Discussion. Extension of Ballard Pier, Bombay.

Abstract

The Ballard Pier extension was constructed at the same time as the Bombay Dock expansion scheme, which was started in 1964 and finished around 1970.58. Possibly the most interesting part of the Paper is that concerned with the design and construction of the quay. Although there are certain standard approaches to the design of quays, the optimum solution for a given set of conditions may not be easy to find. Horizontal loading differs considerably from one quay to another, and with the introduction of containers vertical loading has considerably increased in the last few years. Quay heights also vary greatly, not only to accommodate different vessel sizes but also to take account of tidal ranges. Other factors affecting the design are the condition and level of the sea bed and the exposure of the berth, but the most important one is undoubtedly the soil properties, both of the foundations and of the back-up material. The question as to whether the quay is to be constructed under water or in the dry has to be decided and the use of monoliths, caissons, cofferdams, cylinders, sheet piles and suspended deck construction must all be considered. 59. The design described in the Paper, which involves a method of construction which has not been frequently used, might be developed with advantage for other locations besides Bombay. The idea of a buttress wall with arches from buttress to buttress has seldom been adopted in recent quay design, which is surprising in view of its many advantages: a block work wall or a mass concrete quay built in a cofferdam would have entailed much more concrete and in consequence would have been considerably more expensive. The method adopted requires little heavy plant, an important point when the length of quay is limited and its cost cannot be spread over a long length of wall.60. The customs hall roof was originally designed to be of self-supporting aluminium curved segments which would have made a very economical form of construction. Unfortunately, the Indian aluminium companies refused to roll curved segments, and conventional trusses had to be substituted.61. The Architects for the central concourse and customs sheds were Mathew Ryan and Partners. Their names should be added to the Acknowledgements in the Paper. Mr D. Jones, Chief Engineer, British Transport Docks BoardThe Paper makes little reference to the additional trade needed to justify the extension of Ballard Pier, and perhaps the Authors can give some information on this point. In particular I should like to know whether the revenue from such additional trade was regarded as being sufficient to support the investment, or whether there is an element of subsidy in the investment in the facilities of the Port of Bombay.63. I was very interested in comparing the design of the dock walls with that in the extension of the Alexandra Dock (now Indira Dock), described in earlier papers.1*2