Scottish Water has tunnelled under a railway line near Kilmarnock as part of a project to install a major new water main.

A tunnel boring machine was used to drill the 132m long, 1.5m wide tunnel beneath the Kilmarnock to Dumfries railway line near Whinpark Farm.

Engineers used 53 concrete rings, each 2.5 metres long and weighing 4.9 tonnes, to support the tunnel, which has been described as the "missing link" of a 13-mile-long stretch of water main from the Amlaird Water Treatment Works to Highlees district service reservoir in East Ayrshire.

The tunnel was installed as Scottish Water moves forward with the second phase of a £120m investment to benefit more than 200,000 people and businesses in much of Ayrshire and parts of East Renfrewshire.

Customers across a large part of Ayrshire currently receive their water from a single source, the Bradan Water Treatment Works, south of Straiton in South Ayrshire.

The water is supplied to customers' taps via a 34-mile-long trunk water main installed about 50 years ago from the Bradan plant to the north of Irvine.

The construction of the new strategic water main, which is expected to be completed in 2020, will connect Bradan to the network served by the Milngavie and Balmore water treatment works north of Glasgow.

Sean Lavin, senior construction manager, said: "We are continuing to make good progress with the project and this latest piece of work to install the tunnel was a very important part of that.

"We are delighted to have completed the work under the railway, which involved a lot of careful planning and close liaison with Network Rail and Scottish Water Special Services, who deal with land, environmental and planning issues."