Transport Insights

National Highways has blamed the wrong kind of traffic as it insists that the sixty-year-old Severn Bridge is safe, while bringing in some fairly drastic measures just to allow HGVs to use it.

Goods vehicles weighing over 7.5 tonnes are currently not allowed on the bridge – now redesignated the M48 – but are diverted onto the M4 Prince of Wales bridge.

The problem is the continued corrosion of the cables that hold up the bridge decks, first discovered in 2006, which led to vehicles above 7.5 tonnes being banned from the outside lane in order stop having two lanes of heavy vehicles stuck on the bridge if an incident occurred.

Follow-up monitoring, which I witnessed in late 2020, found the problem had got quite a lot worse, leading to an outright ban on HGVs.

National Highways has now announced its preferred solution (of two) for the medium term, while it explores longer-term options.

From next autumn HGVs will leave the M48 at Junctions 1 (westbound) and Junction 2 (eastbound) via the off-slip roads with re-entry controlled by signals on the on-slips.

For the vast majority of the time the system would operate ‘freely’ to release HGVs so they are spread out across the length of the bridge and not concentrated together, creating very little delay to HGV or car traffic. 

The system can also be used to keep HGVs off the bridge if there is a significant incident in the area.

Alan Feist, Programme Leader for National Highways, said:

Safety is our number one priority, and this weight restriction is about keeping the bridge safe for use now and for years to come.

Whilst the bridge remains safe, it was not designed and built for today’s levels or weight of traffic. Vehicles have got heavier, and traffic levels have increased significantly over the last 60 years, putting greater load on the cables.

We appreciate that this has been disruptive for businesses and hauliers, but we have been working at pace to reach this solution and are pleased to be on track to get HGVs back onto the M48 Severn Bridge next year.

While it is undoubtedly true that vehicles have got heavier, and traffic levels have increased significantly over the last 60 years, it is also true that an awful lot of those vehicles now use the Prince of Wales bridge.