structural maintenance - are expected to be repaired in the next five years.

Devon, home to the most substandard bridges in RAC’s dataset, saw the Jubilee Bridge in Modbury collapse in 2013 after 50mm of rain fell within 24 hours. December 2019 floods brought rainfall of up to 53mm across Devon. Budget for structural maintenance as a share of total highway and transport service costs account for only 4.6 per cent. Out of the 241 substandard bridges, only one is planned to be restored to sufficient conditions.

In February 2020, the UK government decided to intervene with emergency flood funds available under its Bellwin scheme for financial assistance. It provided some relief to councils including Nottinghamshire, Leicestershire, Derbyshire, Shropshire, Telford and Wrekin, Worcestershire and Herefordshire, where 2020 spring floods raged. Yet this emergency funding can’t fix the structural problems of the 900 substandard bridges in flood-ridden councils.

Climate change means floods may become more severe more often in the future. One study led by Andrew Stevens at the University of Southampton looked at 100-years-worth of flood data for the UK. Researchers found an increase in reported flood events during the 20th and 21st centuries, though with variation from decade to decade.

As floods pose more of a strain to ageing bridge structures, the government may need to review how much councils can afford to fix them up. “It’s another refresher as our climate is changing,” Gomm says. “It is bringing more damage to the bridges than they would have had to deal with on a regular basis 30 or 40 years ago”.