The Balerno line was a short loop railway in the southern suburbs of Edinburgh, Scotland.

It was 6 miles in length, leaving the main Caledonian Railway Edinburgh to Carstairs line at Slateford, and rejoining it at Ravelrig.

It was built by the Caledonian Railway mainly to service the many manufacturing enterprises situated along the upper Water of Leith, and passenger trains also ran.

The opening of the Union Canal in 1822 ameliorated the problem somewhat, even though it passed three miles (5 km) away to the north.

The Edinburgh line of the Caledonian Railway from Carstairs ran south-west to north-east through open countryside when it was built.

With the removal of excise duty from esparto in 1861, the substitution of the grass fibre for rags stimulated the manufacture of paper.

The company could see that it was not feasible to build the line at the time, and on 22 October 1867 the Board decided to abandon the work.

[5][6] The following year the Board considered that the money markets had calmed, and they applied to renew the authorisation of the branch.

This time they wished to extend it to Ravelrig, rejoining the Carstairs main line there and forming a loop.

[12] The gradients were steep, and the Caledonian ordered a special design of 0-4-4T locomotive to handle trains on the line.

[16] In the inter-war period, the popularity of countryside visits for leisure purposes increased considerably, and the natural beauty of the places beside the line, notwithstanding the significant industrial presence, led to satisfactory loadings at weekends.

Barrie, writing in 1935, said, "the district [was] much in favour with the citizens of Edinburgh as a pleasantly situated 'dormitory', while its proximity to the Water of Leith makes it a favourite summer resort with picnickers and ramblers.

Six coaches... normally form a train set, which is strengthened to eight vehicles at the morning and evening peak periods...