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Chapter 10. Geometric design issues and the development of computing practice so as to affect policy

Volume 1 Part 4
Brief résumé of Chapter 10:
Geometric design issues and the development of computing practice so as to affect policy

W.E. Gallagher BSc, CEng, MICE, MIHT
formerly Director, London Regional Office
previously Head of Highways Computing
and Director Transport, South West Region, Department of Transport

The preceding two chapters of this Volume having described the contributions to the creation of Britain's motorways made respectively, at the planning stages, by maps and, when the plans came to be set out on the land, by surveying, this Chapter has much design process to fill in. Here Bill Gallagher's special mathematical and design skills reveal themselves alongside his vision of the tasks encountered in his Civil Service career. He faced the practical need to turn plans safely and economically into reality. He also faced the task of appraising what geometrical form was best suited to a motorway's location and how its safe and swift functioning would be accommodated.

Location follows partly from the geography and geology affecting the motorway's alignment (as chapter 3 of Volume II shows) and partly from its function. Function can be defined as the adequate provision, for national, regional and local economic and social reasons, of access for fast-moving vehicles carrying people or freight while maximising safety and efficiency and minimising detriment to the environment.

To secure the appropriate and safe interaction between driver, vehicle and the motorway structure, that structure has to be given geometrical shape in dimensions which will safely and efficiently accommodate driver and vehicle at the intended speeds. To devise and standardise dimensions for this purpose in differing geographical situations constitutes a field of mathematical problems which, when solved, have been found to entail an administrative requirement that allows the designer of a defined section of motorway a degree of discretion in their application.

The formulation and application of standard dimensions for Britain's motorways would coincide with the development of information technology which, while accelerating the processes of producing any individual plan, has also added progressively both the requirement for skilled design of software programs and the opportunity to prepare many versions of plans for comparison in administrative or public contexts. The increasing capacity to do this has in turn had manifold consequences for the way routeing decisions were taken - a long process encompassing a succession of changes which in turn offers further insights into the range of technical and environmental endeavour necessary to improve highway design practice during the twentieth century. Confluence of this stream of technological change with the effort required, in circumstances which were changing also in other ways, to create the national motorway system itself in the space of a single working lifetime has magnified the total effort of intellect, resourcefulness and devotion required and delivered.

This chapter like the next, supplemented by chapter 3 of Volume II, trace the theory and practice of determining highway geometry during the period of active motorway construction and the effects on policy of its development and eventual computerisation. This subject, which was unusually well published in technical journals, covers surveying, the design of horizontal and vertical alignments, setting out, cross sections, earthworks, calculating the volumes and the haulage of spoil, geometric and aesthetic design standards and the layout of junctions for safety.

Many of the papers mentioned here emanate from Planning, Transport, Research and Computation Ltd's (PTRC) seminars and conferences. The organisation itself came into being in the mid sixties as the brainchild of a number of enthusiasts from the London University Computer Centre who organised seminars relating to planning and transport, with special emphasis on the developing computer applications. The seminars drew attendance from all sides of the industry, including the universities and research establishments. They also attracted participants from European countries and further afield. In 1973 the seminars were brought together into a multi-stream Summer Annual Meeting and this format has been retained ever since. While formal PTRC proceedings may be examined in their offices in Hammersmith, fresh insight was derived by assembling much that had never been seen within that perspective before, alongside data provided by others, using papers published in the Journal of the Institution of Highways and Transportation (IHT) - here cited just as "Highway Engineers" - which are available from the library of that Institution. The Library of the Institution of Civil Engineers (ICE) contains copies of all its own papers and those of the Institution of Municipal Engineers for these two Institutions amalgamated in 1984. It also contains copies of all IHT papers, most of the publications of the Roads Research Laboratory, now known as the Transport Research Laboratory (TRL), and copies of recent papers produced by PTRC and nearly all of the significant Memoranda published by the Transport Department.

The main source of departmental documents is, of course, the PRO. The Laboratory retains its own, kept alongside a vast specialist library. Nonetheless, some of the technical memoranda proved difficult to locate. Although the Highways Agency provided a full list of memoranda published since 1968 they were unable to produce a list of earlier titles - and neither the Agency nor the Department itself was initially able to locate copies of all the documents identified within that post-1968 listing. Eventually, a complete set of memoranda, stretching back to early post war years, was tracked down in the Environment Department of Gloucestershire County Council where the Director, Peter Bungard, subsequently arranged for all the Transport Departments' technical memoranda on design which are no longer current to be accessible in the Gloucestershire Record Centre.