The A390 is a road in Cornwall

Cornwall

Cornwall is a unitary authority and ceremonial county of England, within the United Kingdom. It is bordered to the north and west by the Celtic Sea, to the south by the English Channel, and to the east by the county of Devon, over the River Tamar. Cornwall has a population of , and covers an area of...

 and Devon

Devon

Devon is a large county in southwestern England. The county is sometimes referred to as Devonshire, although the term is rarely used inside the county itself as the county has never been officially "shired", it often indicates a traditional or historical context.The county shares borders with...

, England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

. It runs from Tavistock to 5 miles (8 km) north west of the city of Truro

Truro

Truro is a city and civil parish in Cornwall, England, United Kingdom. The city is the centre for administration, leisure and retail in Cornwall, with a population recorded in the 2001 census of 17,431. Truro urban statistical area, which includes parts of surrounding parishes, has a 2001 census...

. Starting in Tavistock, it heads south-westwards towards Liskeard

Liskeard

Liskeard is an ancient stannary and market town and civil parish in south east Cornwall, England, United Kingdom.Liskeard is situated approximately 20 miles west of Plymouth, west of the River Tamar and the border with Devon, and 12 miles east of Bodmin...

, crossing over the River Tamar

River Tamar

The Tamar is a river in South West England, that forms most of the border between Devon and Cornwall . It is one of several British rivers whose ancient name is assumed to be derived from a prehistoric river word apparently meaning "dark flowing" and which it shares with the River Thames.The...

 and into Cornwall, then through Gunnislake

Gunnislake

Gunnislake is a large village in east Cornwall, United Kingdom. It is situated in the Tamar Valley approximately ten miles north of Plymouth...

 and Callington. Immediately before Liskeard, it merges with the A38

A38 road

The A38, part of which is also known as the Devon Expressway, is a major A-class trunk road in England.The road runs from Bodmin in Cornwall to Mansfield in Nottinghamshire. It is long, making it one of the longest A-roads in England. It was formerly known as the Leeds — Exeter Trunk Road,...

 north of the town. It diverges from the A38 at Dobwalls

Dobwalls

Dobwalls is a village in south-east Cornwall, United Kingdom. It is situated three miles west of Liskeard.The name is spelt Dubwalls on Bartholomew's map and Black's Guide of 1879....

, where it then runs in a south-westerly direction to Truro

Truro

Truro is a city and civil parish in Cornwall, England, United Kingdom. The city is the centre for administration, leisure and retail in Cornwall, with a population recorded in the 2001 census of 17,431. Truro urban statistical area, which includes parts of surrounding parishes, has a 2001 census...

 via Lostwithiel

Lostwithiel

Lostwithiel is a civil parish and small town in Cornwall, England, United Kingdom at the head of the estuary of the River Fowey. According to the 2001 census it had a population of 2,739...

, St. Blazey, and St Austell

St Austell

St Austell is a civil parish and a major town in Cornwall, England, United Kingdom. It is situated on the south coast approximately ten miles south of Bodmin and 30 miles west of the border with Devon at Saltash...

. It then forms a loop, and bypasses Truro City Centre. It then heads north west out of the city, where it forms the main corridor into Truro from the west. It passes the Royal Cornwall Hospital and through the suburb of Threemilestone

Threemilestone

Threemilestone is a small village in the civil parish of Kenwyn, located precisely three miles west of Truro, the only city in Cornwall. Threemilestone has grown in recent years, with newly developed housing estates to the west...

, before linking up with the A30 road

A30 road

The 284 miles A30 road from London to Land's End, historically known as the Great South West Road used to provide the most direct route from London to the south west; more recently the M3 motorway and A303 road performs this function for much of the route and only parts of A30 now retain trunk...

 at Chiverton Cross

Chiverton Cross

Chiverton Cross is a road junction in Cornwall, United Kingdom, about four miles north-east of Redruth and five miles west of Truro at OS grid reference ....

, where the A390 terminates. It forms part of the main route (the Truro to Dobwalls section) from Truro to Plymouth

Plymouth

Plymouth is a city and unitary authority area on the coast of Devon, England, about south-west of London. It is built between the mouths of the rivers Plym to the east and Tamar to the west, where they join Plymouth Sound...

, although after a severe accident in Lostwithiel in 1999 heavy goods vehicles are diverted from it at the top of Edgcumbe Road, Lostwithiel

Lostwithiel

Lostwithiel is a civil parish and small town in Cornwall, England, United Kingdom at the head of the estuary of the River Fowey. According to the 2001 census it had a population of 2,739...

.

By far the busiest section of the road is between Truro City Centre and Chiverton Cross, where it carries through traffic to West Cornwall,as well as commuting traffic to and from Truro, and traffic for the Royal Cornwall Hospital, Truro College

Truro College

Truro College is a tertiary institution located in Truro, Cornwall, in the United Kingdom. Following an exchange of governing bodies, Truro College merged with Penwith College in April 2008—the combined institution is known as Truro and Penwith College, though the sites retain their original names...

 and the Richard Lander School

Richard Lander School

The Richard Lander School is a secondary school, a specialist technical college, in Truro, Cornwall, in the United Kingdom. It is named after Richard Lemon Lander...

. There are many residential new housing estates in this area which have created further traffic. The section from Truro College heading into Truro from the west also includes a bus lane

Bus lane

A bus lane or bus only lane is a lane restricted to buses, and generally used to speed up public transport that would be otherwise held up by traffic congestion...

 and some dual carriageway

Dual carriageway

A dual carriageway is a class of highway with two carriageways for traffic travelling in opposite directions separated by a central reservation...

sections.