The B490 is a short route in the Acton area of west London. The road was originally unclassified; however, its number is the first new Class II road in the 4 zone outside central London, suggesting that the road dates to the mid-1920s.
The road runs south from the A4020 Acton High Street mostly under the name of Acton Lane, although there are sections called Winchester Street (at the northern end) and Beaconsfield Road (near the southern end). There's a brief one-way loop at the northern end around Acton Town Hall. Shortly after we pass beneath the North London line we meet a light-controlled junction with the B491 to the left.
At the end of the stretch known as Beaconsfield Road we come to a mini-roundabout. Here, with Acton Green Common in front and the B409 to the left, the B490 turns right, flanking the western side of the park. Our route then passes beneath the District Line by Chiswick Park station before crossing over another branch of the District to reach its terminus at traffic lights on the A315 Chiswick High Road, Gunnersbury.