After careful negotiation with Graham Construction, CDC was awarded the contract for the demolition of this nine span road bridge over nine railway lines in Croydon in June 2014.
The brief was to demolish sections of the bridge over a series of weekend possessions between August and November, ensuring the continued movement of trains under the spans not being demolished. There was also a high level gas main supported on a series of trestles running along the south side of the bridge which
On the east side of the bridge, Spans 1-3 were over waste ground as a result of earlier track removals. The first task over the initial August weekend possesson of the line under Span 4 was therefore to separate the total bridge into two sections to enable Spans 1-3 to be demolished during normal working hours. Span 4 was a concrete deck supported by cast insitu concrete beams. Once the possession was in place, a protective mat was laid over the track and working from the north side, the steel parapet was cut into sections by Topmen Burners with two Volvo EC210C Machines carefully holoding each section, before lowering the to the ground for further processing and removal. The deck was then progressively demolished, with the section of deck beteween the edge beam and second beam being broken down, followed by the edge beam itself and this sequence being repeated across the deck width. All rubble was cleared away, the track protection lifted and the track handed back.
Spans 1-3 were therefore able to be demolished safely by the machines working perpendicular to the live tracks back towards the east abutment. These spans were all similar, being steel beams with brick jack arches. Part of the eastern abutment was also reduced to receive the new structure.
Over two later weekends, Spans 5 and 6 were demolished during the first and Span 7 over the second. These spans were similar to span 4, but all had to be demolished from the eastern side as the tracks under Spans 8 and 9 were live, creating a huge track protection mat to ensure safe machinery access across the remaining lines.
Span 8 was next and this time we were able to approach it from the westernside, although the track protection still had to go over Span 9 and we had the risk of an engineering train wanting access at any time! This span was steel beam with brick jack arches, so the jack arches were broken doen by the machines reaching up and over to break from the top and then the steel beams were lifted out.
The one benefit we had was that the track protection over Span 9 was able to remain in place until the following weekend when we returned and demolished the final span and reduced the western abutment down to the level required by our client for the reconstruction.
Every section of the work was completed within the allotted possession time and our client was able to follow on seamlessly with the construction and launch of the replacement bridge.
This project was such asuccess for us both that Graham Construction has already engaged us on another large project starting in early 2016.