Question to the Department for Transport:

To ask His Majesty's Government whether the National Highways statement that the eight bridges that carry the M6 and A685 over the Lune Gorge in Cumbria are “rapidly reaching the end of their serviceable life” after more than 50 years of operation applies to (1) all bridges on UK motorways and trunk roads of a similar age, (2) only certain bridges, and if so which others, or (3) only the eight bridges in Cumbria, and if so, why have these bridges in particular reached the end of their serviceable life in this time period.

The eight bridges that carry the M6 and A685 over the Lune Gorge in Cumbria are not representative of all motorway and trunk road bridges of a similar age. The issue with these structures relates specifically to half-joint details which are more vulnerable to deterioration.

National Highways is responsible for 378 half-joint structures, the majority of which are over 50 years old and require bespoke management strategies in line with the Design Manual for Roads and Bridges. However, not all the 378 half joint structures will have the same level of deterioration as Lune Gorge and need the same level of renewal.

Around half of all National Highways’ bridges (4574 bridges) are 50 years old or over, however the condition of bridge structures is influenced by many factors. Whilst the age of the structure can be a one of them, other factors such as structural form, quality of construction, different materials, environmental exposure and traffic loading are often of greater significance in the deterioration of a structure. It is more likely that older assets will require significant renewals interventions, but not all of these could be described as rapidly reaching the end of their serviceable life and in need of replacement.