report, however (paragraph 113), we recommend such a sign for use at the junctions of two motorways, and we suggest that this sign should also be erected at other junctions if it should prove necessary.
Junctions of Two Motorways
Advance Direction Signs
102. As with ordinary junctions along the motorway, so with junctions of two motorways it is essential that drivers should receive sufficient warning to enable them to get into the appropriate traffic lane without endangering other traffic. Indeed, this is even more important at junctions of two motorways, because not only will traffic in the offside lane intending to bear left have to move over to the nearside, but traffic in the left-hand lane intending to bear right will have to move out into the centre or right-hand lane. Moreover these junctions cannot be signposted in the same way as ordinary junctions along the motorway because both arms are of equal importance and it is therefore necessary to give the route-numbers and/or destinations of both arms on all the advance direction signs. We propose the provision of a series of three direction signs in advance of each of these junctions.
103. The first advance direction sign (figure 34), like its counterpart for ordinary intermediate junctions, is sited one mile in advance of the junction. The junction symbol is more nearly in the form of a letter 'Y', in order to emphasise that the junction represents a divergence of two equals. For the same reason the route-number of each arm of the junction is given. 104. While we are satisfied that the sign recommended in the previous paragraph will be suitable for most junctions of two motorways, it seems to have given rise to some confusion at the junction on the first section of the London-Yorkshire Motorway (Route M1 ) where the spur to Birmingham (Route M45) branches off to the left. No doubt because of the popular misconception that M1 is the London-Birmingham Motorway, some Birmingham traffic moves over to the right at this point, only to be told at the next sign that Birmingham is to the left. In these rather special circumstances we have prepared an alternative design for this sign (figure 38) which makes it explicit that it is the M45 that leads to Birmingham . It will be seen that it is similar to the final advance direction sign at ordinary junctions along the motorway (paragraph 88 and figure 30), except that ' M1 ' is substituted for the forward destination and the message '1 mile' has been added. We do not consider that the need for this alternative design will survive the extension of the M1 to Yorkshire, when the route-number will become more closely associated in the public mind with more northerly destinations.
105. We recommend that the second advance direction sign should be an overhead sign straddling the whole of one carriageway. We make this recommendation with some reluctance; the sign and its supports would constitute an enormous structure (something fairly elaborate would probably be necessary to facilitate lighting, cleaning and maintenance), and we are fully aware of the disruptive effect that it might have on the landscape. Nevertheless we are convinced that when traffic volumes on the motorway have built up to the maximum expected a sign of this type, which is used in America, Germany, and Italy, will be
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