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T.P.D.M. V.2.3
(Al/2001)
3.11.7 Minimum Carriageway Width
3.11.7.1 As the roads serve as an Emergency Access for fire engines a minimum carriageway width
of 3.5m should be provided.
3.11.7.2 Suitable widening should be provided on bends though it has been found that, due to
sightline constraints, a two lane carriageway will often be required.
3.11.7.3 At passing bays, lay-bys and elsewhere where a two lane section of road is required a
nominal carriageway width of 6.0m should be provided, with appropriate widening on bends
as shown in 3.11.7.6.
3.11.7.4 At junctions with other roads the carriageway should be widened to at least 6.0 m. The
length and width of the widened section must be sufficient to allow the largest likely
vehicles to manoeuvre safely and this assumed vehicle length should not be less than 12m.
In particular at a junction with a more major road, traffic turning right from the major road
should not be obstructed by traffic waiting to exit from the minor road.
3.11.7.5 A planning reserve should be provided to allow for future widening of the carriageway to at
least 6m (with appropriate widening on bends), and the need for an even wider carriageway
must be considered. In addition allowance should be made for additional footpaths and any
engineering support works.
3.11.7.6 Table 3.11.7.1 is an indication of appropriate widths on straights and bends:
Table 3.11.7.1
Widths on Straights and Bends
Inner Radius Single Lane Two Lane
Straight 3.5m 6.0m
150m 3.5m 6.0m
100m 3.8m- 6.3m
75m 4.0m 6.5m
50m 4.3m 6.9m
40m 4.5m 7.2m
30m 4.8m 7.8m
25m 5.1m 8.2m
20m 5.4m 8.7m
15m 5.9m 9.6m
10m 6.6m (8.0) 10.9m
5m 8.0m (10.0) 13.5m
Om 9.0m (14.0) 16.5m
(-) The figures in brackets are the widths required for long wheelbase vehicles.