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.
It was quite clear in the Glasgow studies that the free use of the motor car to the city centre would be consistent neither with the financial resources that were available for the construction of new roads, nor with the nature of the centre itself. We therefore allowed for restriction on car usage throughout the study. We have recommended that travel by car to the city centre should be regulated through the control of parking by the city. This method is capable of fairly immediate application.Further it could work in tandem with more sophisticated pricing mechanisms when and if these become available. A second point which we should like to stress is the close inter-relation between the renewal and redevelopment of the city and the urban roads programme. This inter-relation calls for close co-operation between a wide variety of disciplines from the earliest stages of the scheme. One very important aspect of this co-operation is the need to examine in some depth land uses adjacent to the motorway. On the question of system planning, we believe that above a certain size of city, and particularly if there is a strong commercial centre, it is difficult to postulate an urban motorway system which will not require a road surrounding the centre both to serve it and to act as the focus of the motorway system. Whether or not this i s known as an inner ring is irrelevant to the problem. The next point concerns the depth of design studies, where we believe that a plan should be specific and should deal with the lines of the roads in some detail, despite the uncertainties inherent in a long term road programme. M r CullenWe believe the decision to develop a system of primary roads to motorway standards on alignments separate from existing arterial roads has proved to be the right one. In the only two instances where high capacity routes have been proposed along the line of an existing arterial road there have been increasing difficulties at every stage as the plans have been developed. 87.The staging of the construction of the motorway system and the building of individual contracts so as to cause the least feasible disturbance should be considered at the earliest stages in preliminary design. The possibility of minimizing the cost of the first part of a staged interchange should also be considered at the early design stage.88. It is of interest that the first target stage for the motorway system, 1975, produces assigned traffic volumes on the motorways then built generally similar to those which they will ultimately carry. This tends to support the decision to build the full cross section as each stage of the system is built. It is also interesting that the traffic assignment to the 1975 system shows relief to existing roads well away from the new motorways.89. We believe that the geometric design standards adopted for urban motorways, especially near the central area, should be flexible. Probably the most practical way of achieving this flexibility is to have three values for each design standard: a normal minimum, a desi...
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