Austrian construction firm Porr AG said it was to sign a 1.89-billion euro ($2.5 billion) contract to build one of Doha's new metro lines, as part of a consortium with two Qatari partners, SBG and HBK.
This was the second such contract for European firms in three days.
The "Green Line" deal was to be signed in mid-June with construction on the 16.6-kilometre (10.3-mile) metro line–one of four planned in the wealthy Gulf state–and six stations due to take five years, Porr said in a statement.
Newspaper reports had said last week that Qatar Rail had awarded four contracts worth a total of $8.2 billion in the first phase of construction for the Doha Metro, including to Porr. But they gave no breakdown on the value of each contract.
Porr said it would be responsible for 50% of the "Green Line" project, worth EUR945 million. It added this was the biggest contract in its history.
"Our team on site has worked closely together with the Executive Board in order to achieve this milestone in our company's history thanks to their extensive experience and in-depth market knowledge," Chief Executive Karl-Heinz Strauss said.
The Doha metro project is part of Qatar's "National Development Plan for 2030" and also comes as the Gulf state prepares to host the FIFA World Cup in 2022.
Previously, French group Vinci SA (DG.FR) said it had won a EUR1.5 billion tender for the Doha metro, as part of a consortium led by QDVC, a joint venture between Vinci and investment firm Qatari Diar.