Selected Fixed Time, Clf Or Va Mode; Cableless Linking Facility (Clf) Mode; Vehicle Actuated (Va) Mode - Siemens ST950 Handbook

22 S
ELECTED
Manually selected 'FT', 'CLF' and 'VA' are selected by mode select buttons on the
standard intersection manual panel (see section 33).
The respective mode will only become operative if 'SELECTED FIXED TIME, CLF or
VA' mode is a higher priority than the current mode.
These mode select buttons may be used to force the controller to work in VA, CLF or
FT mode rather than in a mode that would normally be higher in priority than VA, CLF
or FT such as UTC or Priority for example. Because VA or FT is usually configured as
the lowest priority mode, SELECTED VA/FT/CLF is treated as a separate mode, and
can be configured higher up in the mode priority table.
23 C
ABLELESS
The 'Cableless Linking Facility' (CLF) allows a method of linking traffic intersections
along routes within an area using timing information derived from the 'Master Time
Clock System' (see section 28) in their controllers. Different Plans are used during the
day to cater for varying traffic patterns.
Each CLF Plan has its own configurable 'cycle time'. At configured times (known as
'group times') within this cycle time, 'group influences' are programmed to affect the
operation of the controller.
Thus, at a particular time of day, a pre-defined plan can be introduced to enforce a set
of fixed duration effects on the controller.
Therefore, several controllers can each have 'Plans' designed for them. If they are all
introduced at pre-determined times and synchronised by an accurate Master Time
Clock System in each controller, it can be seen that the actions of the controllers can
be co-ordinated, so as to create a fixed time form of control for a whole area.
New features available from Issue 6 onwards:
Smooth CLF – available for base-time CLF and provides smooth entry into and
between CLF plans.
CLF Step Size – allowing either a cycle time of up to 250 seconds in 1 second
steps, or a cycle time of up to 500 seconds in 2 second steps.
24 V A
EHICLE
In VA mode the controller monitors all demands, extensions and maximum green
timers every 200 ms to select a suggested stage in order to satisfy as many demands
as possible without missing any stage containing a phase with a demand.
If each phase only resides in one stage, each stage will continue until there is a
demand for a phase not at right of way (but also see the Arterial Reversion facility)
Even when there is a demand, the stage will continue until all the phases that are at
right of way can be terminated. If a phase still running its minimum green time or a
Security classification
Version
Last Editor
Document Name
Copyright © Siemens plc 2015. All Rights Reserved.
F T , CLF
IXED IME
L F
INKING ACILITY
(VA) M
CTUATED
Unrestricted
4
Paul Cox
ST950 General Handbook
Mobility Division, Traffic Solutions
Sopers Lane, Poole, Dorset, BH17 7ER
VA M
OR ODE
(CLF) M
ODE
ODE
Page
Status
Date
Document No.
Mobility is a division of Siemens Plc
83 of 107
Issued
16-Jul-2015
667/HB/46000/000