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

And one of them is expected to cause severe delays – with drivers 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 four closures already in place are expected to carry on this week:

• A40, from 8pm August 8 to 6am August 13, slight delays (under 10 minutes): A40 Huntley to Birdwood traffic lights in place for Severn Trent Water works.

• A40, from 8pm August 6 to 6am August 21, moderate delays (10-30 minutes): M50 westbound, junction 1 to junction 4, carriageway closure and lane closures due to resurfacing works, diversion via National Highways and local authority networks.

• A38, from 9am July 22 to 6pm August 22, slight delays (under 10 minutes): M50 both directions M5, junction 8 to A449 Travellers rest roundabout, Lane closures for maintenance works.

• 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.

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

• M4, from midnight, to 5am on August 12, moderate delays (10-30 minutes): M4 westbound, junction 21 to 23 closed for urgent barrier works, diversion via M48 westbound. M49 northbound, traffic via M4 east to M5, junction 16, u-turn, M5 northbound to junction 15 and M4 westbound.

• M5, from 9pm August 12 to 6am August 13, slight delays (under 10 minutes): M5 northbound, junction 12, exit and entry slips closed for survey works, diversion for northbound, exit slip, M5 northbound to junction 11 and return, diversion for northbound, entry slip, M5 southbound to junction 13 and return.

• A40, from 9am to 3pm on August 14, slight delays (under 10 minutes): A40 both directions Longhope, two-way traffic lights for emergency horticultural works.

• M5, from 9pm August 20 to 6am August 21, slight delays (under 10 minutes): M5 southbound, junction 12 to 13, lane closure for technology works.

• 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.

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