20
Incidents during operation
In accordance with Highways Agency specifications, the Evo
master controller and all associated signal heads monitor
themselves continually for faults or unexpected incidents during
operation. The system as a whole adheres to a defined set of
responses for particular failures, as discussed here.
Red vehicle/pedestrian signal failures
Red vehicle signal failure in Vehicle plus Ped or Ped-only setups:
• If ALL red vehicle signals fail on an approach*, then the
signals on all approaches will immediately return to
ALL RED
for 50 seconds, after which all signals will extinguish and the
controller will stop operation.
On the master controller, the text display will show
Stopped
and the mimic indicators representing the failed red signals
will flash. See
Resetting the system
Red vehicle signal failure in Vehicle-only setups:
• If ALL red vehicle signals fail on an approach*, then the
green signals on all other approaches/phases will be
suppressed. In other words, as any other phase begins its
sequence, the green signal that should immediately follow
the red/amber will be blanked. The signal head with the
failed red is the only one that will continue to show green
during its active cycle. The green times for all phases will be
reduced to 12 seconds.
• If more than one approach has a total red signal failure,
all the signal heads will immediately return to
ALL RED
for
50 seconds, after which all signals will extinguish and the
controller will stop operation.
On the master controller, the text display will show
Stopped
and the mimic indicators representing the failed red signals
will flash. See
Resetting the system
Red pedestrian signal failure:
• If any single red man signal has a failure this is treated as
a total approach fail. The signals on all approaches will
immediately return to
ALL RED
for 50 seconds, after which all
signals will extinguish and the controller will stop operation.
On the master controller, the text display will show
Stopped
and the mimic indicators representing the failed red signals
will flash. See
Resetting the system
Green vehicle signal conflicts
When the operation mode is either Vehicle or Fixed Time:
• If opposing phases show green signals simultaneously at any
time, then the signals on all approaches will immediately
return to
ALL RED
for 50 seconds, after which all signals will
extinguish and the controller will stop operation.
On the master controller, the text display will show
Stopped
and the mimic indicators representing the failed green
signals will flash. See
Resetting the system
When the operation mode is either Hold All Red or Manual:
• If opposing phases show green signals simultaneously at any
time, then all signals immediately change to red (no amber
signal) and will remain at red. See
Resetting the system
on
*
When phase linking is used, the duplication of signal heads
facing in the same direction permits a slight relaxation of
the above rules. Where 2, 3 or 4 signal heads are facing the
same approach, the master controller will maintain normal
operation until the last remaining head ceases normal
operation, whereupon the above procedures will occur.
