

1855.] 



ON THE ACTION OF THE ICE UPON THE BRIDGE AT RICE LAKE. 



2-19 



TORONTO, JUNE, 1855. 



On the Action of the Ice upon the Bridge at Rice Lake. 



By T. C. Clarke, C.E. 

 (Communicated to the Canadian Institute, April 'Zlit, 1855. 

 The bridge of the Cobourg and Peterboro' Railway over the 

 Rice Lake, in the county of Northumberland, is perhaps the 

 largest Railway bridge on this continent, and one of the largest 

 in the world, — its total length being a trifle over two miles and 

 a half. The Railway crosses from the Cobourg shore to Tic 

 Island by a pile bridge of 3,754 feet in length. Here it 

 curves a little, the deflection being 2i°. From Tic Island to 

 the north side of the main channel, a distance of 2,760 feet, 

 there is a succession of wooden cribs 10' X 20' in size, sunk 

 eighty feet from centres, filled with stone, and carrying a su- 

 perstructure of that class of bridges known as " Burr's Truss." 

 In the channel, there is a pivot draw on a turntable, sup- 

 ported by a pier 20'X'IO' in size, and giving two openings of 

 fifty feet each. The bridge raised on an incline from each end 

 towards the draw, and the spans immediately nest it, give a 

 clear headway of twelve feet, to afibrd a passage for the cabins 

 built upon the rafts which come down the Lake. 



From the end of the truss bridge to the Indian village shore, 

 a distance of 6,728 feet, is a pile bridge, similar to the other, 

 except that it is strengthened every five hundred feet by a crib 

 10'X20' in size, loaded with stone. The cross section of Rice 

 Lake accompanying this paper, shows these dimensions of the 

 bridge. 



The bottom of Rice Lake is black mud, in a semi-liquid 

 state, and capable of affording no support to piles. This some- 

 times reaches neai-ly to the top of the water, and sometimes 

 there is a depth of ten to fifteen feet of water before reaching 

 it. It affords nutriment to the wild rice (Zizania aquatica. L.), 

 from which the Lake takes its name, and which grows in large 

 patches in such luxuriance that it is difficult to paddle a canoe 

 through it. Under this black mud there is a stratum of very 

 hard and compact sand, overlaying the clay. 



The depth of water and mud averaged from the low water 

 level, shown in the section, is about fourteen feet south of Tic 

 Island, and sixteen feet between the Truss bridge and the Indian 

 shore. The total lise and foil of the Lake is six and a half feet. 

 The piles are driven through the .sand and a little into the 

 clay, in some instances ; generally, however, they are driven an 

 average of ten feet into the sand, which was a difficult pro- 

 cess ; the pile not going more than two inches at a blow, from 

 rams weighing 18 cwt., falling through forty feet leaders, after 

 it had begun to penetrate this sand. 



It will be observed that from Tic Island to the channel, 

 where was evidently the ancient bed of the river, it is deeper 

 than the rest of the l^ake, being an average of twenty-eight 

 feet from low water mark. In the channel it is thirtj'-six feet 

 from low water mark, and forty-two and a half feet from high 

 water mark to the hard bottom. This depth rendered an ordi- 

 nary pile bridge impracticable, and accordingly the truss bridge, 

 resting ou crib piers, as before mentimied, was designed to 

 carry the Railway over this part of the Lake. 



The mode of construction was as follows : — Four long piles 

 were driven and capped, to bear the vertical pressure of the 

 bridge until the cribs could sink to their bearings. They also 

 Vol. TTL, No. 11. June. 1855. 



served as guides for the cribs, which were built around them, 

 10'X20' in size at top, and battening 2" in 12" at the ends, 

 and 1" in 12" at the sides. They were made of square timber 

 above, and round below water. They were sunk to their 

 • places through the ice in winter, and then loaded with bowl- 

 ders, collected along the shores. 



The construction of the pile bridge will be seen from in- 

 spection of the accompanying drawings. The piles, of which 

 the centre pair were white oak, the outside pair and the spur 

 piles in .some cases pine or tamarae, were driven, and capped 

 with pine caps 12x12. The spur piles were driven with a 

 leaning machine, so that their tops stood about four feet from 

 the others. They were then drawn up by strong tackle, and 

 secured with 1" round bolts. The corbels are fastened to the 

 caps and piles by 1" square rag bolts three and a half feet 

 long. They are notched an inch on the caps. The stringers 

 of pine, 12" X 18", are secured to the corbels by 1" round 

 screw bolts. Ties of 3" oak plank connect the stringers toge- 

 ther on top. 



The quantities of materials in this bridge are as follows : 

 184,000 lineal feet of piling. 

 138,000 " " round timber in cribs. 



644,000 feet B. M. square " " 



1,932,000 " " " " in bridge. 



250,000 lbs. iron in bridge. 

 20,000 yards stone in cribs. 



The total cost of the bridge has been not far from 8175,000. 



It remains now to describe the effect which the ice has al- 

 ready had upon this stracture, and to consider what are its fu- 

 ture prospects of stability and permanency. 



It was predicted by many persons, previous to commencing 

 this undertaking, that no structure could possibly be built 

 which could res'ist the power of the ice in Rice Lake, — which 

 forms to the thickness of two and a half feet; expands with 

 such force as to " buckle" up into high ridges, from the heat 

 of the noonday sun ; and contracting again in the cold nights, 

 cracks and splits with a noise like that of artillery, and with a 

 tremendous power which, as they declared, no artificial struc- 

 ture could resist. Moreover, they said, after the ice has 

 "taken," the lake rises some two or three feet, and the ice, 

 being frozen to the piles, must inevitably drag them all out. 



To these evil forebodings it was replied that it was not sup- 

 posed that a pile bridge could sustain the thrust of the ice for 

 any length of time ; it might be disturbed and thrown out of 

 line and level, but notwithstanding it could serve to carry the 

 trains across the lake until such time as it could be filled up 

 with a solid embankment. It was not expected that it would 

 last for ever ; but if it lasted long enough to form a means 

 of communication across the Lake until it was filled up from 

 dirt waggons, that would be a great advantage, — sufiiciently 

 important to justify the cost of the bridge. To be .sure, if the 

 Company had plenty of time, and unlimited means, it would 

 be better to fill the Lake up as they went along, leaving only a 

 passage for the waters ; but, in their circumstances, this was 

 entirely impossible, for it would have required such a large im- 

 mediate outlay, with so remote a prospect of remuneration, 

 that the project would have been killed. 



The bridge was accordingly built, and the result has thus far 

 justified the anticipations of its projeotors ; while, on the other 

 hand, the prognostications of those who feared danger from the 

 ice have bcen'partially realized. The bridge has been much 

 twisted and shaken, but although ita stmightness and regularity 

 have been destroyed, it still stands in its place, i'uUy cqua' to 

 the ta.sk of carrving unusually heavy engines over in .'•aftty. 



