PICADY

The PICADY model is now integrated into ARCADY 8 in the form of the Priority Intersection Module. Click here for full details, including pricing, FAQs and a downloadable demo version.

PICADY (Priority Intersection CApacity and DelaY) is a computer program for predicting capacities, queue lengths and delays (both queueing and geometric) at non-signalised major/minor priority junctions. It's an aid in designing new junctions as well as assessing the effects of modifying existing designs.

What PICADY models

• The program can be applied to any three-arm or four-arm priority junction.
• Major roads with either single or dual carriageway may be modelled, including single carriageway with ghost islands or bollards. Minor approaches may have single, flared or two lane approaches. The program can also model one-way roads.
• Signalled and unsignalled pedestrian crossings can be included.
• Accident prediction is available for both rural and urban junction layouts.
• It's ideally suited to model peak periods.
• Queue lengths can be viewed, animated and printed.
• Both drive-on-the-left and drive-on-the-right situations can be catered for.

How PICADY works

• The program reads the geometric parameters of the junction and the traffic flows - the minimum data required for the program to run. Depending on the user's specified requirements, additional data such as geometric delays and accident prediction data is also required in order to carry out extra calculations.
• The geometric parameters and the controlling flows, split into small contiguous time periods, are used to calculate the capacity of each non-priority traffic stream. The queues and delays are then calculated for each time period, i.e. PICADY uses what's known as ‘time-dependent queueing theory'.
• PICADY is an empirically derived model. That is, the principal models it uses are derived from extensive data collection exercises of many existing junctions.
• A comprehensive context-sensitive help system and user guide is provided to ensure users get the most out of facilities PICADY provides.