Ghost island junctions: Usually a T-junction or staggered junction within
which an area is marked on the carriageway, shaped and located so as to
direct traffic movement (see Fig. 5.3).
The Design of Highway Intersections 107Figure 5.3Ghost island junction.
Figure 5.4Single lane dualling.
The type or level of junction utilised depends on the flows from both the major
and minor roads. The ‘simple’ layout is appropriate for new junctions in rural
locations where the 2-way AADT on the minor road is not expected to exceed
300 vehicles with the major road 2-way AADT not exceeding 13 000 vehicles.
For single carriageway roads, the different levels of T-junctions appropriate to
a range of flow combinations are illustrated in Figure 5.5 (DoT, 1981). The
information takes into account geometric and traffic delays, entry and turning
capacities and accident costs.
Single lane dualling: Usually a T-junction or staggered junction within which
central reservation islands are shaped and located so as to direct traffic move-
ment (see Fig. 5.4).