Council bridge maintenance backlog grows07 Jan 2019

Bill has hit £6.7 billion

The one-off cost of clearing the total maintenance backlog for the near 72,000 council-managed road bridges in Great Britain has increased by a third.

Analysis by the RAC Foundation of data for the 2017-18 financial year shows that an estimated £6.7 billion is needed to carry out all the work that would be required on the tens of thousands of local authority bridges (defined as structures over 1.5m in span).

This is up from £5 billion a year earlier (2016-17).

The study is based on data provided by 200 (out of a total of 207) councils across England, Scotland and Wales.

Between them the 200 councils manage 71,652 bridges, of which 3,177 (4.4% of the total) are categorised as ‘substandard’.

Substandard means unable to carry the heaviest vehicles now seen on our roads, including lorries of up to 44 tonnes.

Many of the substandard bridges are subject to weight restrictions. Others will be under programmes of increased monitoring or even managed decline.

The proportion (4.4%) of substandard bridges is in line with that reported in 2016-17 (4.6% – 3,441 out of 74,005 bridges – based on data from 204 local authorities).

Between them, councils say they would ideally want to bring 2,026 (64%) of the 3,177 substandard bridges back up to full carrying capacity.

However, budget restrictions mean they anticipate that only 343 of these will have the necessary work carried out on them within the next five years.

The survey of local highways authorities was carried out by the RAC Foundation with the help of the National Bridges Group of ADEPT (the Association of Directors of Environment, Economics, Planning and Transportation).

The ten councils in Britain with the highest number of substandard bridges are:

Local Authority Number of bridges* Number of substandard bridges Proportion of substandard bridges
Devon     2,712 244 9%
Essex       910 167 18%
Somerset     1,483 160 11%
Cornwall     1,007 140 14%
Suffolk        924 140 15%
Northumberland        972 80 8%
Lancashire     1,469 77 5%
Cumbria     1,911 71 4%
Gloucestershire        962 66 7%
Aberdeenshire     1,293 65 5%


The ten councils in Britain with the highest proportion of substandard bridges are:

Local Authority Number of bridges Number of substandard bridges Proportion of substandard bridges
Lewisham 34 18 53%
Hammersmith and Fulham 4 2 50%
Bristol 140 52 37%
Islington 7 2 29%
Southend-on-Sea 83 22 27%
Kensington and Chelsea 4 1 25%
Barking and Dagenham 13 3 23%
Bexley 82 18 22%
Conwy 291 63 22%
Sutton 19 4 21%


Despite the financial pressures, annual expenditure by councils on maintaining bridges rose from an estimated £367 million in 2016-17 to £598 million in 2017-18.

Whilst no local authority manages structures directly technically comparable with the bridge that collapsed in Genoa in August 2018, they do have are a number of so-called post-tensioned (PT) bridges with hidden cables.

These PT bridges require intrusive inspections (Post-Tensioned Special Inspections or PTSIs) that can cost £100,000.

The number of PT bridges that are local-authority managed and how many require inspections:

Local Authorities that have PT bridges Total number of PT bridges Bridges that have had PTSIs in the last 18 years Bridges that require but have not had PTSIs in last 18 years Estimate of funding required for the additional PTSIs
106 605 305 199 £21.4 m

(based on the £15.5 million needed for 144 bridges that we have data for.)


The RAC Foundation also asked national roads authorities how their bridges were faring:

Number of bridges Number of substandard bridges Proportion of substandard bridges
Highways England 11,067 83 1%
Transport Scotland 2,641 38 1%
Welsh Assembly 1,251 96 8%