CH2M pulled out of a controversial £170m contract yesterday to design the second phase of HS2, citing "ongoing speculation", but the saga may not be over just yet.
Losing bidder Mace, which queried CH2M's win and led to HS2 delaying the contract award to answer its concerns, has said the whole tendering process should be restarted. The British construction firm said it was still mulling legal action.
A Mace spokesperson said: "With so many questions being asked by the public and parliament, the only sensible thing to do now is to look at the whole tender process again."
However, HS2 said it has no plans to cause further delays by re-tendering and has already opened discussions with the second-placed bidder, Bechtel.
"We are confident that our processes were fair and robust," an HS2 spokesperson said.
Mace will meet HS2 tomorrow where it said it will seek answers to the firm's "numerous questions about the entire procurement process".
"It’s important to note that conflicts of interest was only ever one element of our concerns," the spokesperson added. "We have never brought a case to the High Court or seen a procurement process run like this. We continue to closely review our next steps with our legal team and don’t rule anything out.”
Concerns had been raised over potential conflicts of interest, with HS2 appointing CH2M's Europe boss Mark Thurston as its new chief executive at the beginning of the year. Thurston replaced Roy Hill, who was seconded from CH2M too.
When Thurston was appointed, TaxPayers' Alliance chief executive John O'Connell said "the revolving door" between HS2 and CH2M meant "serious questions need to be asked as to how contracts can be awarded fairly".
CH2M said yesterday it was withdrawing its interest in the contract due to "protracted delays and ongoing speculation".
The US engineering consulting firm said: "CH2M has demonstrated all appropriate measures taken throughout to ensure the integrity of the procurement process.
"Notwithstanding these efforts, we have taken the decision to alleviate any further delays to this critical national infrastructure project which could ultimately lead to increasing costs to UK taxpayers, as well as to our firm."
The rail project has also been dealt a blow by the confirmation that David Prout, director general of HS2, had resigned. Prout is leaving to take up a position at Oxford University in September.