Discussion. Trafford Wharf Reconstruction at the Manchester Docks.

Abstract

that one of the most useful parts Jlr. Dcane of the Paper concerned the very interesting tests on piles. He had not seen the results of any tests carried out quite on such lines before, and the information would be of great value for future reference. The Author suggested that it was not within the scope of the Paper to give the result of the consideration of the question of the design of the wharfing itself. He thought the Author had thereby withheld valuable information, because the consideration of a design of that kind must have been of great interest t o those concerned, particularly as it had resulted in a scheme which was, in his experience, unique. The fact that the pre-cast boxes weighed 67 and 62 tons indicated a work of some magnitudewhich was emphasized by the costs given on p. 87. The Author stated that the cost of the heavy part of the wharf was €168 per linear foot, which was equivalent to about E3 per square foot of surface, taking a 57-foot width from the front of the quay to the second row of columns. That figure seemed to be extraordinarily high, particularly when it was realized that every 2s. per square foot represented €10,000 in the capital outlay of the undertaking. The cost was apparently mainly due to the intricate concrete work and the powerful tackle which had had to be used in handling the heavy weights. Had it been necessary to build those boxes up in such a form ? Would it not have been possible to build them 25 feet long, but of less weight, so that they could have been handled much more expeditiously and at considerably less cost ? It was impossible to install heavy lifting-appliances, such as had been used here, without adding very materially to the contractors' cost. The Manchester Ship-Canal apparently had two very effective floating derricks, one capable of lifting 60 tons, and the other 250 tons. It seemed to him that, if the contractors had been given suitable terms for the use of that plant, they would have used it in preference to the 70-ton derrick which was specially constructed. He did not suggest that the work would have been executed as satisfactorily; but, looking at the matter from the point of view of cost, he felt sure that the contractors would have preferred to do the work in the cheapest way possible, provided they could execute it efficiently. In his own experience floating derricks and heavy lifting-appliances held by Port Authorities were generally charged for a t rates which Downloaded by [] on [11/09/16].