Ministers have given the go ahead for the HS2 project to enter the construction phase.

HS2 Ltd, the Government-owned company developing the high speed railway, was given approval to issue a notice to proceed to firms contracted to design and construct bridges, tunnels, embankments and viaducts for phase one between London and Birmingham.

Prime Minister Boris Johnson gave the green light for HS2 in February despite it running tens of billions of pounds over budget and several years behind schedule.

The Government-commissioned Oakervee Review warned that the final bill could reach £106 billion at 2019 prices.

HS2 Minister Andrew Stephenson said the Government’s main priority is combating the spread of coronavirus but “we cannot delay work on our long-term plan to level up the country”.

He went on: “This next step provides thousands of construction workers and businesses across the country with certainty at a time when they need it, and means that work can truly begin on delivering this transformational project.”

HS2 Ltd chief executive Mark Thurston said the decision gives “an immediate boost to the construction industry” as it ensures contractors and their supply chains can have “confidence that they can commit to building HS2”.

The UK’s construction industry employs more than two million workers and produces about 6% of the country’s total economic output.

Many building sites, such as those developing Crossrail, are closed due to the Covid-19 lockdown, while some are open with fewer workers than normal to comply with social distancing guidelines.

A campaign was launched to close all building sites because of the threat to workers.

Four joint ventures were awarded main works civil contracts worth a total of £12 billion for phase one of HS2 in July 2017.

They are:

– SCS Railways (Skanska Construction UK, Costain and Strabag)
– Align joint venture (Bouygues Travaux Publics, Sir Robert McAlpine and VolkerFitzpatrick)
– EKFB joint venture (Eiffage Genie Civil SA, Kier Infrastructure and Overseas, Ferrovial Agroman and BAM Nuttall)
– BBV joint venture (Balfour Beatty Group, Vinci Construction Grands Projets, Vinci Construction UK and Vinci Construction Terrassement)

Shares in Costain, which is listed on the London Stock Exchange, jumped by around a third on the news that a notice to proceed has been issued.

Preparatory work at some HS2 sites remains paused following a review of what operations can be carried out in accordance with coronavirus guidance.

But HS2 Ltd said the four joint ventures will “start work immediately” on detailed designs, site preparation work and issuing sub-contracts.

The companies involved are applying conditions such as ensuring a minimum clearance between all personnel of two metres, having facilities for regular hand washing and single occupancy of all vehicles unless agreed in advance.

Eamon O’Hearn, national officer of the GMB union, called for rigorous standards to protect workers.

He said: “GMB wants to protect workers’ jobs, health and pay. HS2 is a project of national importance but the safety of its workforce and supply chain must be the overriding priority.”

Phase one of HS2 was due to open in 2026, but it could be 10 years later before full services operate.

Passenger trains between Old Oak Common in west London and Birmingham Curzon Street are due to start running between 2029 and 2033, with the line extended to London Euston between 2031 and 2036.

The DfT and HS2 Ltd’s estimate of the cost of phase one ranges from £35 billion to £45 billion.