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4.6.6 Visibility
4.6.6*1 Visibility distances are related to the design speed of the road
as shown in Table 4,6*6.1*
Table 4.6.6.1
Visibility Distances at Grade Separated Interchanges
Design Speed Desirable Minimum Absolute Minimum
(km/h) (m) (m)
120 300 225
100 225 165
85 165 125
70 125 95
60 95 70
50 70 50
40 50 40
30 40 30
4*6*6.2 Forward visibility at the merge or diverge should be similar to
that on the mainline, but once on the link road the visibility
standards applicable to that route apply,
4.6*6.3 Sideways visibility is particularly important at the merge
section and this is provided by a long merge nose which is shown
on the merging layouts as 60m, which should be considered as
minimum*
4.6.6*4 The minimum length of diverge nose is 40m. The vertical
alignment of the diverge link beyond the nose should be readily
visible to traffic in the diverging lane so that drivers can
assess the speed value in advance.