Load-out and installation of a bascule bridge, UK
ALE has completed the load-out and installation of the Tower Road bascule bridge, weighing 445t, in Birkenhead, UK.
Prior to the load-out, ALE weighed the bridge to check that the weight and Centre of Gravity (CoG) were as specified.
The tug boat and barge, along with its pumps, winches and link span, were prepared onsite several days in advance. ALE also rigged 20 axle lines of SPMT in a configuration of 2 x 2 file 10 ready for the load-out.
ALE installed support stools under the bridge’s main girders and carried out a trial lift with the SPMTs the day before the load-out. Once the actual lift was complete, the stools were removed. ALE rotated the bridge 90 degrees to line it up with the barge’s link span and transported the bridge onto the barge. The load-out was carried out gradually alongside the ballasting operation.
A support tug manoeuvred the barge from its mooring location in the East Float to the East Lock and it was then moored to the quay edge, where the ballasting operation was carried out.
ALE rotated the bridge 90 degrees to position it correctly for the installation and manoeuvred it to the edge of the barge. The bridge was lined up over bridge support tracks.
The lock gates were then closed and the water level in Alfred Dock was slowly lowered.
ALE used a combination of the lowering water level and the stroke of the SPMTs to land the bridge on the support track, with a 2mm tolerance.
Once the bridge landing was complete, the winches were disconnected and the barge was moored on the quayside of Alfred Dock in preparation for the demobilisation.
ALE performed the load-out in approximately one hour and the entire load-out and installation operations were completed over two days.