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

And one of them is expected to cause severe delays – with motorists facing a wait of at least 30 minutes. Another two 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:

• A38, from 8pm January 8 to 6am September 7, severe delays (more than 30 minutes): M5 northbound and southbound, junction 7 to junction 9, 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.

• A449, from 9pm August 21 to 6am September 7, slight delays (under 10 minutes): M50 eastbound, junction 4 to junction 1, Lane closure for maintenance works.

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

• A40, from 7pm August 28 to 6am August 30, slight delays (under 10 minutes): A40 Huntley traffic lights in place for Severn Trent Water works.

• A40, from 8pm August 30 to 6am September 1, slight delays (under 10 minutes): A40 Highnam to Churcham traffic lights in place for Severn Trent Water works.

• M4, from 9pm August 30 to 6am August 31, 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 20, M5, junction 16 and return.

• M50, from 9pm August 31 to 6am September 1, slight delays (under 10 minutes): M50 westbound, junction 2 to junction 1, Lane closure for maintenance works.

• A40, from 7pm September 2 to 6am September 10, moderate delays (10-30 minutes): A40 Huntley multiway traffic lights in place for Gigaclear works. Includes diversion onto the A40 Huntley to Birdwood, for closure of Grange Court Lane.

• M48, from 10pm September 2 to 6am September 3, slight delays (under 10 minutes): M48 westbound, junction 1 exit slip road closure for horticulture works, diversion via M48, exit, junction 2, turn to join M48 eastbound to junction 1.

• M48, from 10pm September 2 to 6am September 7, slight delays (under 10 minutes): M48 both directions mobile lane closure for drainage works.

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