UTC System Handbook - Siemens

System Handbook for an STC UTC System 666/HE/16940/000
7.13.6 Intersection permanent demand checking:
If a demand dependent stage runs during every cycle for a 60 minute period it is
deemed to have a permanent demand and a permanent demand fault will be
raised.
If permanent demand checking is set to monitor all stages of an intersection and
that intersection is under local control and the stage has appeared every cycle and
every time has run for the maximum time configured in the UTC data base then a
permanent demand fault will be raised.
7.14 Controller Checks
7.14.1 Introduction
The Controller Checks facility allows either all intersection controllers connected
to the System to be checked on a regular basis, or individual controllers to be
checked at operator request.
7.14.2 Timing of checks
Regular checking is accomplished by entering the Controller Checks command in
the System timetable for each day, or one or more days in the week or month,
depending on the frequency of checking required. It is usual to schedule this
command for a time of day when the road network is lightly loaded, typically, in
the early hours of the morning. Up to 6 (B) controllers connected to each TCC
may be being checked at the same time. Controllers previously isolated by a fault
are not checked. Fixed time plan or SCOOT control are temporarily suspended
whilst checking is in progress.
Checking of controllers stops automatically when all controllers connected to the
System have been tested or when the stop time is reached. This stop time is
identified by placing a Controller Checks stop command in the timetable, usually
at the time when the road network is likely to become busy again. Testing of the
current controller is always completed before termination. Any controllers not
tested when the stop time is reached are checked when Controller Checks is next
run from the timetable. It is always advisable to put the cancel Controller Checks
command in the timetable to occur well before normal traffic flows start.
7.14.3 Interruption by higher priority
If during controller checks a higher priority mode of control is called on a
junction or junctions then controller checks are suspended on that equipment.
When all the other junctions have been checked then controller checks should
return to these junctions and try a second time. Should it be impossible to
complete the checks then a message is output.
Higher modes of control can be:
a) hurry call
b) green wave
c) manual wave
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