ST750
G
ENERAL
H
ANDBOOK
667/HB/33750/000
Page 40
Issue 6
3.3.2 Pedestrian Demand Acceptance
For the purposes of this section, push button inputs include any demand inputs
assigned to a pedestrian phase, including for example inductive loops for cycles.
If no kerbside detectors are configured on the phase, pressing the push buttons
generates a latched demand for the pedestrian phase, which is only cleared when
the pedestrian phase gains right of way.
If kerbside detectors are configured on the phase, then the operation is as follows:
Every push button input and every kerbside input is configured with its own
extension period (which can be modified using the IPX handset command). The
extension remains active for the configured period after the input goes inactive.
An
unlatched demand
for the pedestrian phase is accepted and the wait / demand
accepted indicator illuminated when a push button (or its extension) and its
associated kerbside detector (or its extension) are both active at the same time. This
demand will be cancelled when all the kerbside inputs go inactive.
A
latched demand
for the pedestrian phase is accepted and the wait / demand
accepted indicator illuminated when a push button input is active but its associated
kerbside detector (and its extension) is inactive, or no kerbside detector has been
associated with that push button input. This demand is only cleared when the phase
gains right of way.
3.3.3 Pedestrian Demand Delay (PDD)
The transition from vehicle green to pedestrian green starts with the vehicle
changing to amber. A delay before starting this transition can be configured so that
the vehicle phase does not terminate as soon as the pedestrian push button is
pressed, although the wait indicator is illuminated.
The delay is controlled using the handset command PDD.
The controller uses the following rules:
•
In VA mode, if one or more real phases are at right of way (and none of the
phases at right of way have pre-timed maximums configured) the delay is not
applied, since if vehicles are present, their extensions will keep the vehicle
phase at green.
•
In VA mode, the controller will examine the maximum green timers of all
conflicting phases which are at right of way which have also been configured to
run a ‘pre-timed maximum’ but no ‘pre-timed extra period’ (see PTM and PTX in
section 3.2.3If any have expired or have less time to run than the delay, the
delay is introduced, otherwise all have more time to run than the delay, so no
delay is introduced and the controller will only allow the stage change if none of
the phases are being extended.
