TII Publications
DN-GEO-03060
Geometric Design of Junctions (priority junctions, direct accesses, roundabouts, grade
separated and compact grade separated junctions)
April 2017
Page 39
5.5
Direct Accesses
The overriding principle is that direct vehicular access onto national roads shall be avoided as far as
practicable.
Where direct vehicular access onto national roads cannot be avoided, it shall be provided such that
the visibility envelope from the access does not overlap with the visibility envelope from any other
access/junction. Should an overlap occur, a local road connecting both accesses shall be provided
with a single direct access onto the national road.
5.5.1
Existing Direct Access
Where an existing national road is to be improved on-line, there are likely to be existing accesses.
Where possible these accesses should be relocated to connect to an existing regional or local road
and accesses combined as described above. Where this is not practicable, the layout of the access
onto the new road should be designed in accordance with the geometric standards for a new or altered
access described in the following sections.
Any such layout which does not achieve the geometric standards for a new or altered access shall
require a Departure from Standard.
Any application which results in a material increase in the volume of traffic or a material change in the
type of traffic entering or leaving a national road shall be carefully considered. Generally, a material
increase is considered to be if the turning traffic flows would increase by 5% or more, although there
may be cases when it is important to consider smaller increases.
5.5.2
Geometric Layouts of Small Direct Accesses
Table 5.3 gives a number of basic direct access layout types and their associated approximate levels
of use. Three layouts are proposed for the following circumstances on single carriageway roads.
a)
Layout 1: Field access
b)
Layout 2: Access to dwellings
c)
Layout 3: Left in/Left out
These are illustrated in Figures 5.10, 5.11 and 5.12. All other direct accesses shall be designed as a
priority junction in accordance with this Standard. Field accesses and accesses to dwellings are
regarded as a Departure from Standard on Dual Carriageway Roads.
Table 5.3: Recommended Standard Access layouts
Field Access
Access to Dwellings
Left in/Left Out
Direct
Access Layout
1
2
3
Traffic using the access
AADT
Less than 10
movements a week
Less than 150
movements a week
Less than 150
movements a week
Layout suitable for
carriageway
configuration
Single
1
Single
Single & Dual
1
May be used on Dual Carriageways where maintenance access to attenuation ponds and pollution control areas are taken directly off
the mainline.
Note: These figures are recommendations and indicate the approximate level at which alternatives for connections should be considered.
Designers should look carefully at the safety implications involved in providing the alternative connection.
TII Publications
DN-GEO-03060
Geometric Design of Junctions (priority junctions, direct accesses, roundabouts, grade
separated and compact grade separated junctions)
April 2017
Page 41
Figure 5.12: Direct Access Layout 3
–
Left In/Left Out
5.5.3
Entrance Gates Across Direct Access
Entrance gates across a direct access shall be set back to accommodate one vehicle in the access,
clear of the main running lane and preferably clear of the footway/cycle facility. The vehicle to be
accommodated should be of the largest type to use the access on a regular basis, (which
in the case
of agricultural vehicles may include a trailer). Wherever possible, gates should open away from the
road and where this is not possible; the set-back should be increased to allow for the gates to open
unimpeded.
5.5.4
Non-Motorised Users at Direct Accesses
In rural situations a cycle facility will need to cross direct accesses such as farm and house entrances.
As a general objective the priority at these crossings should lie with the cyclists and it is preferable
that the alignment of the cycle facility is retained through and past the access.
Visibility requirements for motorised vehicles at direct accesses shall be in accordance with
requirements set out in this document and the ‘x’ distance shall be measured from the n
earside edge
of the carriageway without the need to accommodate the cycle facility.
Additionally, the access will require
a visibility envelope
setback of 2.0 m (‘x’ distance) from the cycle
facility with a stopping sight distance based on the design speed of the cycle facility as set out in Table
5.7.
There will be situations where the cycle facility may need to bend in or bend out to accommodate the
private entrance. The provision of a bend in cycle facility at a private entrance is best suited to one-
way cycle tracks, however it can be applied to a two-way cycle tracks subject to the provision of an
absolute minimum 0.5 m carriageway separation distance Figure 5.13 demonstrates a bend in
crossing associated with a direct access on the public road.
The provision of a bend out cycle facility requires sufficient set back to allow a single vehicle to wait
between the main carriageway and the cycle crossing point. This distance will be based on the
maximum size of the vehicle using the direct entrance and shall be 5.0 metres if the direct entrance
serves a private house and 15.0 metres if serving a farm entrance. Figure 5.14 demonstrates a bend
out crossing associated with a direct entrance on the public road.