The Uxbridge Road (A4020) is an east-west road that connect Uxbridge in the west to Shepherd's Bush in the east. It changes its names several times along its length (The Vale, Ealing Broadway, Hanwell Broadway, etc) and hosts several shopping districts (Shepherds Bush High Street, Acton High Street, Ealing Broadway, West Ealing Broadway, Hanwell Broadway), Ealing hospital and many residential areas.
It is also considered by some to extend further into town - the one-way system at Shepherd's Bush, as well as the Shepherd's Bush roundabout being the only blips in the chain. East of Shepherd's Bush it becomes Holland Park Avenue, then Notting Hill Gate, Bayswater Road, Marble Arch, Oxford Street, New Oxford Street, Bloomsbury Way, Theobald's Road, Clerkenwell Road, [Old Street]? and Hackney Road - at which point it peters out.
For motorists, it varies quite a lot depending on where you are, but is a major route through west london (although a lot of its traffic now uses the A40 and A4). Everthing east of Shepherd's Bush is a motorist's nightmare for most of the day, but to the west, the main sticking points are in the middle of Acton town centre, Ealing Common (the junction with the North Circular), Ealing Broadway, West Ealing Broadway (at the junction with Northfields Avenue/Argyll Road), [Hanwell]? Broadway and [Southall]?. After [Hanwell]? Broadway it opens up into a multi-laned major-ish road, until you reach [Southall]?. [Southall]? is a major sticking point, especially at weekends, when the Asian communities do the bulk of their trading. Beyond [Southall]? is dual carriageway, leading through Hayes and Hillingdon, to Uxbridge.
Bus Route 207 and limited stop version 607 run the length of Uxbridge Road, from Shepherd's Bush Green to Uxbridge Bus Station (not all run all the way to Uxbridge, though).