Tourism was on the increase in the area, and there were ambitious ideas that imported goods traffic at Oban would be routed to the eastern Scotland towns and cities over the line.
As well as the ordinary commercial traffic of the districts served, tourism became a significant seasonal source of income, and the attractive scenery became the focus of great interest.
However the remaining gap of 15 miles (22 km) between Comrie and Lochearnhead proved an attraction to those who proposed railways, and a number of ideas that foresaw extraordinary business potential if the Callander and Oban line were connected to Crieff: transatlantic goods traffic would, it was claimed, be landed at Oban and conveyed to the eastern side of Scotland over such a line.
[1] Considerable attention was given to the environmental impact of the line through high amenity landscape: a parliamentary committee considered the matter.
Finally on 15 June 1904 an inspection train was run from St Fillans to Lochearnhead, and the line opened for public passenger traffic on 1 July 1904.
It was a considerable distance from the settlement after which it was named; in fact the line passed closer to Lochearnhead but high above it on the hillside, and remote from any public road.
It was announced that the final link would open on 1 May 1905, and an inaugural train from Aberdeen to Oban was planned, reflecting the continuing hope that a new east-west traffic would be generated.
[note 1][1][2] The junction station at Balquhidder was relocated about 170 yards (155 m) west of its former location; it was provided with 800 feet (244 m) long platforms.
The rise of motor buses accelerated the loss of passenger business, and on 1 October 1951 the line closed between Balquhidder and Comrie.
However the track remained in situ until 1959 as the line was used sporadically throughout the 1950s to transport materials to the Glen Lednock hydro-electric schemes under construction in the area.
In 2001, the Kendrum viaduct was refurbished in connection with improvements to the cycle path, including the replacement of a missing steel span over the river.
Some of the shorter and moderate span bridges were constructed with in-situ concrete, then popular as a building material in the remoter areas.