Drivers in and around Cornwall will have 20 National Highways road closures to watch out for this week.

And one of them is expected to cause moderate delays – with motorists facing a holdup of between 10 minutes and half an hour.

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

• A30, from 7pm April 26 to 6am April 29, slight delays (under 10 minutes): A30 eastbound, Scorrier to Boxheater (B3285) and westbound, Boxheater to Chiverton Cross weekend carriageway closures for improvement scheme, eastbound, diversion via Blackwater, B3277, A3075 and B3285, westbound, diversion via B3285 and A3075.

• A30, from 7pm January 21 to 6am May 3, slight delays (under 10 minutes): A30 westbound, Two Bridges exit and entry slip road closures for South West Water works. Picnic site and toilets will be closed, exit slip diversion via A30 westbound to Plusha, B3257 and minor road to Lewannick, entry slip diversion via minor roads to Plusha. Traffic wanting to travel eastbound, on the A30 will be diverted via Fivelanes.

• A30, from 7pm March 10 to 6am May 3, slight delays (under 10 minutes): A30 westbound, Lewannick exit slip road closure for South West Water works, diversion via A30 westbound to Plusha, B3257 and minor road to Lewannick.

• A38, from 7pm April 22 to 6am June 1, slight delays (under 10 minutes): A38 both directions Saltash Tunnel to Carkeel Roundabout carriageway closed for sign erection works. Diversion via the B3271.

• A30, from 4am September 23 2023 to 6am June 9 2024, slight delays (under 10 minutes): A30 both directions Carland Cross to Mitchell contraflow for Chiverton to Carland improvement scheme. Variable speed restrictions.

• A30, from midnight, September 1 2020 to 6am June 9 2024, slight delays (under 10 minutes): A30 Carland Cross to Chiverton Cross improvement scheme.

And a further 14 closures will begin over the next two weeks:

• A38, from 7pm April 29 to 6am April 30, slight delays (under 10 minutes): A38 Landrake to Tideford temporary traffic signals for signage works.

• A38, from 7pm April 29 to 6am April 30, slight delays (under 10 minutes): A38 eastbound, Latchbrook to Carkeel Roundabout lane closure for sign erection works.

• A30, from 8pm April 29 to 6am May 3, slight delays (under 10 minutes): A30 between Zelah and Carland Cross traffic signals for Chiverton to Carland improvement scheme.

• A30, from 8pm April 29 to 6am April 30, moderate delays (10-30 minutes): A30 westbound, Highgate to Mitchell carriageway closure for road markings, diversion via A39, A392, A3058 and A3076.

• A30, from 8pm April 29 to 4am April 30, slight delays (under 10 minutes): A30 eastbound, Carland Cross to Summercourt lane closure for safety barrier repairs.

• A30, from 9am to 4pm on May 1, slight delays (under 10 minutes): A30 both directions Longrock Bypass - lane closure for survey works.

• A30, from 7pm May 1 to 6am May 4, slight delays (under 10 minutes): A30 both directions Loggans Moor to Treswithian closed for general maintenance works. Diversion via minor road through Roseworthy and Connor Downs.

• A30, from 7pm May 6 to 6am May 10, slight delays (under 10 minutes): A30 both directions Scorrier to Boxheater (B3285) carriageway closures for improvement scheme, eastbound, diversion via Blackwater, B3277, A3075 and B3285, westbound, diversion via B3285, A3075, Blackwater and A3047 to Avers junction.

• A30, from 7am to 7pm on May 7, slight delays (under 10 minutes): A30 westbound, Fivelanes lane closure for BT works.

• A30, from 8pm May 7 to 6am May 10, slight delays (under 10 minutes): A30 both directions St Erth Roundabout to Loggans Moor Roundabout closed for general maintenance works. Diversion via B3301 through Hayle.

• A30, from 7pm May 9 to 6am May 10, slight delays (under 10 minutes): A30 eastbound, Indian Queens to Callywith lane closures for drainage.

• A30, from 7pm May 10 to 6am May 13, slight delays (under 10 minutes): A30 both directions Scorrier to Boxheater (B3285) weekend carriageway closure for improvement scheme, eastbound, diversion via Blackwater, A3075 and B3285, westbound, diversion via B3285, A3075, Blackwater and A3047 to Avers junction.

• A38, from 7am to 10am on May 12, slight delays (under 10 minutes): A38 Bodmin Parkway traffic signals for BT works.

• A30, from 7pm May 13 to 6am May 15, slight delays (under 10 minutes): A30 both directions Treswithian to Tolvaddon carriageway closures for maintenance works, diversion via A3047.

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