Download SCOOT USER GUIDE

SCOOT USER GUIDE
666/HF/16940/000
change in the considered range, exit concurrent modelling with Control-E, change the
STOC and re-enter concurrent modelling with Control-E.
5.11
Troubleshooting
There are several problems that can arise during validation. Recognising the cause is
part of the "SCOOT art".
5.11.1
There may be large discrepancies in the flow arriving. This could be due to:
a) incorrect journey time
b) vehicles joining or leaving the link between the detector and the stop line
c) a fault in the detector
d) the wrong detector has been connected
e) you are looking at the wrong link and have not checked your M14 message
properly.
5.11.2
If the flow is correct but the clear times are erratic this may be due to:
a) incorrect start lags
b) incorrect end lags
c) journey time
d) the junction has a fault and has dropped off computer control. This happens
more often than one might imagine.
e) observer not concentrating
5.12
Network Validation (Fine Tuning)
This section deals with the analysis of the operation of SCOOT after link validation in
a region has been completed and the resolution of problems that may subsequently
occur. Network validation must be carried out before SCOOT is left on line full time
and will normally take about 30% of the total commissioning time.
It is important that the traffic engineer does not jump to conclusions when trying to
assess the cause of a problem. Always spend some time observing the problem before
making a change and even then only change one parameter at a time. There is a great
temptation when trying to resolve problems to alter the saturation occupancy to
achieve more green time on a link when the problem may well be a defective detector
or that the saturation occupancy on another link is too low thereby wasting green time.
5.12.1
Node Fine Tuning Display (NFTD)
Whilst fine tuning extensive use should be made of this display. All links on a node
are displayed. When a link is green a "+" is displayed next to the link letter. If exit
blocking is occurring then a "-" is displayed next to the link letter. If the link is faulty
the link letter will be shown in inverse video and if historic flow profiles from
666_HF_16940_000.doc
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