The Forest of Dean's motorists will have 11 road closures to avoid nearby on the National Highways network this week.

And one of them is expected to cause major delays – with drivers facing a wait of at least 30 minutes. Another five 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:

• A40, from 8pm July 11 to 6am July 16, moderate delays (10-30 minutes): A40 Huntley multiway traffic lights in place for Gigaclear works.

• A38, from 8pm January 8 to 6am August 3, 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 nine closures will begin over the next two weeks:

• M4, from 8pm July 15 to 6am July 17, moderate delays (10-30 minutes): M4 westbound, junction 21 to 23 closed for carriageway renewals, diversion via M48 westbound. M49 northbound, traffic via M4 east to M5, junction 16, u-turn, M5 northbound to junction 15 and M4 westbound.

• A40, from 7pm July 17 to 7am July 30, slight delays (under 10 minutes): A40 Over to Lea used as a diversion route for Gloucestershire County Council closure of the A449 Preston Cross.

• A40, from 8pm July 17 to 6am July 19, slight delays (under 10 minutes): A40 Birdwood traffic lights in place for Severn Trent Water works.

• M5, from 8pm July 17 to 6am July 18, slight delays (under 10 minutes): M5 both directions, junction 12, lane closures for barrier works.

• M4, from 10pm July 17 to 6am July 19, moderate delays (10-30 minutes): M4 eastbound, junction 23 to 22 Prince of Wales Bridge closed for carriageway renewals, diversion via M48 eastbound to M4, junction 21.

• M4, from 8pm July 20 to 6am July 21, moderate delays (10-30 minutes): M4 westbound, junction 21 to 23 closed for carriageway renewals, diversion via M48 westbound. M49 northbound, traffic via M4 east to M5, junction 16, u-turn, M5 northbound to junction 15 and M4 westbound.

• A40, from 7pm July 22 to 6am July 25, slight delays (under 10 minutes): A40 Huntley, traffic lights installed by Gigaclear.

• M5, from 9pm July 23 to 6am July 24, slight delays (under 10 minutes): M5 northbound, junction 12, lane closure for electrical works.

• M4, from 8pm July 27 to 6am July 28, moderate delays (10-30 minutes): M4 westbound, junction 21 to 23 closed for carriageway renewals, diversion via M48 westbound. M49 northbound, traffic via M4 east to M5, junction 16, u-turn, M5 northbound to junction 15 and M4 westbound.

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