Travellers on the busiest routes between Wales and England could face disruption in July as both the M4 Severn Bridge and Severn rail tunnel will close for repairs.

Trains between south Wales and Bristol, London and England’s south coast will be affected by the Severn Tunnel’s 16-day closure between Wednesday 3 July and Friday 19 July.

The M4 bridge will also close eastbound on Wednesday and Thursday 10 and 11 July – although the original M48 Severn Bridge is due to remain open when its sister crossing is closed.

Highways England, which maintains the two Severn bridges, warned commuters and tourists they will face delays until autumn as there will be a two-lane contraflow on the bridge so workers can do resurfacing work.

It means on occasions in July, the only main route between south Wales and the south west of England will be over the M48 bridge linking Chepstow and Aust.

Highways England said it would also need more overnight closures of the M4 bridge later in summer and autumn as road resurfacing progresses.

“If using the bridge this summer, please expect delays and be prepared to use the M48 to help ease congestion,” said the road agency.

“Doing this work in the summer reduces the risk of the M48 bridge being closed due to weather, providing an alternative route for anyone crossing the river.”

It comes as train passengers between south wales and England face more than two weeks of disruption with the Severn Tunnel closure between Wednesday 3 July and Tuesday 9 July.

It means travellers on mainline trains between south Wales and London face at least an hour extra on their journey as the service will go via Gloucester and not stop in Bristol.

Network Rail has also warned there will be a limited rail replacement service running between Newport, Severn Tunnel Junction and Bristol Parkway – with none running direct to Bristol Temple Meads.

Engineers will replace four miles (7km) of track – the entire length of the south Wales-bound side – by installing 66 new rails.

The team will also install 10,800 sleepers and more than 22,000 tonnes of new ballast and remove 21,000 tonnes of spoil.

Workers will also replace some 900m (2,950ft) of track at Cattybrook near Almondsbury and more than 230m (750ft) of track drainage will be replaced at Patchway Gap – between the two Patchway tunnels near Bristol.

The Severn Tunnel will also be closed for follow-up work on the weekends of 27 and 28 July and 24 and 25 August.

Music fans attending big outdoor concerts in south Wales this July could be affected getting to and from those shows and have been warned to plan ahead and leave additional time for their journeys.

Shania Twain, Sir Tom Jones and Hozier are booked at Chepstow Racecourse on 5 July and 6 July respectively while the Severn Tunnel is shut.

The National, Manic Street Preachers, Suede, JLS, Idles, Noel Gallagher and Madness are also set to play Cardiff Castle when the tunnel is closed.

Fans going to watch Rick Astley and Lightning Seeds at Cardiff Castle on 10 July are warned that the Severn Tunnel and the M4 Prince of Wales bridge eastbound towards Bristol will be shut after the show.