|November 1975, Vol. 1, No. 1||Rail and Transit (Toronto)||Page 5|
Back in 1953
.. Let's drop a bridge in here, and ..
That's right! You may have observed railwayhookslifting a large girder bridge into place on piece at a time, but have you ever witnessed one being dropped into place? This is not a method of bridge-building commonly practised, or even recommended for large structures, but it has occurred on the Canadian National. One such incident took place on the Fergus sub at Drayton Ontario, approximately ten miles south of Palmerston, Ontario, during the winter of 1952-1953.
At this location, the railway line crosses the Conestoga River and adjacent flood plain on a span of approximately 170 feet long. Prior to 1953, the tracks utilized an under-framed wood trestle for the river crossing, along with an earth fill of several hundred feet in length that extended over the flood plain. This steel structure, erected around 1905, was deemed quite suitable for the trains of the day, and would certainly last for a lengthy period of time. However, as time progressed, the trains using this line gradually became longer and heavier. As well, immediately off the northern end of bridge, the line commences a relatively short but rather stiff climb past the (now razed) station and through a double curve north of town. This grade, extending for approximately one-fifth of a mile, posed no serious threat for most trains passing to the north in the early years of the century, as there was a lengthy from the southern end that afforded engineers ample opportunity toget up a good runfor the grade and curves north of the bridge.
As stated, trains became longer and heavier during the 1920's and 1930's. Because of this, it was necessary to place a speed restriction over the trestle. This effectively robbed engineers of their chance to increase speed for the upcoming grade. As well, trains that were heading north that had to stop at Drayton station were sometimes unable to develop enough power to begin the climb up the grade from a standing stop. This necessitated a reverse movement back over the bridge to enable the locomotive to attain a gradient that would allow forward movement . The cure for this dilemma was found inDoubleheadingmany of the trains. This certainly provided enough motive power to pull the trains up the grade, but greatly increased the stresses being applied to an aging bridge.
By the last 1940s the speed restriction over the bridge had been lowered to ten miles per hour because of the advancing age and deteriorating condition of the span, and by 1952 it was quite obvious that a replacement span would have to be built if the line was to remain open.
The bridge chosen as a replacement was a steel girder trestle that had been built in 1948 by Canadian Bridge for export to China, to be used near Kowloon. However, as the Communist regime took over control of China's political affairs in 1949, the bridge was never shipped, but placed in storage.
In 1952, the bridge was sent, disassembled, to the erection site at Daryton. As traffic demands on the line were rather heavy, orders were given that the bridge was to be installed with a minimum of interruption to the traffic flow. Accordingly, it was decided to drop the bridge, fully assembled, into place.
With the old bridge still in service, work commenced during the winter of 1952 on the erection of the new bridge. The old abutments, still quite solid, were strengthened and also lengthened approximately six feet on either side. Cribbings were then erected around the abutments, filled with rocks, and then packed with cement that was pumped in around the rocks under high pressure. In order to enable the cement to set properly in the cold weather, a portable steam generator was parked on a siding at the station, and a heavily-wrapped steam line run down to the construction area. By wrapping the cribbings and pumped steam around them, temperatures were kept at a proper level to permit the cement to harden properly.
South of the old span, a spot beside the right-of-way graded level to enable assembly of the new structure. The new bridge was thus completely assembled on the ground a few yards from its final destination. Up to this point, no interruption of train service had occurred.
Sunday, April 19, 1953, was the day chosen to suspend train operations to allow the bridge to be put into place. Twohooksand a work train showed up early in the morning to begin operations that were to last only one day. The plan was to drag the newly assembled bridge up onto the tracks of the right-of-way, then slide it along the tracks until it was directly above the old span and block into place. Then the old span would be severed at both ends and lowered into the river; the blocks removed from the new span, and the twohookswoulddropthe new span into place. Necessary track connections would be quickly made, and the bridge opened to traffic.
On paper, the plan looked terrific. In actual fact, things occurred even more speedily than anticipated. In order to enable the new span to slide easily over the old one, the rails were greased. Onhookproceed across the river over the old span, then pulled the new span down the greased rails onto the old span. There it was blocked into place. It was at this point that operations proceeded more quickly than planned. The intention was for the twohooksto lower the old span to the river bed one end at a time. However, no sooner had the first crane begun lowering its end when the hook straightened out, thereby allowing the one end of the span to drop freely into the river below. The sudden shift of weight onto the hook at the other end was too much at once, and it also straightened, allowing the other end of the bridge to fall. Thus what was scheduled to occupy the better part of an hour was completed within a few seconds. The rest of the erection was completed without mishap, and trains were passing over the new span within a day. The old bridge was then cut into pieces on the river bank, loaded onto cars and hauled away for scrap.
The new span saw a diminishing frequency of service through the 1950s and 1960s, remained unused completely from the fall of 1970 to the summer of 1971. Today the span is still far from beingoverworked, having a minimum of four trains per week pass over it, and maximum of approximately a dozen. Most of these trains are extra cattle trains, operated in the late fall, that head northwards loaded with from three to thirty cars of cattle, and return southbound empty. These certainly provide no strains in terms of tonnage.
The other trains to use the span are the unit oil trains, on their way from Toronto to Douglas Point. These trains, loaded on the northward trip, weight from 4,700 tons to 7,000 tons, plus weight of the locomotives. This weight, were it applied frequently, would perhaps shorten the life expectancy of the span. However, as this weight occurs only twice per week on the average, it is reasonable to assume that the bridge, that was dropped into place originally, will be around for many years to come.
Canadian National work crews are busy replacing the old bridge across the Conestoga River on 19 April 1953.
The new bridge is in place in this view, the old bridge over the Conestoga River has been dropped into the river. Canada National H-6-c class locomotive 1321, hard at work here on 19 April 1953, was built by Montréal Locomotive Works in 1910. The locomotive was later renumbered 1530 and finally scrapped in April of 1960.