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T*P*D.M.V.2.4
4.6.9*7 The design flows in v.p.h., adjusted as above, should then be
plotted on Diagram No* 4.6.9*1 to identify the appropriate flow
region, indicated alphabetically*
4.6.9.8 Using Table 4.6.9*1 the appropriate types of layout, suitable
for handling the flow region assessed as above, are identified.
The diverging lane types indicated by an asterisk are likely to
prove the most acceptable in terms of level of service. Where
flow combinations are close to boundaries between different flow
regions, the layout types indicated for the adjacent flow region
should also be considered.
Table 4.6.9*1
Type of Diverging Layout Appropriate to Flow Region
Diverging Lane Type
1
2 3 4
5 6
7 8
9
Number ( Upstream Main Line
of ( Link
Lanes ( Downstream Main Line
2
1
2
2 3 3
2 1 2
2 3 2
3 4
2 2
3 3
3 4
1 1
2 3
4
2
2
( P
( Q
( a
Flow ( S
Begion { T
( U
( V
«
* ft
ft
ft
ft *
«
*
ft
« «
»
«
*
*
ft
ft
ft
f
ft
ft
4.6.9-9 The diverging lane types are shown in Diagram Nos. 4.6.9.2, 3, 4
and 5* In conjunction with Table 4.6.9*1 the following notes on
each layout type should be considered in deciding upon the most
appropriate layout.
4.6.9*10 Types 1 * 3 (Diagram Ko. 4.6.9.2)
The direct diverging lane is the most economical layout for
single lane links and is appropriate up to flows of
approximately 1000 v.p.h. after correction and where site
conditions are favourable. Where the diverge is situated on a
right hand curve, or where the intersection is on a gradient,
the parallel diverging lane layout is more appropriate.