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].

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In 8 35 of the Paper, filling between the hinge face plate and the hinge casting was referred to. This was provided because it was very difficult to fasten the hinge accurately to a concrete wall. The face plate was put in place first: A gap of about t. in. was left between the two and then gritted epoxy resin was poured down between them to fill the gap. We were rather afraid of doing this without some experimental testing, so we had a test rig built in the laboratory. It was about half the size of the actual job, and we tremmied the epoxy resin into this set-up through very thin pipes. We had some Perspex windows in the face shutter to see how it behaved, and to our satisfaction the gap filled up perfectly. 56.The rail bedding referred to in 8 36 was done with a similar mixture and proved extremely effective; we examined the bedding 12 months or so after it had been in service and it appeared to be absolutely sound, with no signs of cracking up or deterioration of any sort.57. The radial arms were fabricated allowing for a nominal gap of 1 in. at each end, and after site welding and adjustment of the walings the gaps at the hinge end were carefully measured and packings were machined to fit, tapered where necessary. It was found impracticable to repeat this procedure at the waling end owing to lack of flatness of the waling flanges, and the gaps were filled with an epoxy resin grout similar to that used between the hinges and face plates. The bolts holding the radial arms to the hinges and walings, together with the bolts in the other major connexions, were tensioned to predetermined loads to prevent opening of the joints under live load conditions. 58.In 8 48 brief mention is made of troubles which have occurred with the bogie wheel bearings. These troubles have been the subject of considerable investigation and re-design and modifications to the bogies are now in hand. The original design is illustrated in Fig. 4 of the Paper. The design loading was compounded from the vertical load and a transverse frictional force at rail level limited by the 12.5% coefficient of friction of the articulation pin bearing bush. It was considered that any transverse tracking forces between wheel and rail could be neglected owing to the conical geometry adopted. The resulting maximum pressure on the Railko bearing material, taking into account the flexure of the shaft and the compressibility of the bearing material, gave a factor of safety of three on the ultimate compressive strength of the Railko.59. It is estimated that the sector gates were operated about 2000 sequences during assembly, commissioning and in service, but in October 1972, rough and erratic running of the east gate was noticed and the gates were withdrawn from service. The bogies were removed and returned to the Contractor's works for dismantling and examination.60. Of the total of eight bearings, in five the Railko material had disinegrated and the shafts worn to a depth of 10 mm in places. The remaining bearings were in fair condition but with some signs...

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