Heavy goods vehicles exceeding 7.5 tonnes will be permitted to cross the M48 Severn Bridge again from autumn next year through the introduction of a traffic management system, National Highways has revealed.
The transport authority plans to install signal controls at junction slip roads to regulate HGV movements across the structure, ending restrictions imposed in May following the discovery of cable deterioration.
Under the proposed arrangement, lorries travelling westbound will exit at Junction 1 while eastbound traffic leaves at Junction 2, with signals managing their return to the carriageway.
The system aims to distribute heavy vehicles along the bridge’s span rather than allowing them to cluster together, addressing structural concerns that prompted the current weight limit.
Since May, lorries above the 7.5-tonne threshold have been redirected to the M4 Prince of Wales bridge, creating disruption for haulage operators and businesses relying on the crossing between England and Wales.
The traffic management approach will function automatically for most periods, releasing lorries at intervals to prevent concentrated loads on the structure while also minimising delays for both commercial and private vehicles.
The system can also halt HGV access entirely during major incidents in the vicinity.
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.”
National Highways stated that a weight restriction along the M48 could be lifted
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He acknowledged the disruption to businesses and hauliers but emphasised the urgency of finding a solution.
Roads and Buses Minister Simon Lightwood said: “I am pleased to see National Highways making progress to allow HGVs to return to the M48 Severn Bridge next year.”
Laboratory testing completed in December 2024 confirmed that the bridge’s main suspension cables have weakened and continue to deteriorate, prompting National Highways to implement load restrictions to prevent additional damage.
The structure, which was not engineered to accommodate contemporary traffic volumes or vehicle weights, has undergone multiple evaluations and interventions concerning its suspension cables due to corrosion from severe weather exposure.
The preferred option for the M48 westbound
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NATIONAL HIGHWAYS
Modern lorries have doubled in weight from 22 tonnes to 44 tonnes since the bridge’s construction, while traffic volumes have surged dramatically over six decades.
Welsh Cabinet Secretary for Transport Ken Skates said: “We welcome and support the news from National Highways. We will continue to engage with the team as measures to address a longer-term solution for the Severn Bridge weight limit are explored.”
Alan Feist explained: “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.”
The bridge typically handles approximately 32,000 vehicles daily, with around 3,270 exceeding the 7.5-tonne limit, meaning the current restrictions have forced roughly 10 per cent of traffic onto the alternative M4 crossing.
The preferred option for the M48 eastbound
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NATIONAL HIGHWAYS
Traffic flow has risen by 34 per cent since toll charges were abolished in 2018, compounding stress on the ageing infrastructure.
Mr Feist warned: “Continued use of the bridge by heavier vehicles could ultimately see it closed to all traffic. We are acting now to prevent this from happening.”
Emergency services, scheduled bus services, coaches, gritting vehicles and recovery trucks remain exempt from the restrictions.
Should the Prince of Wales Bridge close unexpectedly, heavy vehicles must follow designated diversions using the M5 and M50 motorways.
