Tunnels designed by Arup were “incapable of implementation”, said Tilbury Douglas in the defective designs claim
A defective designs claim by Tilbury Douglas asking for £6m from Arup has been rejected.
Court of Session inner house judge Lord Malcolm declined Tilbury Douglas’ claim, saying that there “was more than enough [evidence at the time] to alert those involved” to the need to further investigate the designs.
Tilbury Douglas appointed Arup to deliver civil and structural engineering services for the early phases of a mixed-use development on the former Haymarket railway yard in central Edinburgh.
The latest stop in a twelve year story
Then called Interserve, Tilbury Douglas was part of a joint venture with Tiger Developments in 2012. Interserve were the principal contractor on the Haymarket development, which covered five buildings with office, retail and hotel space.
Arup were hired to provide services around the enabling works, including the tunnel designs. This included reinforcement of the northern tunnel brickwork, during works to remove the top of the tunnel, also known as the overburden.
Stitch grouting was implemented to reduce the risk of the brickwork collapsing, but concerns were soon reported by Bam Nuttall contractors working on that section.
Further investigation by Bam and Arup confirmed the need for repairs, identifying issues with voids in the northern wall and grouting.
Tilbury Douglas accused Arup of not accounting for the likely presence of voids in the north tunnel and failing to make allowance for the annular and interstitial grouting that would be required as a result. It valued the costs of necessary repairs and delays to the work as £6m, which it charged to Arup.
A previous judge let the defective designs claim proceed, but was now said to have “erred in his reasoning”
The enabling works were then delayed by six weeks, as Bam sought out over £1m for the extra work.
Saying that Arup had “erroneous and overly optimistic assumptions” about the tunnel wall strength, Tilbury went on to say that Arup had “failed to exercise the skill, care and diligence expected of a competent civil and structural engineer”, breaching its contract.
“Arup produced a design which failed to reflect accurately the physical conditions of the site and which was therefore incapable of implementation.”
Tilbury Douglas registered the defective designs claim in July 2019, over five years after the issue came to light, but claimed that they had only done so eight months past the deadline as Arup had assured them that there were no problems in the tunnels.
The first judge agreed with this point and allowed the case to proceed, but Lord Malcolm ruled that the previous judge had “erred in his reasoning”.
Tilbury Douglas should have examined Arup’s designs at the earliest opportunity, according to the judge
Ruling that Arup was simply “expressing confidence in their design”, Lord Malcolm said it was “up to Tilbury whether to accept those assurances, or at least not question them”.
“In the absence of proof of an error, it is difficult to elaborate on how reasonable diligence might have avoided or corrected it [the alleged mistakes by Arup],” he said.
“On the assumption that the design was deficient, had Tilbury seen a need to explore the issue, on the face of it there was more than enough to alert those involved to the need to be less accepting of Arup’s statements.”
