New tidal gauge destined for The Wash
The project was to model a new tidal gauge destined for The Wash, Lincolnshire, for Four-Tees Engineers. This gauge is a means to measure tides, assist with collecting data on climate change and help assess the future impact of flooding and the risks of it.
The tidal gauge sits on a 2m diameter steel pile, fixed approximately 21m below the seabed level. The top of the pile is approximately 2m above mean sea level. It comprises a 13.5m long, 2.2m diameter steel sleeve with all ladders, platforms and braces fully welded to the outside of the sleeve. The whole assembly slid over the top of the pile and was fixed with clamping rings with precise positioning.
A 9m wide hexagonal top platform is bolted to the top of the pile sleeve and sits 11m above mean sea level. The top platform, due to its size, was fabricated in two fully welded sections and bolted together on site prior to lifting by crane barge onto the top of the pile sleeve. The top platform supports all of the gauge’s monitoring equipment.
Due to the challenge and cost of installing at sea, the whole gauge was designed to fit together in as few lifts as possible. As such, as many items as possible required fixing to the pile sleeve and top platform assemblies prior to lifting. All handrail, flooring, kickflat, ladder sections and berthing points all required fixing in situ prior to lifting into place via crane. The flooring needed modelling in an exact format so that the floor panels could be laid accurately onto the steelwork with positive fixings. One of the big challenges was modelling the flooring to such a precise arrangement.
Various curved inspection covers and openings were required in the pile sleeve to allow monitoring of the pile. The only way these could be plotted to the correct accuracy was to import a 3D reference model from the design team for us to develop the covers around. Also, we had to model the cable trays, floor hatches and anti-vandal security measures to the ladders along with all hinges, locks and split pins.
Due to the fact that the gauge is constantly rising and falling with the tide, various tolerances were required to allow for the mooring of any boats visiting the gauge along with measures to stop damage from the boats bashing into the gauge when moored.
Tekla ensured transparency and accuracy across this one-shot project
The drawings and details received from the design team were thorough and accurate although until such projects are modelled and ancillary items such as flooring and handrails are modelled, clashes and problems are not fully realised. There was a constant collaborative effort between all parties to resolve these problems once they were known via use of IFC models, screenshots and DWGs.
The fabrication drawings needed precise weld notes and details to ensure the structure was correct prior to installation, as there is no scope for modifications once erected. This was a one-shot project with no room for errors!
Tekla was an ideal program for this project due to the extensive means of modelling bespoke parts, as well as the multiple ways of producing design information for review and comment. Phasing was particularly useful on this project as well as object representation. Everybody could see exactly what they were getting and to a high degree of accuracy. Such a project would be very difficult to achieve using 2D software.