[2] The military and strategic concerns for securing the border with Afghanistan were such that, Francis Langford O'Callaghan (who was posted from the state railways as engineer-in-chief) was called upon for a number of demanding railway projects, surveys and constructions in the Northwest Frontier.

[3] What initially started off as military and strategic railway project, ended up becoming part of the North Western State Railway network upon its formation in 1886.

[4] The Khojak Tunnel opened in 1891 and the railway reached Chaman near the Afghan border.

[8] In 1906 a steam motor coach from Vulcan Foundry was purchased.

[9] By 1936, the rolling stock had increased to 1332 locomotives, 18 railcars, 1,494 coaches and more than 30,000 freight wagons.