Our client had been asked by Salford City Council to monitor any movement of the Lowry Bridge, a 90m long vertical lift bridge spanning the Manchester Ship Canal between Salford and Trafford in Greater Manchester. He asked us to provide a suitable solution.
As part of a general facelift, the 23-year-old bridge was to be re-painted. For the lower parts of the bridge a scaffold cradle was to be constructed beneath the bridge and moved along in stages to obtain suitable access.
We had to determine the movement caused by the cradle to make sure that no serious distortion of the bridge was occurring.
A control network of approximately 8 retro markers was established, surrounding the bridge, to an accuracy of 1mm. Baseline measurements were taken to establish levels to 1mm accuracy, at approximately 6m intervals along the bridge deck by sighting the top of the bridge footway. These exact sight lines were then repeated during bi-weekly visits with any adjustment needed in the vertical to record the new level at each point.
The results below highlight how the bridge flexes with respect to where the cradle is positioned. These amounts were expected by the client and not deemed to be of significance. Readings were taken at the end of the works which showed that the bridge had (almost) returned to its original position.
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