"From the collection of my ancestor (possibly the one sitting on rail along with the boy), who was a pharmacist and travelled extensively around the world" -- Ivor Rackham. Date and location unknown. Photograph scanned and restored by Ivor Rackham).
There is no clear identification of the locomotive or location or date. From discussions on the PR mailing list, this is possibly NWR (formerly Punjab Railway) No. 31, listed by Hugh Hughes in "Indian Locomotives" as a 2-4-0 tender locomotive built by Neilson in 1861. If so, this locomotive existed as No. 31 until 1879 when it was renumbered into the combined stock of the Scinde Punjab and Delhi Railway - or may have ended up as a contractor's locomotive. Photograph suggests hot and dry climate; the turrets were also more common in northwestern British India.The river is not identified, nor the works, whether repair of track destroyed by flash flood or other event, or alternatively could be all new construction. Possibilities include the Kaiserin-i-Hind (Empress of India) bridge under construction, or the Kotri Bridge, or a part of the Lansdowne Bridge, or even a different, (perhaps currently non-existent) bridge such as for the Nari river crossing near Sibi.