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Route of the M25 and A282

Officially named the London Orbital, nicknamed the 'Road to Hell', and frequently derided as nothing more than a very big car park, this is London's outermost beltway, one of the world's biggest ring roads — the M25.

Despite all this, the M25 isn't even a full circle. The Dartford Crossing (comprising the Dartford Tunnels and the Queen Elizabeth II Bridge) over the Thames in the east and its approach roads are designated A282, because the first Tunnel was built in the 1960s as a local connection. A second tunnel was added, and because it was a dual carriageway, 1980s planners considered it eminently suitable for routing the M25 through. It remained A282 nonetheless, and has since been adorned with a bridge to double its capacity.

It's not just the biggest ring road in the world, it has other accolades. The clockwise off-slip at Reigate is the longest sliproad in the world outside the USA, for example. Or if that doesn't impress, consider the fact that this was the most expensive motorway Britain ever built, coming in at a total of £909m in eleven years, or roughly £7.5m per mile.

Since its opening in 1986, it hasn't exactly been cheap to maintain, with a cable stayed bridge to double up capacity at Dartford, countless widening schemes and now expensive things like Variable Speed Limits in desperate attempts to keep traffic moving.

The eternal question is: why is a simple ring road, a 360-degree bypass of a city, so badly congested? There appear to be three principal reasons. First, as a sweetener to locals along the route, junctions were dropped in all over the place. They allowed the road to be built, but allowed lots of local traffic onto what was intended as a long-distance route. It also means the road is now used by many commuters.

Second, it was meant to be the outermost of three or four ring roads for London (for which see the Ringways feature); not counting the inner ring road and South Circular, which are signed routes along city streets, it is currently the outermost of one and a half ring roads.

Thirdly, and partly for the reasons above, the demand for this road was so grossly underestimated that when it was finally completed in 1986, it was already out of date. Demand outstripped capacity within a few short years and ever since then it's been a long and expensive battle to make things move once more.


Start Dartford (A282)
Finish Thurrock (A282)
Passes Swanley, Sevenoaks, Reigate, Staines, Heathrow [air], Watford, St Albans
Length 118 miles
Connects to M1, M3, M4, M11, M20, M23, M26, M40, A1, A1(M), A12, A13, A41

With thanks to John Morgan, James Wharton, Paul Chu, Tony, Shiv, Marten Runge, CJ, Robin Burnett and Paul Berry for information in this section.