Bonhams auction 19952 on 4 December 2012 included this lot 283, which sold for £3750.

283 RICH (EDMUND TILLOTSON)

A very good archive representing the military career of Edmund Rich (1874-1937), an officer of the Royal Engineers and surveyor, mostly on the North-West Frontier and in Burma (at first in conjunction with the Survey of India and latterly as one of its directors), also relating to survey in South Persia during World War I, and with the British forces in Southern Russia in 1919, comprising a series of photographs albums, loose photographs, autograph letters, orders, draft reports, maps ephemera, etc., together with a small quantity of photographs, letters and documents relating to Rich’s ancestors, those of his wife Aileen Owen (d.1918), and their son (quantity)

[…]
In 1905 Rich was sent to Peshawar in charge of No. 12 Party with orders to survey the sensitive area north of Kohat Pass. This work lasted four years and included the Bazar Valley and Mohmand campaigns of 1908. The archive contains Rich’s alternative survey for the Kabul River Railway which resulted in the cancellation of the line then under construction, and the dismantling of track and bridges already in place. 1909-1911 were spent in England (Rich married in 1910).
[…]
Source: Bonhams

According to the auction listing, the most substantial of the items include “An album containing titled in manuscript ‘Views of the Khyber Pass…taken chiefly by E.T. Rich when surveying there 1905-1909, approximately 176 gelatin silver prints”.

From this it can be inferred that photos of the Kabul River Railway might well exist.

If you bought this archive, and you happen to read this webpage, is there any chance that I could have a look at it, please? :-)

(a different Edmund Rich was Archbishop of Canterbury in the 13th century, which complicates web searches for any information about this particular one)