Project Moorgate Shaft Access Platforms
Supply and install tunnel access platforms within shaft
A 30m deep access shaft had been excavated by a previous Crossrail contractor to enable various tunnels to be excavated between Liverpool Street, Moorgate and two new East/West Crossrail running tunnels. The top down construction resulted in a large jetty structure in the middle of the shaft that would require dismantling and removal at a later date, but a series of heavy duty platforms would be required in order to stage the tunneling works.
2016
Year
£1,500,000
Overall Value
BBMV/CROSSRAIL
Client
Tony Goble
Contact
The Challenge
An acceleration in the Crossrail project meant that the Tunnel Boring Machines would be at the site six months earlier than planned and the fabrication and erection of working platforms was on the critical path to allow the TBM’s to transit the site for their onward journey. There existed only an outline scheme and in order to meet the deadline we had to procure materials at the same time as our engineers were completing the design and connections of the structural platform members.
Working over the Christmas period and ensuring 24 hour working, including bank holidays, we were able to maximise production on site and ensure the minimal impact to the tunneling and interface works. Our fabrication yard required to be open during this time also as materials would require testing, delivery and installation as the site works progressed. Our specialist site welding teams were drafted in to ensure welder/Fabricator cover and to keep on programme.
Modular Design
Spoor-Tech took an early lead in the design and practical advice on construction within a small assembly area and already congested shaft. We identified at the outline stage that the platforms could be designed as a modular system and we could assemble sections at street level to be dropped into place and bolted to the main structure. This worked to good effect and although the sections when assembled in the area at street level, weight in excess of 14t, there was a huge advantage to freeing up crane time from holding individual members in place for bolting at the work face.
An acceleration in programme meant that there was only an outline scheme for the works and our engineers would have to offer input to the design and construction sequencing of the platform works. Hundreds of connections required detailing and sequencing to ensure the assembly was kept on track.
The minimal timeframes for installation meant that with only weeks to mobilise Spoor-Tech were required to undertake the works during a 10 day window over the 2014/15 Christmas period. With a minimal mobilisation window, we had to clear a street level assembly area, mobilise large items of plant, welfare and storage to site and procure access equipment and temporary works items for an ever developing scope of works.
That Jetty
Dismantling the jetty required a complicated choreography of cutting burning and disassembly, as all members had been welded in-situ as the shaft sinking progressed.
Gas cutting would need to be undertaken from a man-riding basket to free up individual sections of the jetty platform.
Of major benefit to the client was the fact that all our staff are inducted and experienced on this particular Crossrail contract through our previous works.
