All diesel HGVs on the project will need to be powered by the cleanest available Euro 6 engines, going beyond current standards.

Also HS2 is insisting construction equipment used along the route’s entire length meets the EU Stage 3b standard, rising to less-polluting Stage 4 in 2020.

In the capital’s Congestion Charge Zone, HS2 already demands its contractors comply with Stage 4. This will rise to Stage 5 next year, staying one step ahead of the city’s own emissions standards.

HS2’s director of environment, Peter Miller, said: “HS2 is more than a railway. We are leading the industry in vehicle emission standards by exceeding London’s construction industry standards and extending them 345 miles across the country.

“We are determined to use the project’s scale and duration to help cut the release of harmful combustion engine emissions by stipulating contractors building Britain’s new high speed rail network use the cleanest vehicles and machinery available.

“By setting new vehicle emission standards for contractors we will contribute to efforts to improve air quality; and leave a legacy of a new fleet of low-emission HGVs and construction equipment to work on future projects.

“We also hope our rules influence local authorities along the route to follow HS2’s lead and introduce exacting emissions standards in their area, which would benefit huge swathes of the country,” he added.