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Humber Bridge High Level Cable Crawler Gantries

Eadon Consulting carried out the detailed design of the high level platforms required to carry out the majority of the works for the Humber Bridge Main Cable Dehumidification Project by The Spencer Group. The movable gantries acted as a working platform to allow the main cables to be heat sealed in a polymer wrap along their entire length. Injection and exhaust sleeves, also designed by Eadon, were fitted at various locations to allow for dehumidified air to be pumped through the cables. The dry air pick-ups any moisture en-route and reduces and maintains the humidity level to below 40% preventing the cables from corroding.

Key facts

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Location

Humber Bridge

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Client

Humber Bridge Board

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In Partnership with

The Spencer Group

The gantries were designed specifically for the geometry of the Humber Bridge, in particular the cable on the Hessle side span of the bridge has a slope of 27 degrees (1 in 2), steeper than any of the other suspension bridges in Britain. The gantries remained on the cable in all weathers and were designed for the particularly harsh conditions at the top of the towers where the design gust speed is 120mph.

The 27m long structures were designed with the aid of STAAD Pro structural analysis package to BS5950-1, Structural Use of Steelwork in Building, using safety factors from BS EN 1808, Safety Requirements on Suspended Access Equipment. The travelling gantry mechanisms were designed using BS 2573, Rules for the Design of Cranes.

The project took place in 2010 and was scheduled for a period of two years, however it was completed in just 12 months. Several factors contributed to the success of the project, a significant one being down to the design of the gantries carried out by Eadon.

The 2010 Yorkshire and Humberside Constructing Excellence Regional Award for Innovation was given to The Spencer Group for the Humber Bridge gantries.