CNR South Thompson Bridge - Kamloops, BC
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T0SHEA
N 50° 40.787 W 120° 20.072
10U E 688305 N 5617606
This is one of two Canadian National Bridges at Kamloops, this one crossing the South Thompson River, the other crossing the North Thompson.
Waymark Code: WMMAKD
Location: British Columbia, Canada
Date Posted: 08/22/2014
Views: 2
This bridge was completed in 1926, replacing a temporary bridge across the South Thompson, built over the river in 1918. It was built as a swing bridge as the river was still a commerce route at that time.
The bridge, other than the swing section, is comprised of steel girder sections resting on concrete piers. Its total length is about 250 metres (825 feet), while the length of the swing span is only about 60 metres (208 feet).
In recent times the swing span was used regularly, allowing the Wanda Sue paddlewheeler, a tour boat, to pass on its tours of the South Thompson. These tours ended in 2005.
Most recently the swing span was opened in early July of 2011 to allow a private boat to pass. With the era of commercial traffic on the river long gone, the only boats plying the waters today are small private craft which pass easily under the bridge except in times of extremely high water.
Coordinates given are at a good vantage point, where there is a large parking lot and walking trails along the river.
On the branch to downtown Kamloops, three bridges have been built over the South Thompson River at the same location. The first structure was the temporary wooden trestle erected in 1913 to move construction supplies between the CPR and CNoR yards. The last two bridges were more durable. A swing span was involved in each of these bridges. The first permanent structure went into use in 1919 and was a wooden truss bridge with a central swing span. It was intended to be used for a short period. In 1927 it was replaced with a steel girder bridge which has a 208 foot swing span of through truss design. This span rotates on a circular pier of 25 foot diameter and provides two openings, each of 90 foot width. It was built by Coughlin Steel Ltd, a Vancouver firm that fabricates steel which built merchant ships during World War I.
When the freshet occurs each year in late spring, the water level of the South Thompson River in flood usually is less than 5 feet from the bottom of the girder spans of this bridge.
The bridge was designed to be swung manually, with an arrangement somewhat akin to winding a mantlepiece clock. A four sided stem or shaft rises vertically to track level and presumably a capstan bar was attached to this and two or four men rotated it. Nowadays a compressor is trundled onto the swing span and creates the turning power. Curiously, there is no signal interlocking system in place to warn of the open span. As speed is restricted and the bridge is within yard limits presumably it was felt this safeguard was unnecessary. No passenger train ran over this bridge from 1963 until 1988 when the thrice-weekly summer train, the "Rocky Mountaineer", started running.
From Canadian Rail, page 169