Tony Dempsey

Tony Dempsey

Director
Client
Farrans Victor Buyck Construction JV
JV Partner
Buro Happold Consulting Engineers
Location
Sunderland, UK
Value
£120m
Market

Summary

Roughan & O’Donovan provided consultancy services - from tender through to completion of construction - for the permanent works structures on this large scale infrastructure design and build scheme.

Awards

  • Transport Project of the Year at the British Construction Industry Awards 2019
  • Overseas award winner at the Association of Consulting Engineers of Ireland (ACEI) Design Excellence Awards 2019
  • Geoscience Ireland award winner at the Engineers Ireland Excellence Awards 2018
  • Project of the Year: Engineering, Construction and Infrastructure at the Association for Project Management Awards 2018

Solution

The bridge is 340m long and comprises a 24m-wide steel concrete composite deck, supported by a 1,550 tonne, 105m-high A-frame pylon, with sections of concrete and concrete/steel composite construction. 

It stands apart from traditional cable-stayed solutions in two ways:

  1. Its central pylon was fabricated in one piece off site and transported by sea to the bridge site
  2. Its deck was assembled in two sections alongside the bridge and launched in two separate phases across the river 

These innovations provided substantial benefits, in terms of construction and whole-life maintenance costs, to our client.

  • 105

    Height in metres of the bridge pylon
  • 1550

    Weight in tonnes of the bridge pylon
  • 15

    Number of hours it took to raise the pylon

Structures

Major and minor structures designed to facilitate the scheme construction included:

  • 140m long x 25m wide piled basal mattress
  • Reinforced earth wall retained embankment up to 9 metres in height
  • Retaining walls of sheet pile, contiguous bored pile and reinforced earth construction

Challenge

The raising of the 105m high, 1550t steel/concrete pylon marked the culmination of two years of design and planning and 12 months of fabricating. A highly complex process, it required stringent geometric control and monitoring procedures.  

The pylon was raised into the vertical position using cables.  Temporary hinges were provided on top of the concrete ‘tusks’ at the base of the pylon to facilitate the lift.  A temporary back mast was fitted to the pylon and hoisted vertical from a barge using 4 number 450t capacity strand jacks. 

Not one critical trigger level was reached during the launch, which is testament to the joint venture's expertise in the design and interface co-ordination of complex permanent and temporary works on major bridge structures.

Services provided:

  • Bridge engineering design
  • Structural engineering design
  • Geotechnical
  • Temporary works
  • Electrical
  • Lightning protection
  • Road engineering design services