From Koti, the train climbs 5,020 feet to enter Barog Tunnel (tunnel no-34). Constructed over a period of three years, between 1900 and 1903, this 3,752-feet long tunnel that crosses the Punchmunda ridge about 900 feet below, is the longest narrow gauge tunnel in the world today. An interesting feature of KSR is the multi-arched stone bridges that resemble Roman aqueducts. Out of a total 869 bridges that cover 3 per cent of the line, only two are steel girder bridges. One of the most photographed multi-arched bridge is bridge no-541, popularly known as Kanoh Viaduct. Constructed in 1898, this 52.9 metre-long bridge has 34 arches. After Kandaghat the train again climbs uphill to Shoghi at 6,010 feet. From Shoghi, one can get great views of the Chail Valley. Banished from Shimla by the British, Maharaja Bhupinder Singh of Patiala established his own hill station of Chail. After this, the train stops at Taradevi station. The famous temple of Taradevi is a short distance away. Past Taradevi, the train goes under Prospect Hill through Taradevi tunnel (No-91) to Jutogh, winding its way to take a pause at Summer Hill station.

In the final lap of the journey the train passes through the 1,135-feet long Inverarm tunnel (No-103) to arrive at Shimla station. Built in 1903, this station has been accorded a heritage status by the Indian Railways. In 2008, UNESCO conferred world heritage status to KSR.
— VIKAS SINGH, RAIL ENTHUSIAST
Courtesy National Rail Museum