At its northern limit as now constructed the M74 Motorway described in the Paper reaches within 2 miles of the Glasgow city boundary or about 7 miles from the city centre. Considering the semi-urban nature of much of the area traversed, the clearance of property was remarkably low. There were only 14 inhabited dwellings affected in the total length of 14 miles. The price which had to be paid for land and buildings was minimal but not so the cost of the earthworks, as the route which had to be followed traversed the soft alluvial deposits referred to in the Paper for a cumulative length of 63 miles. M r D. D. FraserI would like to mention the flooding problem in the Hamilton Low Parks. With a normal maximum flood of 50 OOO cusecs, the whole area is inundated. Even with much smaller floods of the order of 20 000 cusecs, the extent of flooding approaches quite closely to what is shown here, and a flood of 20 000 cusecs is the type which can be met with in this area on an average of about once every year or two years. It will be seen from this that it was essential that the motorway and the interchange and the slip road had all to be built on embankments to keep the works above flood level. 98. The 10 in. composite base was found to be the most economic for this motorway and, I believe, has proved to be the most economic for motorways in Scotland generally. Bitumen bases have not so far been used to any great extent except in short lengths where speed of construction is important. As far as I know, asphalt bases have not been used at all. This is something which surprises us. 99. Similarly, concrete roads are not popular in Scotland and the length of two miles carried out on this motorway was really a trial length. The Paper records the test results for bituminous surfacing. Now that the whole motorway has been completed, I can show the final results for Stages 1 and 2 in Table 4.100. The method of placing bituminous test results in three categories (in compliance with specification, slightly out, and really unacceptab1e):is well known. It will be seen that the test results on Stage 2 are rather better than they were on Stage 1. This is because a longer period was available for laying surfacing and also, I think, because we were getting to grips with the problem to a greater extent.101. Even so, the percentage of passes falls far short of 100% compliance, but I think it is generally accepted that IOOZ, compliance is an unreasonably high standard to ask for. Indeed, figures of 70, 20 and 10% for the above categories are suggested quite often. The average for all materials on Stage 2 was 66, 28, and 604.
AUTHORS' PRESENTATIONIn introducing a major new item of equipment such as a slip-form paver it was vitally important that its performance and operational characteristics should be evaluated and understood from the outset.139. The design of a satisfactory dowel bar support system had proved elusive for a number of years, although many arrangements had been tried. The Cromwell trials faced up to the problem, which was more acute with slip-form pavers, and the welded assembly with bent stalk feet in its final form had a substantial claim to general adoption as the standard British joint for use with conventional as well as slip-form construction. This would take much of the uncertainty out of present-day construction. 140.There had been a tendency to identify slip-form pavers with large-scale construction and very high outputs, but this overlooked their singular capacity to perform satisfactorily at lower output levels. The Authors believed that there was a much wider field of operation open to these pavers than had hitherto been contemplated, housing estate roads being one example.141. The pooling of resources of design; research and contracting interests at Cromwell in mutual consultation and co-operation throughout the planning and execution of the trials resulted in the development of designs and viable techniques in a remarkably short time, and this form of joint effort led to development in pavement construction which could not occur under normal construction processes.Sir William Glanville (Past-President) said the Authors had been responsible for one of the biggest and most important experiments in mechanized concrete construction which had ever been made in Britain. He had found the Paper particularly valuable because the Authors had described fully the difficulties they had encountered and how they had overcome them, and had pointed out quite frankly that some difficulties still remained.143. The Authors had shown very considerable ingenuity in overcoming difficulties and had demonstrated that with ski11 and intelligent supervision the dip-form paver could be made to work, and work well, both for plain concrete and for reinforced concrete. Sir William had no doubt at all that, given further opportunities for experiment, which he hoped that they would have, the Authors would overcome the remaining difficulties which they mentioned and develop still further the potentialities of the machine. The machine had, of course, a voracious appetite for concrete, and the team operating the machine needed to know not only how to operate it in a general sense but how to deal quickly with the ordinary run of problems, such as changing weather conditions and unexpected variations in aggregates. It seemed to him that it was one thing to operate the machine in the predictable weather of California and quite another to operate it in Britain. What was perhaps even more
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.