Critical-Path Method Outlined By Engineer

Press, Volume CI, Issue 29872, 12 July 1962, Page 13

Critical-Path Method Outlined By Engineer

The critical-path method, which is revolutdonising construction in the United States, was described to the Canterbury branch of the New Zealand Institution of Engineers last evening by Mr F. P. S. Lu. a senior lecturer in civil engineering at the University of Canterbury. He studied the method this year in America as winner of the W. A. Stevenson award of the institution. “The critical-path method is a new and powerful tool for construction planning.” Mr Lu said. "It has been developed in the United States since 1956 by the United States Navy to accelerate its Polaris missile programme. Other organisations have used it to ensure the completion of vital engineering projects. The major computer producers have developed standard programmes for application of the method. . . . Particularly it is suited to the construction industry. Stanford University and the Massachusetts Institute of Technology are offering courses on the method. "Fundamental Concept” The fundamental concept was that some operations in construction were critical and must be carried out before the project could progress but that other operations were non-critical and a certain amount of delay was permissible without affecting the over-all schedules.

Mr Lu said. The primary aim of the new method was to pin-point every critical operation and, at the same time, compute the maximum leeway, or “float” allowable. Mr Lu said a “do-it-your-self” worker at home could, with profit, examine the application of the method to laying a concrete path. Stages were: Approving the project, setting out the plan, excavating, laying the forms, concreting, curing, stripping and cleaning up. Some of these were vital; some could be spread; some could overlap. On a big construction project determination of the critical path could make an enormous improvement in efficiency and economy, Mr Lu said. He described every stage. Among the advantages listed were:— (1) The critical path compelled the planner to think more deeply and searchingly and better appreciate sequence, inter-relationship, and inter-dependence. The master chart was invaluable for control purposes, training personnel, and transferring information if management changed. (2) Optimum timing could be obtained for all operations, and this permitted maximum co-ordination. (3> Most operations (up to 90 per cent.) were noncritical and contained some ‘•float.” Detecting these was invaluable in levelling off the use of manpower and equipment. (4) “Management by exception” was possible because, when critical operations were defined, directors could concentrate on these. Saving In Cost The method had an enormous potential in more economical costing, Mr Lu said, but computers were needed for maximum benefit. Research, development, and construction could proceed hand in hand in some cases There were fascinating opportunities where a firm had several projects at the same time, which could be worked into an over-ell schedule by the method. It could also be used in factory management and the launching of new products. “I believe the critical-path method will be of great benefit to industry in this country,” said Mr Lu. “I hope that some firms will be sufficiently impressed to try it ... A useful approach is to try it on smaller projects first to get the feel of the method without getting bogged down in detail. Adjustments can always be made later.