Strictly speaking, it is not possible to do this since the definition of queuing delay has an element of geometric delay in it. The element of overlap is the delay associated with drivers checking that it is safe to enter a junction. It can be argued that this delay is both an element of queueing delay AND geometric delay and hence ARCADY is in fact correct to show it the way it does, included in both. Clearly this does not help those wishing to obtain a combined figure for total delay. However, It should be noted that, if the geometric delay was to be re-defined in ARCADY and PICADY to exclude this overlap it would then not be possible to measure the queueing delay as is currently possible! I would suggest that anyone facing a request for a total value of delay should provide both the queueing and geometric delay tables separately with an explanation of the fact that there is an overlap. Alternatively there is an approximate representation of driver checking time given in TRL Supplementary Report SR810, although at the time of writing this, I have not sourced the origins of this ‘estimate’ of driver checking time and so cannot comment further on its usefulness. Furthermore, the size of the overlap (the ‘checking delay’) will tend to relatively small in comparison with the queueing delay.
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