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quickGreen

Software for Measuring and Calculating Traffic Signal Phase Intergreens

quickGreen is a new innovative software tool to help signal engineers measure and calculate phase intergreens for traffic signal junctions. The software is designed not only to speed up the measurement process but also to reduce errors, improve the ease of checking of intergreens and assist with archiving.

Background

Phase Intergreens are important safety parameters which ensure sufficient clearance times between traffic starting and stopping at a traffic signal junction. They must be determined as part of a junctions design process usually by considering the junctions geometry and the paths taken by different traffic movements. In the UK phase intergreens are measured and calculated using the method described in the Department for Transport's Traffic Advisory Leaflet TAL 1/06. This involves determining conflict points between traffic movements and measuring relative distances traffic movements must travel to reach each conflict point from a scale drawing. TAL 1/06 can then be used to convert this information into intergreen values.

quickGreen assists with the calculation of intergreens by carrying out the repetitive conflict distance measuring work which is time consuming for a person to do but is easy for a computer. As well as speeding up the process of calculating intergreens it also reduces the likelihood of measurement or arithmetic errors, makes it very easy to check the intergreens and provides a convenient way of archiving the intergreens and the process by which they were calculated. Having calculated an intergreen matrix the intergreens can be easily transferred to other software such as LinSig to carry out traffic signal calculations.

Detailed Features

The quickGreen process for determining intergreens is as follows:

A drawing of the junction is imported into quickGreen from any of the usual sources including AutoCAD, a PDF, satellite imagery or even a scanned drawing.
After importing the drawing is calibrated to a known scale within quickGreen.
Lanes, turn paths, and pedestrian crossings are added by overlaying them on the scaled drawing. Turn paths can be easily refined to fit any geometry using typically one or two control points on the path.
As the model is built up, quickGreen will use sophisticated computational geometry to locate conflict points and measure distances between stop lines and conflict points, as required by the calculation method described above. This results in X distances for the critical conflict points.
Signal Phases are added to group lanes controlled by the same phase.
The critical X distances are used to calculate a phase intergreen matrix using the lookup table in TAL 1/06.
Calculated intergreens can be overridden and adjusted if necessary and notes can be added to explain why.
The intergreen matrix can be exported to LinSig or other signal design software.
Traffic - Pedestrian and Pedestrian - Traffic Intergreens can also be calculated.
A detailed PDF report showing how the intergreens were calculated as well as the final intergreens can be produced.

quickGreen can easily accommodate changes to junction geometry. As lanes or turn paths are moved conflict distances and intergreens are instantly recalculated allowing the affects of changes to geometry to be quickly evaluated.

Training

quickGreen is very simple to use and for most engineers who are familiar with TAL 1/06 and how to measure intergreens no in depth training is required. For anyone unfamiliar with how to measure intergreens the subject is covered in our course 'Introduction to Traffic Signals'.