Canadian engineer . ven of the piers, where the waterwas deep, the extensions to the existing piers were made insubstantially the same manner. The cribs for these wereclosed in on three sides only and so arranged that the sideswould overlap and fit closely against the old coffendams usedin the original construction of the bridge which had been leftin place. After these joints had been carefully caulked by January i8, 1912. THE CANADIAN ENGINEER 161 divers, and the cofferdam walls puddled with clay, no diffi-culty was experienced in unwatering- with 8-inch centrifugalpumps. Practically all of t
Canadian engineer . ven of the piers, where the waterwas deep, the extensions to the existing piers were made insubstantially the same manner. The cribs for these wereclosed in on three sides only and so arranged that the sideswould overlap and fit closely against the old coffendams usedin the original construction of the bridge which had been leftin place. After these joints had been carefully caulked by January i8, 1912. THE CANADIAN ENGINEER 161 divers, and the cofferdam walls puddled with clay, no diffi-culty was experienced in unwatering- with 8-inch centrifugalpumps. Practically all of the leakage came from open jointsin the old cofferdam. The foundations for the extensions to the seven remain-ing piers, where the depth of water was from 20 to 27 ft.,were carried down to rock by a combined /pneumatic andopen process. In order to reduce the current from 8 to 10miles an hour, to about 2 or 3 an hour at each of the sevenpiers above mentioned, breakwaters were constructed on bothsides of each old Showing Erection of Channel Piers. A derrick boat equipped with grapples and an orangepeel bucket were then used in removing the riprap andboulders to allow the pneumatic caissons to rest on a com-paratively level bottom when they were sunk. The pneumatic caissons were constructed of long leafyellow pine. The walls were heavily cross-braced in theusual manner. A single shaf: with the contractors standardtype of air-lock was used for both men and material. It is customary to build caissons for river work on theshore, launch them in the usual manner, then tow to account of the heavy current at this bridge site, it wasconsidered advisable to build each caisson in place. Accord-ingly, the contractors constructed a pontoon of sufficient sizeto sustain the caisson without drawing more than a few feetof water. As fast as they were required for the work, thecaissons were constructed in this pontoon and anchored withsteel cables to existing piers. The temporary
Size: 1631px × 1531px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublishertoron, bookyear1893
