Junction Types and Design
Basic junction form should be determined at the master planning stage. An overview of illustrative junction layouts and principles designing places with junctions can be found in Manual for Streets. The detailed design stage will consider how they are going to work in practice, traffic priority arrangements and the need or otherwise for signs, markings and kerbs.
All junctions should be designed with the needs of pedestrians and cyclists in mind. An Essex Cycle Design portal is currently in development; in the short-term, refer to the Sustrans ‘Handbook for Cycle Friendly Design’ for details of current best practice.
T Junctions
Typically, the side turning is of the major traffic flow, but a T junction that diverts the major traffic flow can be a useful means of reducing speeds.
Islands and Mini-roundabouts
These will be more appropriate for streets of type D and above. The island may be any shape, subject to the minimum dimensions given below. The siting and use of mini-roundabouts for type A and B streets should comply with the Design Manual for Roads and Bridges (DMRB) standards on size and signing.
a. Mountable shoulders in vehicle deterrent paving to provide service vehicle overrun
b. 6.1m radius
c. 7.1 radius
d. Centre section of island - 2m radius
e. Outer edge of island - 1m
Staggered Junctions
These are possible on type E and lower roads within a 20mph zone. The side roads should be staggered by the width of one carriageway, and right/left staggers are preferable to left/right, so as to reduce conflicting movements. Such a junction is possible notwithstanding the junction spacing requirements outlined in the ‘Junction Spacing’ section of this guide.
a. Stagger=carriageway width
b. Right-left stagger reduces conflicting movements
Crossroads
These should only be used in exceptional circumstances and will be treated as special features within a layout (see picture 38).
a. On type 4 and higher category roads these arms may serve no more than 25 dwellings each
b. Main flow of traffic
Non-right Angle Junctions
On type E and lower category roads, non-right angle junctions will be permitted down to a limit of 45 degrees and should accommodate all car-turning movements within the carriageway. Below 80 degrees, overrun spaces for service vehicles become necessary. In such cases, it may be preferable to ban service-vehicle turning movements around the acute angle, provided an alternative route is available and signed in advance.
Page updated: 15/02/2018