Medway Viaducts
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| 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 High Speed 1 |
| 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 |
There are three Medway Viaducts, two of which carry the two carriageways of the M2 motorway. The other viaduct carries High Speed 1 across the River Medway near Rochester in North Kent.
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[edit] M2 Motorway viaduct (old)
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 (actually a small service road) was placed on either side of the bridge 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 lies within the central reservation at both ends, leaving only the north-facing footpath. Prior to this, the bridge had been undergoing extensive refurbishment and strengthening. This included the said footpaths being reduced in width and thus making the bridge narrower. The central span, which was made of concrete beams, was replaced with steel girders. The concrete beams were lowered down on to a river barge. Presumably, these would be broken up on land.
As part of the M2 widening, the bridges are now fitted with street lighting. This was the first time the bridge had lighting on it.
An image of the bridge without the central span can be seen on the link below.
The bridges pass over two railway lines: The Medway Valley Line (to Paddock Wood) and Chatham Main Line (to Victoria).
During the construction of the new bridges, a support boat was positioned in the river. This is presumably as a safety requirement, should a member of the workforce get into difficulty near the river.
[edit] M2 Motorway viaduct (new)
This bridge is the newest bridge to cross the River Medway at this point.
In 2003, this particular bridge won the Concrete Society’s Civil Engineering Category award for, ‘outstanding merit in the use of concrete’. It was presented to Doka UK Formwork Technologies.
A small plaque can be seen on one of the upright support legs, on the Strood side.
A link below shows the winning certificate.
[edit] The rail-link viaduct
The western bridge carries the high speed rail link that connects London with the Channel Tunnel. This is sometimes referred to as High Speed 1 (HS1).
The rail bridge is 1.3 km long, making it the longest high-speed rail span in the world. The viaduct is a multi-span structure, with typical approach spans of 40.5 m, spanning the River Medway with a central navigation span of 152 m. The viaduct substructure is of 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. (More orthodox vertical supports could, in a worst-case scenario, topple like dominoes.)
The bridge deck was pushed out from each bank of the river during construction, using hydraulic pistons.
On 4th September 2007, Eurostar 9021 driven by Neil Meare crossed the viaduct at up to 200 miles per hour, during the record breaking inaugural run from Paris Gare du Nord to London St Pancras.[1]
[edit] References
[edit] External links
