Drivers in and around the Forest of Dean will have 10 National Highways road closures to watch out for this week.

And one of them is expected to cause severe delays – with motorists facing a holdup of at least 30 minutes. Another three will cause moderate delays of between 10 minutes and half an hour.

The latest expected works list, with notes from National Highways, shows that two closures already in place are expected to carry on this week:

• M4, from 8pm May 12 to 6am May 13, moderate delays (10-30 minutes): M48 westbound, junction 2 to junction 23 M4 carriageway closure for South Wales Trunk Road Agent, diversion via M48/M4 eastbound, turn at, junction 20 and return westbound, M4 via Prince of Wales bridge.

• A38, from 8pm January 8 to 6am July 31, severe delays (more than 30 minutes): M5 northbound and southbound, junction 7 to junction 11, M50 eastbound, and westbound, junction 2 to M5, carriageway, slip road, lane closures, with 24/7 narrow lanes, lane closure, and 50mph speed limit due to improvement works, diversion via National Highways and local authority network.

And a further eight closures will begin over the next two weeks:

• M4, from 9pm May 13 to 6am May 14, slight delays (under 10 minutes): M4 westbound, junction 22, lane closure to South Wales Trunk Road Agent.

• M5, from 10pm May 15 to 5am May 17, slight delays (under 10 minutes): M5 Both directions, junction 11A to junction 12, lane closures for barrier repairs.

• M4, from 9pm May 16 to 6am May 17, slight delays (under 10 minutes): M4 eastbound, junction 23 to 22 Prince of Wales Bridge - lane closures for structure maintenance.

• M50, from 9pm May 17 to 6am May 18, slight delays (under 10 minutes): M50 westbound, junction 2 to junction 3, Lane closure for maintenance works.

• M4, from 10pm May 17 to 8pm May 19, moderate delays (10-30 minutes): M48 eastbound, junction 2 to junction 1 Severn Bridge carriageway closure for structure maintenance, diversion via M4 Prince of Wales Bridge, diversion for, junction 1 via M4, junction 19, M32, junction 1 and return.

• M48, from 10pm May 17 to 8pm May 19, slight delays (under 10 minutes): M48 westbound, junction 1 to 2 Severn Bridge lane closure for structure maintenance works.

• A449, from 9pm May 18 to 6am May 19, moderate delays (10-30 minutes): M50 eastbound, junction 4 to junction 2, carriageway closure for maintenance works, diversion via National Highways and local authority network.

• M4, from 9pm May 22 to 6am May 24, slight delays (under 10 minutes): M4 eastbound, junction 23 to 22 Prince of Wales Bridge - lane closures for structure maintenance.

National Highways is responsible for maintaining motorways and major A-roads, so closures of smaller roads will not be included in their schedule.