Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 10 Page 90 of 265
The timing range is 0 to 255 seconds in 1-second steps and there is one time for
each phase. If no blackout/flashing green is required the timer should be set to 0
seconds.
6.5.5 Red Amber Time (RAT)
The red/amber ‘gaining right of way’ step for traffic phases is fixed at 2 seconds of
red/amber for all UK controllers.
However, the ‘gaining right of way’ step for traffic phases can be configured
differently for non UK controllers. For example, it can be removed altogether so the
phase moves directly from red to green, or the red/amber time can be altered.
The timing range is 0 to 255 seconds in 1-second steps (although all inter-green
times to this phase must be the same or longer than this time period). There is one
time for each phase.
6.5.6 Leaving Amber Time (LAT)
The ‘leaving right of way’ step for traffic phases is fixed at 3 seconds for all UK
controllers.
However, the ‘leaving right of way’ steps for traffic phases can be configured
differently for non UK controllers. Up to three configurable ‘steps’ can be configured.
The duration of one of those steps can be controlled by the ‘leaving amber time’,
although the controller can be configured to illuminate any aspects not just amber,
including flashing green for example.
The leaving amber time period is linked to the eight maximum green time sets (see
section 6.5.3) and thus different amber periods can be configured for different times
of day.
The timing range is 0 to 31.8 seconds in 0.2-second steps. Up to 8 times can be
configured for each phase (one for each ‘maxset’).
6.5.7 Inter-green (IGN)
The inter-green period is a safety period between one phase losing ROW and
another phase gaining ROW. Only conflicting phase to phase transitions can have
individual inter-green timing values.
No inter-green period is reduced below its value during phase changes. In the event
of different inter-green values to phases gaining ROW, the longest inter-green will
be effective.
If phases conflict, but due to stage movement restrictions, the phase to phase
transition never takes place, an inter-green value should still be configured, see
section 6.3.