Supplementary Exit Signs
94. An enlarged version of the sign illustrated in figure 8 or 9 of Appendix IV is recommended for use at the exit, sited on the right of, and indicating, the slip road. We do not consider, however, that the lettering here needs to be so large as that in the advance direction signs, and the height of the lower case lettering may therefore be reduced from 12 inches to 10 inches in this sign.
95. At many of the junctions along the first section of the London-Yorkshire Motorway the slip road leaves the motorway at such a narrow angle that there is not room between them for signs of the type recommended in the previous paragraph if they are to be large enough to be read from the point at which the driver should begin to turn off. We recommend that in these circumstances a rectangular sign should be employed which embodies only the route-number and a left- pointing arrow (figure 32); the driver will receive confirmation as to placenames almost immediately from the advance direction sign on the slip road (paragraph 97 below). The route-number is in 20-inch characters. (At present, in accordance with an earlier recommendation from us, these junctions are provided with a shortened version of the sign illustrated in figure 8 of Appendix IV which includes no place-names. Experience has shown, however, that the fact that the route-number virtually fills the sign reduces the blue background both in area and in the intensity of the colour and consequently reduces the target value of the sign . In so squat a sign the pointed end is also comparatively ineffective. The sign we now recommend has a larger area of undiluted blue background and is, we believe, more emphatic.)
Carriageway Markings
96. We have not in general interpreted our terms of reference as embracing carriageway markings, but we feel we should draw attention here to certain difficulties, which both we and the police have noticed, in determining the exact position of the exit slip road, especially at night. These difficulties may be partly due to a contrast in colour between motorway and slip road, producing an inhibiting effect on drivers intending to leave the motorway, and this inhibiting effect may be enhanced by the very wide broken white line separating the deceleration lane and slip road from the motorway-the object of which is, of course, to prevent drivers entering the slip road by mistake. We believe that the improved target value of the supplementary exit sign we recommend in the previous paragraph, and the illuminated bollard recommended in paragraph 93, will go some way towards overcoming the difficulties, but we recommend that consideration should also be given to the possibility of using catseyes to make the position of the slip road more clear at night or in fog, although care will have to be taken to ensure that in fog the catseyes do not lead all the motorway traffic into the slip road. It may be that the only really satisfactory solution of the night-time difficulty will be to light the whole junction.
Final Advance Direction Sign on the Slip Road
97. For the final advance direction sign required on the slip road to indicate to traffic leaving the motorway the direction to be taken on joining the all-purpose road we recommend the use of a sign similar to that illustrated in figure 6 of Appendix IV. The x-height of the lettering should be not less than four inches.
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