A piece on a proposal in 1898 to construct two railway lines on Lewis can be found here: http://hlrco.wordpress.com/2010/10/05/railways-of-lewis-harris/
There are no ‘rail’-associated returns from the 1901 census for Stornoway so, even if the scheme was still ‘alive’ then, I can add no more information.
An industrial line was that associated with the earlier Peat Oil project of Sir James Matheson can be read here: http://direcleit.blogspot.com/2010/03/lewis-chemical-works.html In the 1871 Census, there was a 30 year-old Perthshire man, David Macgill, who was a ‘Railway Agent’ living at 3 Beach St, Stornoway. His two children, ages 1yr & 5months respectively, were both born in Moray so the family must have moved to Lewis sometime after November 1870. Whether his presence was in connection with the Lewis Chemical Works railway or, perhaps, a line that may have been proposed for the Brickworks, a piece about which can be read here: http://direcleit.blogspot.com/2010/05/brick-workers-of-lewis.html , is unknown but appears likely.