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traffic signals sanity checks
UK DfT traffic advisory leaflet (TAL 1/06)
For the design of signalised junctions, the UK Department for Transport's publication (Traffic Advisory Leaflet TAL 1/06)
on General Principles of Traffic Control by Light Signals (DfT 2006)
‘advantages in carrying out a manual preliminary assessment to identify the preferred staging or a limited number of staging arrangements for detailed analysis. The manual method will give a general indication of whether the junction would operate comfortably or close to its capacity limit. This is very valuable in interpreting the output from the software packages and identifying any unrealistic results which would indicate errors in the input data’.
quick preliminary assessments
DfT (ibid) continues and suggest that ‘Before investigating any special staging requirements it is worth checking that the main vehicular flows do not
exceed the overall junction capacity potential… A preliminary assessment can be carried out using the basic concepts of the analysis developed by Webster
and Cobbe ’.
Fast-Answers Quick-Sig is ideal for such preliminary assessment and in fact includes three optional methods for the design of signalised junctions: a design Wizard, the Webster and Cobbe method and a training version (which can be used together with the on-line step-by-step training manual supplied with the software). Although the software includes the Webster Cobbe option, the design Wizard will usually be the fastest way to conduct preliminary assessments for signalised junctions. The Webster Cobbe option gives the experienced user the ability to control the design in detail.