About 1968 much of the Camas Prairie's "downriver" line along the Snake river West of Lewiston ID was relocated when the 4 Snake river dams were constructed.
About 1966 the NP relocated around 10 miles of mainline between Athol ID and Granite ID, eliminating a great deal of curvature, a tunnel, and a large steel trestle.
In 1957 the NP relocated about 17 miles of mainline near Noxon MT as a result of Noxon Rapids dam and the lake formed behind it. They brought challenger 5140 out of storage to operate over the new line to insure that it had settled properly.
More information at these links:
[
finance.groups.yahoo.com]
[
finance.groups.yahoo.com]
In 1956 the MILW did a short line relocation west of Harlowton MT where their mainline crossed the summit of the Belt mountains. This left the Loweth substation some distance away from the tracks which formerly passed right in front. The purpose of this relocation was to reduce grade and curvature.
In 1951 the NP relocated the mainline around the Cabinet Gorge dam near Cabinet ID, approx 5-6 miles.
In the late 1940s or early 1950s the Rock Island did a large line relocation in western Iowa, west of Atlantic. Again for the purpose of reducing curvature and grades.
Bruce Butler