to the arm representing the motorway ahead by separating it clearly from the border, but in our view improves the design by making it more telling. We do not consider that any difficulty will result from the use of this design at a site where the actual alignment of the motorway may differ from that which the symbol might be taken to suggest.
90. The signs we recommend in this section differ in one or two respects from those erected at Preston in accordance with our provisional recommendations, the most important difference being that at Preston it is the second, not the third, advance direction sign that gives the forward destination of the motorway. When we saw the actual signs in place at Preston we felt that the absence of any indication at the exit, especially at night, of the continuation of the motorway was a defect. We therefore decided to recommend that the two signs should be transposed; besides producing a more logical build-up of information, this device, by deleting 'm' from the old half-mile sign, reduces the height of the tallest sign on the motorway. In the new mile and half-mile signs the stub arm representing the motorway has been lengthened and given a point, and in the half-mile and final signs the route number has been enlarged and aligned with the word-group above it.
Exit Distance Markers
91. We have noted the German use of exit distance markers and consider that they serve a useful purpose. A marker of the kind shown in figure 31 is recommended at distances of 300, 200 and 100 yards in advance of the beginning of the deceleration lane.
92. These signs also differ from those recommended in our interim report, which were in the form of horizontal blue bars on a narrow white triangle. We were unimpressed by the performance of those signs at Preston, partly because they were too small (2 feet 9 inches high with a nine-inch ground clearance), but chiefly because of the presence of blue and white posts of approximately the same size, which were not part of our recommendations, set at 110-yard intervals to mark the outside edge of the hard shoulder. To make the exit distance markers more distinctive we now recommend that they should be rectangular and larger (four feet high with a one-foot ground clearance), that their colour scheme should be reversed and that the bars should be diagonal rather than horizontal. This would make them very much closer to continental practice, although we have not extended the diagonals to the edge of the sign, as in the continental versions we have seen, because we feel that the zigzag effect obtained by cutting them short makes them very much more arresting.
93. In our interim report we also recommended a fourth marker to define the point of land between the slip road and the motorway proper. At our suggestion this marker was omitted at the junctions on the first section of the London-Yorkshire Motorway, chiefly because there was invariably a supplementary exit sign (see paragraphs 94 and 95 below) in the point of land. But experience has shown that some form of marker is desirable in addition to the supplementary exit sign (which because of its width may have to be set some way back from the point), and we now suggest that the point of land should be marked by a bollard, which should preferably be internally illuminated.
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