Hurry Call Mode; Selected Manual Control - Siemens ST950 Handbook

Selective Vehicle Detectors (SVD) or transponder interrogators which respond only to
the appropriate type of vehicle, i.e. buses for Priority mode and ambulances or fire
appliances for Emergency Vehicle mode, are used to distinguish the vehicles.
An operation of the priority vehicle detection equipment whilst the priority phase does
not have right of way will, in addition to registering as priority demand, register as a
normal demand. If a call/cancel unit normally calls the phase, a latching demand may
still be registered.
The presence of a Priority Demand will cause Priority or Emergency Vehicle mode to
become operational, subject to mode priority considerations. Right of way will then
normally go immediately to the Priority Phase, subject to any delay caused by minimum
green or inter-green periods timing off or any enforced stage sequences specified for
safety or other reasons. Normally, all VA extensions will be curtailed and any VA
demands will be skipped.
The Priority Unit will convert further outputs from the SVD while the Priority Phase has
right of way into Priority Extensions. The Priority Extensions will hold the Priority Phase
at right of way.
Any phases that have their VA extensions curtailed or their VA demands skipped may
be compensated next time they have right of way.
After a Priority Demand has been actioned, that demand and/or other Priority Demands
may be inhibited for a specified period.
19 H C
URRY
A 'hurry call' demand gives precedence to a particular stage to ensure that a green
signal is given to certain vehicles.
Hurry calls may be used at junctions, e.g. near to fire or ambulance stations, to ensure
that certain vehicles are given right of way, or in conjunction with queue detectors, to
prevent blocking of a junction.
Immediately a valid hurry call is received, the HURRY ACTIVE indicator on the Manual
Panel illuminates and remains illuminated until the end of the hold period. A hurry call
is valid provided its prevent timer is not active due to a previous hurry call and the
delay timer for any higher priority hurry call is not active. A cancel input for each hurry
call enables the process to be terminated any time during the delay, hold or prevent
periods.
20 S
ELECTED
Manual mode selected on the Manual Panel is recognised as a mode for priority
purposes. With the 'MANUAL' button pressed, manual mode will be selected providing
there are no operating conditions for a higher priority mode (see section 13).
During Manual mode, only 7 stages and the all-red condition (normally stage 0) are
available to be selected by means of buttons on the Manual Panel.
Security classification
Version
Last Editor
Document Name
Copyright © Siemens plc 2015. All Rights Reserved.
M
ALL ODE
M C
ANUAL ONTROL
Unrestricted
4
Paul Cox
ST950 General Handbook
Mobility Division, Traffic Solutions
Sopers Lane, Poole, Dorset, BH17 7ER
Page 81 of 107
Status Issued
Date 16-Jul-2015
Document No. 667/HB/46000/000
Mobility is a division of Siemens Plc