Costs to repair Spaghetti Junction have soared to more then £4.5m in 2008.
The junction was opened in 1972
Birmingham's complex interchange, where the M6, A38 and the A5127 meet, is 35 years old and is one of the most famous landmarks in the West Midlands.
The Highways Agency said the costs were higher because it had signed a one-off maintenance contract. The figure was five times higher than in 2007.
Last summer motorists voted the junction as the UK's best-known sight seen from a motorway.
The junction was heralded as the future of motoring when it was opened in 1972 by the then environment secretary, Peter Walker.
It cost £10m to build and is held up by nearly 600 concrete columns.