Developer(s) Transport Research Laboratory
Stable release 1.3.1 / June 2011
Operating system Windows (XP, Vista, 7)
Type Traffic Software
License Software license agreement
Website http://www.trlsoftware.co.uk/OSCADYPRO

OSCADY is a software package developed in the UK by the Transport Research Laboratory. The more recent phase-based version of the software is developed by Transport Research Laboratory in collaboration with UCL. OSCADY PRO is the acronym for Optimised Signal Capacity And DelaY: Phase-based Rapid Optimisation. It is a computer program for optimising phase-based signal timings and calculating capacities, queue lengths and delays (both queueing and geometric) for isolated traffic signal controlled junctions.


(Brief) History

The original stage-based OSCADY[1] was first produced for the personal computer in 1984.

The English language version of the phased-based version of OSCADY (OSCADY PRO) was first released in 2006.

A Japanese language version of OSCADY PRO was released in 2009.

Summary of Capabilities

OSCADY PRO is a tool for traffic signal engineers to help in the design of signal-controlled junctions that use either mixed phase and stage-based traffic signal controllers or pure phase-based ones. Phase timings are optimised by the program to give the best possible junction performance, subject to various criteria, such as safety and user-imposed constraints. As part of the optimisation process, OSCADY PRO will automatically generate and optimise stages and stage sequences.

Since OSCADY PRO only analyses single isolated junctions, it is very simple to use and quick to run. To model networks of all types of junctions (signalised, partially-signalised and unsignalled), an alternative related software package (containing similar technology and techniques) can be employed called TRANSYT.

How it works

OSCADY PRO is ideally suited to modelling traffic demand that varies over time, such as over a morning or evening peak period. A time-dependant method of predicting queues and delays[2] is used. The method considers the probability od queue lengths as a function of time.

When run, OSCADY PRO finds signal settings that are optimal for the given pattern of traffic according to the following criteria: (which are reported individuallly)

a. critical cycle time
b. maximum practical capacity and
c. minimum delay


Average rate of delay
Queue lengths
PRC (Practical Reserve Capacity)[3]
Effective green time
Degree of saturation
Final queue at end of green
Final queue at end of red
Geometric delay
Accident predictions
Phase Delays
Stage sequence
Phase sequence
Optimal phase timings

Current Release

OSCADY PRO 1.3.1 is the latest released version. In additon to its existing features, this version contains a new option to generate a deliberately-simple set of stage sequences as an alternative to its default optimal ones.

International Features:
Drive on the left and drive on the right capability
Alternative phase/stage/signal-group terminology
Japanese version


  1. ^ BURROW I J (1987). OSCADY: A computer program to model capacities, queues and delays at isolated traffic signal junctions. Department of Transport, TRRL Report RR105, Crowthorne: Transport and Road Research Laboratory.
  2. ^ KIMBER, R M and ERICA M HOLLIS (1979). Traffic queues and delays at road junctions. Department of the Environment and Department of Transport, TRRL Report LR909. Crowthorne: Transport and Road Research Laboratory
  3. ^ WEBSTER and COBBE (1966). Traffic Signals. Ministry of Transport. Road Research Technical Paper No.56. London. HM Stationary Office.

Further reading

  • Summary OSCADY PRO User Guide[1]
  • An (independent) appraisal of OSCADY PRO[2]

External links

OSCADY PRO Product Page: [3]

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