Drivers in and around the Forest of Dean will have 12 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 two will cause moderate delays of between 10 minutes and half an hour.

• A40, 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, to 6pm August 22, slight delays: M50 both directions M5, junction 8 to A449 Travellers rest roundabout, Lane closures for maintenance works.

• A40, from 8am August 19 to 4.45pm August 21, slight delays (under 10 minutes): A40 Dursley Cross traffic lights for Gigaclear works.

• A40, from 8am August 20 to 4.45pm August 22, slight delays (under 10 minutes): A40 Huntley to Birdwood traffic lights in place for Gigaclear 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.

• A38, from 9.30pm August 20 to 6am August 21, moderate delays (10-30 minutes): M50 both directions, junction 1, entry and exit slip road closure for maintenance works, diversion via National Highways network.

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

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

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

• M48, from 10pm September 2 to 6am September 3, slight delays: 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.