The Canadian Northern Railway bridge over the South Nation River
or How Not to Build a Bridge 
Pictures of the
Ottawa Hawkesbury line are almost impossible to find.
No contemporary picture of the bridge has
come to light but this aerial photo, taken when the line was still in
on 14 April 1927, illustrates the bridge and surrounding area. Hawkesbury is to the right (east) while
Some of us, out for a drive in eastern
The CNoR applied for order in council approval on 6 November 1906. The Department of Public Works replied on 4 December 1906.
“The portion of the river which you
intend to cross is
navigable from its mouth to a point about 2,500 ft. above the proposed
bridge. At that place there is a saw
mill and wharves for shipping the products of the mill by barge to
“In order, therefore, to provide sufficient space for the passage of sawlogs etc., upwards to the mill it is suggested that you so amend your plan that the span between piers 3 and 4 over the steamboat channel be increased from 100 ft., as at present proposed, to 150 ft. centre to centre of piers. Will you, in consequence, send me another set of three copies of plan of proposed bridge showing the amendments suggested? On receipt of this amended plan the department will be in a position to make the necessary recommendation to council for its approval.”
The CNoR did not want to provide a 150 foot span, presumably because of the expense, and responded to the Department that “their engineers have reported that a span of 150 ft. in length is, in their opinion, unnecessary at this point, and that at the outside the span should not exceed 120 ft. They claim they have examined carefully all the conditions in respect of the crossing and have satisfied themselves upon this point.” On 9 January 1907 the CNoR submitted three white prints on linen dated January 8, 1907 showing a variation of the crossing by providing for two deck girder spans of 100 ft., three deck girder spans of 90 ft. and one through girder span over the channel of 120 ft. and asked for the order in council as soon as possible.
The application was lost in the
Department but the order in
council was issued on 2 February 1907 (PC 1907-129). The Board of
Commissioners gave its approval on 3 April 1907 (order 2764) and the
was free to begin construction.
Work started on the construction of the piers and abutments but on 22 July 1908 Marine and Fisheries wrote that “complaints have reached the Department that a cement pier built by your company in the South Nation River last year has fallen directly across the channel of navigation and that a serious interruption to the navigation of the river is caused thereby. I have to call upon you to remove the wrecked pier as promptly as possible.”
The CNoR engineer responded;
“I measured the depth of water over the fallen pier last week and there was a minimum of 14 ft. The ordinary depth of channel at low water is from 12 to 15 ft. and as far as I could learn on the spot, the deepest draught boat that goes up the South Nation river draws only 9 feet. The base of the pier does lean a little into the channel, but it is marked by a bush securely fastened to it and does not, I think, offer any menace to navigation.
We will have the obstruction caused by the fallen pier removed at an early date, before low water.”
With further pressure from Marine and
Fisheries, the CNoR
decided to have an independent examination and in September 1908 wrote
C.H. Rust, City Engineer,
“In building the line between
“Before destroying the piers, our Engineering department wishes to have the work examined by competent independent engineers and they have requested our department to apply to you to act in this capacity and to name another independent Engineer, or other qualified person who could be present with you when examination is made.”
On 7 October 1908 Rush provided a
detailed report. 
One of the main piers had fallen over and was completely under water. The other river piers had settled materially out of their original positions: these settlements could be immediately detected by the eye.
He examined the material in the piers themselves. This concrete was built, as is customary, with an outside facing four or five inches in thickness of higher class material and an interior, which is the mass of the pier, of a cheaper mixture. The concrete deposited under water appears to have been of the same quality as that used in the interior of the piers.
The concrete near the water line was simply dissolving away under the action of the water of the river.
He found that the outer, or face concrete, was fairly well mixed, homogeneous in character and able to withstand weathering influences. It varied in quality being better in some piers than in others, but, in general it was so much below the standard usually required for this class of work that he questioned whether the materials were of the proper quality and whether they were used in the proper proportions. He also questioned whether the proper and usual precautions that should be taken when laying concrete in winter, were taken in this case, it was a piece of winter construction. The face concrete was certainly not the cause of the failure of the structure.
The interior concrete was found to be altogether defective and he questioned whether any of it would withstand the action of water. He had no hesitation in describing the interior concrete at the points where he made entry as the worst concrete, if it can be so called, that he ever saw. Much of it was unset and could be readily pried out with a lumberman's peavy and the cement mortar in the mixture was not nearly sufficient to fill the voids between the stones, it being a criterion of good concrete that the mortar must be present in such quantities that it will more than completely fill these voids. There was evidently some reason for economizing in the use of both cement and sand and, in places, he found the so called concrete to consist of nothing but a mixture of stone and clay, the latter being the one common material which should be carefully excluded from concrete. At such points the whole interior was, of course, loose and wet.
It was inevitable that such a mixture would disintegrate under exposure to water and Rush fully approved of the CNoR action in absolutely condemning the concrete masonry in this bridge as unfit for railroad service.
He looked into the west abutment and into two of the river piers with the same result in each case.
This illustrates a general series of problems with the way CNoR engineering projects were contracted and managed. The company would make a deal with a contractor for a section of line. The contractor, in turn, would sub-contract with another group who might very well sub-sub-contract the work and so on. The original price might have been reasonable but, with each sub-contractor taking a cut, the group who wound up with actually doing the work would be squeezed pretty hard with the resulting incentive to cut costs by providing sub-standard materials. This lead to another series of problems in difficulties of supervision and diffused accountability.
It was now time for the government to become involved again. The new plans showed the same bridge structure in the same location but with the piers placed two feet to the west of the original plan. With such a drastic change, a new order in council was required. This was duly passed on 6 November 1908 (PC 1908-2327) and the Board of Railway Commissioners gave its rubber stamp on 21 November 1908 (order 5659).
In the meantime, the Rideau Lumber Company was taking advantage of the situation. It claimed that the bridge and its disruptions were causing them great delays to the extent of $25 per tow. The railway was suspicious that the costs were exaggerated and investigated secretly with knowledgeable rivermen. There was a feeling that the rivermen were dragging their heels and the lumber company was inflating its claims but nothing could be proven.
The first regular train between
Bytown Railway Society, Branchline, June 2008.