Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 10 Page 107 of 265
7.3.6 UTC Demand Bits
These provide simulated on-street demands and/or extensions from the UTC
computer. In the case of pedestrian demands, the WAIT indicator will be illuminated
on receipt of the demand unless specifically requested otherwise.
7.3.7 Conditions Occurring
When demands and/or extensions are required to be inserted when certain
conditions occur, rather than the operation of detectors. For example, a stage
becoming active inserts a demand for a following stage.
7.3.8 Repeat Pulses
When controllers are linked together, demands and/or extensions can be inserted
when certain conditions occur in the first controller and the pulses are repeated to
the second controller. (See section 27.1).
7.3.9 SDE/SA
This facility provides extra extensions to phases for high-speed vehicles, see
section 9.
7.3.10 Handset
Fixed demands and extensions for phases may be inserted and removed via the
handset using the PHD and the PHE commands.
7.4 Pedestrian Demand Control
7.4.1 Introduction
In addition to pedestrian push buttons, the controller can be configured with ‘cycle
detectors’ and ‘kerbside detectors’. The controller firmware treats ‘cycle detectors’
and ‘push-button inputs’ the same and both should be configured to demand the
phase in the usual way.
‘Kerbside detectors’ allow the controller to cancel the demand (and switch off the
wait / demand indicator) if the pedestrian crosses before the pedestrian phase gains
right of way, see section 7.4.4.
A push button input can be associated with a specific kerbside input in order to
determine the type of pedestrian demand inserted (7.4.2). A kerbside input can be
associated with one or more push button inputs, or it can be associated with none in
which case it is only used to hold and cancel the demand (7.4.4).
“Figure 21 – Pedestrian Demand Processing” overleaf shows the pedestrian
demand processing performed by the firmware described in sections 7.4.2 to 7.4.4.