TII Publications
DN-GEO-03060
Geometric Design of Junctions (priority junctions, direct accesses, roundabouts, grade
separated and compact grade separated junctions)
April 2017
Page 3
iii.
Cycle Lane: part of the carriageway of a road reserved primarily for use by
cyclists. The cycle lane forms part of the road and it is located within the
contiguous road surface. A cycle lane can also be referred to
as an on-road cycle
track.
iv.
Shared Use Cycle and Pedestrian Facilities: A Cycle Track or Cycleway that is
provided for both cycle and pedestrian use.
v.
Shared roads with Motor Vehicles: A road under low speed/low vehicular traffic
flow conditions that is also provided for both cycle and pedestrian use.
vi.
Greenway: a Cycleway that caters for pedestrian and cyclists in a recreational
environment
vii.
Cycle Network: is a defined collection of routes which
connect key origins and
destinations in a specified area for cyclists.
h)
Downstream: That part of the carriageway(s) where the traffic is flowing away
from the section under consideration.
i)
Dual Carriageway: A divided road with one or more (generally two) lanes in each
direction with carriageway widths of up to 7.5m (for two lanes in each direction i.e.
2 × 3.75m lanes).
j)
Dumb-bell Link Road: A short link road connecting two roundabouts either side of
a dual carriageway or motorway at a grade separated junction (Refer to Chapter
7).
k)
Designer: The organisation responsible for undertaking and/or certifying the
design.
l)
Direct Access: An access that connects directly to a national road including field
accesses and accesses serving one or more properties as described in Chapter 5
national road.
m)
Fork: At an at-grade junction, usually on a link road within a grade separated
interchange, where the road splits into two. Usually both
diverging roads have
equal status and diverge from the single approach at similar angles.
n)
Ghost Island Junction: A junction within which an area is marked on the
carriageway, shaped and located so as to direct traffic movement.
o)
Ghost Island on Merges/Diverges: An area of the carriageway suitably marked
to separate lanes of traffic travelling in the same direction on both merge and
diverge layouts. The purpose of the ghost island at a merge
is to separate the
points of entry of two slip road traffic lanes.
p)
Heavy Goods Vehicle (HGV): Vehicles designed and constructed for the carriage
of goods. Heavy Goods Vehicle refers to vehicle categories N2 (maximum mass
between 3.5 tonnes and 12 tonnes) and N3 (maximum mass exceeding 12 tonne).
q)
Interchange: A grade separated junction that provides free flow of traffic from one
mainline carriageway to another. Refer to DN-GEO-03060.
r)
Interchange Link: A connector road, one or two way, carrying free flowing traffic
within an interchange.
s)
Lane Gain: A layout where a merging connector road becomes a lane or lanes of
the downstream carriageway.
t)
Lane Drop: A layout where a lane or lanes of the upstream carriageway becomes
the diverging connector road.
TII Publications
DN-GEO-03060
Geometric Design of Junctions (priority junctions, direct accesses, roundabouts, grade
separated and compact grade separated junctions)
April 2017
Page 4
u)
Link Road: A connector road separate from the mainline carriageway, which is
used to connect the mainline carriageway to the local road network.
v)
Loop: A connector road, one or two way, which is made up of the elements of the
loops shown in Chapter 7 and which passes through an angle in the range of
approximately 180 to 270 degrees. The loop is considered to extend to the
end of
the near straight length of road contiguous with the back of the diverge or merge
nose.
w)
Low Radius: A radius between the minimum loop radius in Table 8.2 and the Two
Steps below Desirable Minimum Radius with Superelevation of 7% as required by
DN-GEO-03031 for the slip road, link road or interchange link design speed.
x)
Mainline/Major Road: The carriageway carrying the main flow of traffic (generally
traffic passing through a junction or interchange).
y)
Major Interchanges: Interchanges provided at the intersection of motorways, dual
carriageways and national roads to provide free flow for all movements
accommodated. The free flow arrangement removes the conflict points, however
they are generally larger and more complex than the type of junction described in
this standard and must be designed in accordance with DN-GEO-03041 (see
Section 2.6) national road.
z)
Minor road: A minor road is a road which has to give priority to the major road.
aa)
Near Straight: A length of road with a radius no less
than the minimum radii for
the appropriate design speed for straight or nearly straight two lane overtaking
sections for the mainline design speed as outlined in Table 7.1 of DN-GEO-03031.
bb)
Nose: A paved area, approximately triangular in shape, between a connector road
and the mainline at a merge or diverge.
cc)
Non-motorised Users (NMUs): Pedestrians, cyclists and equestrians, including
people with disabilities (see definition of ‘People with Disabilities’) and other
mobility impaired users (e.g. people
with luggage, with children, or pregnant
women).
dd)
Non-physical Segregated Left Turn Lane: A left turn lane from adjacent
roundabout entry and exit, shaped to direct and separate the traffic movement
from the roundabout circulatory carriageway by means of an island delineated
using road markings only.
ee)
Parallel Merge/Diverge: A layout where an auxiliary lane is provided alongside
the mainline carriageway. This term incorporates the auxiliary lane, the nose and
the taper.
ff)
Physical Segregated Left Turn Lane: A left turn lane from a roundabout entry to
the first exit, separated from the roundabout entry, circulatory carriageway and exit
by means of channelised islands (See definition of Channelised Islands).
gg)
Priority Junction: An at grade junction between a
major road and a minor road
whereby the traffic on the minor road must yield to the traffic on the major road.
hh)
Reserved Lane: A lane carrying traffic that is segregated from weaving traffic.
ii)
Road Authority: The authority responsible for the road construction or
improvement scheme.