Contractor Macmahon has won $115 million worth of work as part of a consortium with Leighton to construct part of an express rail link between Hong Kong and mainland China.

Leighton Asia will build a 7.6 kilometre twin-track tunnel between Tse Uk Tsuen and Shek Yam, on the Hong Kong section of the rail link, plus a ventilation shaft and access points.

The overall contract is worth $463 million.

Macmahon will help Leighton with the drilling and blasting.

The rail link will provide high speed rail services between Hong Kong and mainland China, with the Hong Kong section of the project to be underground.

The work will begin later this month and is scheduled for completion in 2015.

Macmahon chief executive Nick Bowen said the project highlighted Macmahon's emerging international growth opportunities.

Macmahon shares were up 3.5 cents, or 4.67 per cent, to 78.5 cents at 7.15am after emerging from a trading halt while Leighton shares were up 23 cents to $39.23.