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T.P.D-M.V.2.4
4.5.4 Dpuble Roundabouts
4*5.4*1 As mentioned in paragraph 4.5*2.2, where a junction has more
than four entries, a double roundabout may be preferable to a
normal roundabout. In such a situation a double roundabout
achieves better capacity with acceptable safety characteristics
in conjunction with a more efficient use of space. Other
situations where double roundabouts can be particularly useful
include :
(a) The improvement to an existing staggered junction
where it avoids the need to realign one of the
approach roads thereby achieving a considerable saving
in construction costs;
(b) At unusual or a symmetrical junctions, such as
scissors junctions, where the installation of a single
island roundabout would require extensive realignment
of the approaches or excessive land take (see Diagram
No. 4*5.4.1);
(c) At the joining of two parallel routes separated by a
feature such as a river or railway line;
(d) At existing crossroads where it is desirable to
separate opposing right turning movements allowing
them to pass nearside to nearside (see Diagram No*
4.5.4.1); and
(e) At overloaded single roundabouts where, by reducing
the circulating flow past critical entries, it
increases capacity*
4*5.4.2 Where the double roundabout is comprised of, mini roundabouts
they should only be used where all the approaches are subject to
a 50 km/h speed limit.