SUBMERGED TUBE TUNNELS
Key personnel from Geodetic were heavily involved with the consulting engineers responsible for the A55 Conwy Crossing, a submerged tube tunnel project crossing the River Conwy in North Wales.
The biggest and most challenging contract on the A55 Improvement scheme was the Conwy Crossing which was opened by the Queen on 25th October 1991. The scheme relieved the bottleneck in the walled town of Conwy. Centrepiece of the scheme is the crossing of the Conwy Estuary by Britain's first immersed tube road tunnel, approached by cut and cover sections to east and west.
Geodetic designed and developed several software solutions to aid engineers. Included in these developments were:
Least Squares Adjustment package designed to automatically download theodolite data, process it and graphically present the results of where alignment work was needed on each facing seal edge of the six tunnel elements.
Floatation Analysis package designed to allow input of several variables including salinity, ballast, sea state, atmospheric data and output forecasted floatation characteristics of the floated out tunnel elements.
Tunnel Placement package designed to take real-time theodolite data from two sources and compute and display the horizontal and vertical alignment of the tunnel elements (six at 30,000 tons each) to ensure they were being placed correctly when compared to the theoretical design lines built into the package. Pictures by Gwyn Hughes.
One of our engineers (on the left) checking alignment analysis of the floated out tunnel using linked theodolites and mobile units running the specially designed and developed software by Geodtic staff. Picture by Gwyn Hughes