Spencer Group completes major Forth Road Bridge repairs

13th Feb

High-level bridge works specialist Spencer Group has delivered a hugely
challenging project to complete repair works which followed a fracture that
caused the closure of the Forth Road Bridge.

A team from the Hull-based engineering business has carried out works to replace truss end links that connect the bridge deck to the towers.

The project had its origins in the discovery, in December 2015, of a
major fault on the crossing, which spans the Firth of Forth, connecting
Edinburgh to Fife.

One of the eight truss end links on the bridge was found to have
fractured, causing the bridge to be closed completely for more than three weeks
while urgent repairs were carried out.

A temporary splint was applied to the fractured link, followed by a
permanent structural repair to that area. Bridge owner Transport Scotland
subsequently decided to replace the other seven key links and, following a
tender process, selected Spencer Group, an industry leader in complex
engineering projects on major structures, for the works.

The £10m scheme has involved cutting out the truss end links and
replacing them with a unique new sliding bearing system. It has required a
series of complex works to be delivered to a part of the bridge which has
limited accessibility and was never designed with replacement in mind.

The project posed multiple challenges, with the Spencer team working in
confined spaces within the main towers and manoeuvring large new structural components
to precise tolerances.

The replacement bearings were delivered to the bridge from a workboat,
so the works had to be co-ordinated with tide times within the busy Forth
estuary.

Ensuring effective communication via two-way radios was crucial, with
engineers working below the bridge deck having to contend with significant
noise and vibration as traffic passed above them.

Despite these challenges, Spencer Group team delivered the project
successfully with minimal impact on normal bridge operations and with traffic
flowing throughout.

Spencer Group managing director Gary Thornton said: “We’re delighted to have completed this important project to maintain the structural integrity of the Forth Road Bridge and to add it to our extensive track record over many years of delivering critical, high-level works on landmark crossings.

“The project
showcased the expertise we bring to works such as this, which pose a range of major
challenges. The solutions we put in placeensured critical components were replaced without having to interrupt
traffic flows at any time.”

Spencer Group bridges projects manager James Barnes said: “This project has been particularly challenging in relation to access because the truss end links and the new bearings we have fitted are below the bridge deck, about 40 metres above the water.

“No permanent access was in place, so we installed a temporary access
platform to allow our personnel to reach the location of the works.

“With our supply chain we have fabricated over 200 tonnes of new steel
and joined it to the existing structure in some very inaccessible areas.

“The pieces that we cut out to replace were 7-8 tonnes in weight and
some of the heaviest lifts have been up to 16 tonnes. All the pieces have had
to be lifted onto the bridge deck or lowered to the workboat, so there have
been major lifting, hoisting and access challenges that had to be overcome.”

Amey, the long-term maintenance contractor for the Forth Road Bridge, represented
Transport Scotland on the project.

Angus Bruce, Amey’s major bridges manager, said: “A key requirement of the project was for the contractor to have previously worked on long-span, cable-supported bridges and Spencer Group is one of only a handful of contractors to have this experience.

“Spencer Group is a very experienced contractor, with expertise in managing
this type of work, assessing the issues involved and delivering the project
safely.”

Spencer Group is one of the UK’s leading privately-owned
multi-disciplinary engineering businesses and is
renowned for its world-class expertise in long-span bridge repair and
refurbishment, having delivered a series of projects in this field over the
past 15 years. Flagship Spencer Group schemes include the world’s largest project
to dehumidify existing bridge cables, on Denmark’s vast Great Belt crossing.

The company is currently delivering another essential maintenance
project, on the Humber Bridge, close to Spencer Group’s headquarters in Hull.
This project involves the design and construction of a bespoke access platform,
which will allow engineers to access, inspect and replace the bridge’s
“hangers” – the super-strength, high-tensile
steel ropes that suspend the bridge deck from
the main cables.

BusinessWorks Hull & East Yorkshire summer 2021

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