Modelling of intermittent stages in TRANSYT 16
TRANSYT is an internationally-recognised traffic modelling product used across the globe for a wide range of purposes, including, but not limited to, signal optimisation, corridor modelling, junction design, and traffic impact assessments.
The most recent version – TRANSYT 16 – has expanded on this with the introduction of its ‘Simulation Mode’. This allows TRANSYT to break through the modelling restrictions inherent in previous versions, which assumed that recurring events occur regularly based on signal cycle times, throughout the modelling period. That meant signal stages that were skipped, say, due to a lack of pedestrians at a signalled crossing or the lack of vehicular demand on a particular approach, could not be readily modelled. The best that anyone could do was to observe the situation, record the signal timings, and calculate average stage lengths to reflect the loss of the skipped stages. Of course, this is a simplification of the real world – like all models are – but one that does not translate well into accurate estimations of queue lengths. Thankfully, there is a solution – Simulation in TRANSYT 16:
A stage can be either setup to run every nth cycle or given a probability of running. The latter offering users the option of taking account of the random behaviour of demand-dependent scenarios, as shown below:
This selection will be reflected in the simulation’s Signals Log:
Of course, skipping stages will relinquish time within the cycle, and TRANSYT offers four options as to where that time ends up:
For example, the cycle time can be preserved if that is what is required, by reallocating the time given up by a skipped stage, to the previous or next stages, or split between both:
Of course, TRANSYT 16’s new simulation offers a lot more besides the ability to model intermittent stages, including the modelling of basic VA, or modelling of controllers running on different cycle times. If you have plans to use TRANSYT’s simulation mode in the way described or for modelling something else, then we would be delighted to hear about it, and of course offer our advice in return.
Please do not hesitate to ask our support team via [email protected] for a trial of TRANSYT 16 or to send us your experiences of using the latest TRANSYT 16.