Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 11 Page 118 of 265
Note that if the inter-green is not dependent on the SDE/SA phase inter-green time
(because another losing phase has a longer inter-green time), the extra clearance
period may not actually delay the appearance of the gaining phase.
Also note that the inter-green from the vehicle phase to the pedestrian phase on a
stand-alone pedestrian stream is fixed at three seconds of all red if the SDE/SA is
configured, regardless of the PAR value (see section 6.11.4). The ‘extra clearance
period’ above is not required.
9.5 SDE/SA Parallel Stage Streaming Facilities
If a phase with SDE/SA is requesting extra clearance and so increasing the time in
its associated inter-green timer, it is possible to specify in the configuration data,
which delay timers (for phases gaining ROW) are to also be increased. In this way it
is possible to specify delay timers just for the phases appearing in a particular
stream, whilst not increasing those in other streams.
9.6 SDE/SA on Green Arrows
If SDE/SA is required on a green arrow phase, the phase should actually be
configured as a normal 3-aspect traffic signal (with only the green aspect connected
to lamps) so that the amber period described in (a) in section 9.4.2 is provided.
If red lamp monitoring is also required, it would normally register a fault if no red
lamps are fitted on a phase. In this case, the sensor monitoring this green arrow
phase should be explicitly changed from monitoring a normal traffic red, amber,
green phase to monitor a green arrow.
This should be achieved by creating a new lamp sequence based on the traffic
sequence but modified to change the sequence type from ‘vehicle’ to ‘green arrow
and the lamp monitored states from red, amber, green to green only’.
9.7 Common Approach Lanes
Where an assessor is associated with a number of phases, all the phases that
require speed extensions and extra clearance periods can be driven from that
assessor. If this is required, the termination of the phases should not be staggered.
9.8 Other Loop Spacing
12ft-loop spacing is the default, but the SDE/SA facility can be configured to operate
with 10ft-loop spacing. Note that all SDE/SA loops on the site must be 10ft-loop
spacing. However, it is recommended that all the loops are re-cut for 12ft-loop
spacing and the controller configured for 12ft operation.