TRANSYT
| Developer(s) | Transport Research Laboratory |
|---|---|
| Stable release | 14.1.0 / December 2011 |
| Operating system | Windows (XP, Vista, 7) |
| Type | Traffic Software |
| License | Software license agreement |
| Website | http://www.trlsoftware.co.uk/TRANSYT |
TRANSYT is a software package developed in the UK by the Transport Research Laboratory. TRANSYT is the acronym for TRAffic Network StudY Tool. It is used to assess and optimise the performance of networks of road junctions by assigning costs to vehicle stops and delays. This allows modelling of everything from individual junctions to 200 node networks, including unsignalled, partially signal-controlled or fully signal-controlled roundabouts.
Contents |
[edit] (Brief) History
Investigations carried out in the UK into possible improvements in traffic control of urban networks in the 1960s[1] resulted in the development of TRANSYT/1 in 1967 by the Transport Research Laboratory (TRL). Two trials of TRANSYT were carried out – one in Glasgow and another smaller one in West London. The full-scale Glasgow trials were carried out with the cooperation of the City Council in Glasgow. TRANSYT signal timings went ‘live’ in May 1967. TRANSYT was shown to reduce the average journey times through the network of signals in Glasgow by about 16 per cent. A similar reduction was recorded in the other smaller trial in London. Because of TRANSYT’s international appropriateness TRANSYT is now one of the most widely used signal timing programs in the world.
TRANSYT has continued to be developed by TRL ever since its first release.
[edit] Summary of Capabilities
Modelling of existing conditions and future conditions
Modelling of mixed signalled and unsignalled networks
Evaluation of time-varying traffic conditions
singal timing optimisation using a choice of three optimisers
Offset and split optimisation
phase and stage sequence optimisation
modelling of indirect traffic control effects
traffic steam-by traffic stream (lane-by-lane) analysis
Account taken of platoon dispersion and blocking-back effects
Modeling of flared junctions, storage in front of stopline and other complex junctions
Flexibility to model novel designs due to TRANSYT's building-block nature
Choice of units and driving-side
[edit] Data Requirements
Data input in Transyt involves:
- dividing roads and lanes into either links with shared signals and shared traffic movements; or using TRANSYT 14's ability to specify lanes and traffic streams;
- further dividing flows from different sources within a single section of roadspace using either shared links or letting the inherent ability of traffic streams to do this for you, in order to maintain the traffic arrival platoons.
- assigning a saturation flow to each link (or lane), indicating the maximum flow of traffic over the stop line during the green time;
- entering the signal timings that apply to each link (or traffic stream).
[edit] Results
Output includes:
For each link or traffic stream:
- a performance index (indicating the cost of the stoppages and delays on that link)
- the maximum capacity
- the degree of saturation
- the average maximum 'back of queue' length during the cycle
- the average queue length at the end of red
- practical reserve capacity (PRC)[2]
- uniform, random and oversaturated delay
- animated uniform queues
- wasted green time
- WebTag-based fuel consumption
- various graphical outputs including time-distance diagrams and cyclic flow graphs
For the network overall:
- Performance Index (indicating the cost of the stoppages and delays within the network)
- total distance travelled
- mean journey speed
- fuel consumption
TRANSYT can also optimise signal timings over the network to find the combination with the lowest Performance Index. It does this using a choice of techniques - a hill-climb algorithm hill climb, a shot-gun hill-climb (which takes longer but is likely to lead to better results) and Simulated Annealing. The hill-climb algorithm looks for the lowest performance index and holds the signal timings that give the lowest performance index, only updating the timings if a more efficient set of timings has been found.
[edit] Current Release
TRANSYT 14's capabilities have been extensively extended to cover the modelling of wholly unsignalled junctions (Roundabouts, T-junctions, etc.) within signalised networks. TRANSYT 14 also includes the ability to model blocking back effects and platoon dispersion effects within the same network, which is particularly useful for the modelling and evaluation of all types of signalised roundabout, and any other network that contains a mix of long stretches of road, and short stretches of road that are prone to blocking back. This is performed using a combination of a Cell Transmission Model (CTM) and a Platoon Dispersion Model (PDM).
Summary of new features:
Modelling:
Blocking back and platoon dispersion modelled in the same network
User Equilibrium Assignment of traffic flows
Lane Balancing of traffic flows on network entries
Traffic Stream and Lane network representation
Mutual opposition modelling
RR67[3] saturation flow estimation per lane
Optimisation:
Alternative optimisers (Hill-climb, Shotgun-hillclimb and Simulated Anealing)
Sophisticated OSCADY-style stage and phase optimisation
Phase and stage minimums and maximums
Too high and too low degree of saturation penalties
Modes of Operation:
Fully featured student edition
Leased version
Advanced/Basic mode of operation
Standalone and Network versions within same installation package
Graphical Interface:
File comparison tool and PDF or Word format reports
New and enhanced graphs
Multiple network Views (acting also as multiple print areas)
Data File Library (Template) system with graphical preview screen
Default windows layout (defined via a new Window Manager)
Docking system for multiple window layouts
Easier manipulation of signal data
SCOOT and SCATS traffic flow import
auto-mirroring of files for drive-on-the-right
Junctions:
Fully unsignalised junction modelling
Priority junction objects calculate give-way coefficients from geometric data*
Modelling of indirect traffic control effects at give-ways
Incorporates TRL's latest ARCADY[4] and PICADY[5] equations
- Requires active ARCADY 7 and/or PICADY 5 licence
International Features:
Drive on the left and drive on the right capability
Automatic mirroring of template files and instant re-orientation of networks
Alternative phase/stage/signal-group terminology
Auto-generated phases/stages/signal-group ID's can be numbers or letters
Many rules-of-the-road can be catered for
[edit] References
- ^ HILLIER J A (1965) Glasgow experiment in Area Traffic Control. Traffic Engineering and Control, Vol.7, No.8 (Dec), pp 502-509, and Vol.7, No.9 (Jan 1966), pp 569-571
- ^ WEBSTER and COBBE (1966). Traffic Signals. Ministry of Transport. Road Research Technical Paper No.56. London. HM Stationary Office.
- ^ KIMBER R M, M McDONALD and N B HOUNSELL (1986). The prediction of saturation flow from road junctions controlled by traffic signals. Department of Transport, TRRL Report RR67, Crowthorne: Transport and Road Research Laboratory
- ^ KIMBER R M (1980). The traffic capacity of roundabouts. Department of the Environment Department of Transport, TRRL Report LR 942. Crowthorne: Transport and Road Research Laboratory.
- ^ KIMBER R M and R D Coombe (1980). The traffic capacity of major/minor priority junctions. Department of the Environment Department of Transport, TRRL Report SR 582. Crowthorne: Transport and Road Research Laboratory.
[edit] External links
TRANSYT Product Page: [1]
