M48 Breakdown
Recovery Service

The M48 carries traffic across the original Severn Bridge, one of the most iconic structures in British civil engineering. When it opened in 1966, the bridge was the longest suspension bridge in the UK and transformed travel between England and South Wales by eliminating the old car ferry between Aust and Beachley. The bridge's elegant design, with its aerodynamically shaped deck suspended by cables from two towers rising 445 feet above the estuary, remains a striking sight. But for drivers, especially those in high-sided vehicles, crossing the Severn Bridge can be a white-knuckle experience when the wind picks up.

The M48 is just 5 miles long, running from the M4 at Aust in South Gloucestershire across the bridge and its approach viaducts to Chepstow in Monmouthshire. The Aust end connects with the M4 at Junction 21, and the Chepstow end feeds into the A466, which runs through the spectacular Wye Valley towards Monmouth. Since the opening of the Second Severn Crossing (now the Prince of Wales Bridge on the M4) in 1996, the M48 and its bridge have carried significantly less traffic, but the old crossing remains an essential alternative route whenever the newer bridge is closed.

High winds are the defining hazard of the M48. The Severn Estuary funnels Atlantic weather systems into a wind corridor that strikes the bridge broadside. Wind restrictions are implemented in stages: at certain speeds, the bridge is closed to high-sided vehicles, motorcycles, and caravans; at higher wind speeds, it closes to all traffic. These closures can happen with little warning, trapping vehicles on the approach roads. The bridge deck itself creates its own microclimate — even when conditions on land are calm, wind accelerating over and around the bridge structure can produce gusts strong enough to push vehicles sideways. The toll booths that once stood at the Aust end have been removed since tolls were abolished in December 2018, but the legacy of the toll infrastructure — narrow lanes and sudden speed changes — lingers in the road layout. Chepstow, at the Welsh end, is a small town whose road network was never designed for the traffic volumes that a bridge closure can produce, and diversions through the town create their own chaos.