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Tamar Bridge Hanger Bolt Replacement

Following their very successful collaboration on the M48 Severn Crossing Main Cable Inspection project, Eadon Consulting once again teamed up with American Bridge International to provide design support for the high level and truss level access platforms. In addition to this Eadon were also responsible for the temporary hanger cable arrangement to unload the permanent hangers and allow the bolts to be replaced.

Key facts

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Location

Tamar Bridge

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Client

Tamar Crossings

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In Partnership with

American Bridge International

The Tamar Bridge, which spans the River Tamar between Plymouth and Saltash, was opened in 1961. Over the last 20 years the suspension bridge has undergone major reconstruction and strengthening works, and in 2017 work began to replace the cable band bolts and hanger cable bolts.

Tamar bridge hanger bolt temporary collar

Both the High Level and Truss Level Access Platforms consisted of a bespoke arrangement using equipment supplied by ALPS. Eadon worked closely with ALPS to verify their arrangements, including lifting and lashing equipment, under all credible loading conditions. Once the design and verification was complete Eadon organised an independent Category 3 (CAT III) check of the design to comply with Highways Authority requirements for type P temporary works.

Following completion of the design Eadon were responsible for developing the testing schedule in accordance with BS EN 1808, and also for carrying out the load testing at ALPS works.

The second part of Eadon’s contract was as Designer for the Unloading System, which is used to temporarily relieve the load of the bridge truss from the permanent deck hanger and cable band being worked on.

The Unloading System consisted of two temporary hanger arrangements, one either side of the permanent arrangement. Each had a temporary cable band, which was designed by Eadon Consulting. Dorman Long supplied temporary hanger strand and jacking equipment along with a bespoke arrangement for supporting the bridge truss. The design for the whole system was verified by Eadon, as well as a Category 3 check commissioned.