to compile cyclic traffic flow profiles for each junction in the network being
examined. These profiles are utilised to compute the best possible set of signal
timings for all signals in the network area.
5.6 Concluding remarks,
Within the design process for an at-grade intersection, whether it is a priority
junction, roundabout or signalised junction, the same basic design procedure is
employed. Firstly the traffic data must be collected, indicating the proposed
loading on the junction during peak times. Data on the physical characteristics
of the site must also be available, in particular horizontal and vertical align-
ments in the vicinity. Design standards may then dictate what type of intersec-
tion is employed. The design of the junction itself will be an iterative process,
where layouts may be altered based on operating, cost and environmental
concerns.
The design of grade separated intersections is not detailed within this text.
See O’Flaherty (1997) for details of this intersection type.
5.7 References,
Binning, J.C. (1999) OSCADY 4 – User Guide(Application Guide 25). Transport and
Road Research Laboratory, Crowthorne, UK.
Burrow, I.J. (1987) OSCADY – A computer program to model capacities, queues and delays
at isolated traffic signal junctions. TRRL Report RR105. Transport and Road Research
Laboratory, Crowthorne, UK.
DoT (1981) Junctions and Accesses: Determination of Size of Roundabouts and
Major/Minor Junctions. Departmental Advice Note TA 23/81.Design Manual for
Roads and Bridges, Volume 6: Road Geometry. The Stationery Office, London, UK.
DoT (1985) Traffic flows and carriageway width assessments. Departmental Standard
TD 20/85.Design Manual for Roads and Bridges, Volume 5: Assessment and Prepara-
tion of Road Schemes. The Stationery Office, London, UK.
DoT (1993) The geometric design of roundabouts. Departmental Standard TD 16/93. The
Stationery Office, London, UK.
DoT (1995) Geometric Design of Major/Minor Priority Junctions, Departmental Stan-
dard TD 42/95.Design Manual for Roads and Bridges, Volume 6: Road Geometry. The
Stationery Office, London, UK.
DoT (1996) Traffic Appraisal Manual. Design Manual for Roads and Bridges, Volume 12:
Traffic Appraisal of Road Schemes. The Stationery Office, London, UK.
Hunt, P.B., Robertson, D.I. & Bretherton, R.D. (1981) SCOOT – A traffic responsive
method of coordinating signals.Laboratory Report LR 1014. Transport and Road
Research Laboratory, Crowthorne, UK.
Kimber, R.M. (1980) The traffic capacity of roundabouts. TRRL Report LR942. Trans-
port and Road Research Laboratory, Crowthorne, UK.
The Design of Highway Intersections 151