The M275 is a short spur into Portsmouth, serving the city centre and ferry ports, that marks the end of its parent motorway, the M27.
The existence of this, the M275, and the M271 further west, suggests that once upon a time there were plans for at least three more spurs from the M27, and indeed there's some evidence to suggest that if everything had gone to plan we'd also have an M272, M273 and M274.
Its missing brethren aside, the M275 is probably the most impressive member of the very small group of motorways with three-digit numbers. It has an astonishing amount of public art along its length: The Sail of the South and the Tipner Masts (funded through Millennium Project money) are designed to be seen from the motorway.
The road itself is impressive too, being a major feat of engineering in its own right. It is built on land that was reclaimed from the sea, running across what was once a section of Portsmouth Harbour, drained and elevated to carry the motorway. Much of the material used for the man-made causeway is chalk, which came from the M27's deep cutting through Portsdown Hill between junctions 11 and 12.
Halfway along the M275 is Tipner junction, signposted for the park and ride site. It was part-built back in the 1970s when the M275 was first built, but was incomplete and unused for decades until it was finally completed and opened to traffic in 2014. Its proximity to other junctions caused Portsmouth City Council to lower the speed limit on the whole motorway to 60mph in preparation for its opening.
At its southern terminus, a hastily-built new access direct from the ferry port onto the northbound entry sliproad is a disappointing addition to an otherwise high-standard motorway. It introduces a traffic light junction under motorway restrictions, and it's missing signs that inform drivers they're entering a motorway at all. Pathetic Motorways explores the whole motorway, and that messy junction in particular.
One silly junction aside, though, the M275 packs an awful lot of impressive stuff into its two mile run.