Medway Viaduct
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| Carries | Original:4 lanes of M2 plus hard shoulder & Bridleway New: 4 lanes of M2 plus hard shoulder Rail: 2 tracks of Channel Tunnel Rail Link |
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| Crosses | River Medway |
| Locale | Cuxton, England |
| Design | Cantilever |
| Longest span | Original: 152.4 metres (500 ft) New: Rail:152.4 metres (500 ft) |
| Total length | Original: 997.3 metres (3,272 ft) New: Rail: 1,300 metres (4,265 ft) |
| Width | Original: 34.44 metres (113 ft) New: Rail: |
| Clearance below | Original: 35.5 metres (116 ft) at maximum New: Rail: |
| Opening date | Original: September 1963 New:2003 Rail: 2002 |
The Medway Viaduct is the name of a collection of 3 neighbouring bridges that carry two carriageways of the M2 motorway and phase one of the Channel Tunnel Rail Link across the River Medway near Rochester in North Kent.
[edit] M2 Motorway
A six lane (two London bound, two coast bound, two hard shoulder) bridge was built in the 1960s as part of the construction of the M2 motorway. In addition a footpath was placed on both sides of the bridge (actually a small service road) as part of the North Downs Way, offering panoramic views of the Medway Valley.
As part of the recent M2 widening, a second bridge was built alongside (to the south) to carry the London bound carriageways (four lanes and a hard shoulder). The existing bridge was rebuilt into a four carriageway road (coastbound). The south "footpath" is now closed (as it's in the central reservation at both ends), leaving only the north facing footpath.
[edit] Channel Tunnel Rail Link
The western bridge carries the high speed rail link that connects London with the Channel Tunnel.
The rail bridge is 1.3km long making it the longest high speed rail span in the world. The viaduct is a multi-span structure, with typical approach spans of 40.5m, spanning the River Medway with a central navigation span of 152m. The viaduct substructure is reinforced concrete pier columns supported on bored piles. A unique feature of the columns is that they are in a "V" shape. This is to provide greater lateral support and stability in the event of two high speed trains using their emergency brakes. If more orthodox vertical supports were used the bridge could in a worst case scenario actually topple over like dominoes.
The bridge deck was pushed out from each bank of the river, using hydraulic pistons, during construction.
