Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 10 Page 80 of 265
b) Masking out phase demands,
c) Inserting stage demands,
d) Masking out extensions, i.e. causing them to be ignored,
e) Suspending maximum green times.
Thus for the above-mentioned modes, specific stages may be requested, and the
controller forced to serve them when required.
5.5.2 Usage of Stage Movement Restriction Tables
The controller will always use the stage movement restriction table, applicable to the
mode in which it is operating when it initiates the stage change.
EXAMPLE
If a priority demand invokes a stage change, the controller will be in priority mode
due to the priority demand and will use the stage change restrictions table
applicable to priority mode.
However, if the controller has already decided to make a stage change in the VA
mode and a priority demand is received, the controller will continue to make the VA
move although the mode will have changed. The controller will then only use the
stage movement restriction table applicable to priority mode if it makes any
subsequent moves whilst still in priority mode.
5.6 Parallel Stage Streaming
5.6.1 General
Parallel Stage Streaming provides independent control of up to 8 separate
intersections, later referred to as Streams, from one controller, i.e. the eight
intersections may be considered as being controlled by separate controllers, with
the exception of certain modes, see section 5.6.4.
This facility would normally be used if there were to be no cross-stream Phase
Conflicts. However, cross-stream Phase Conflicts and cross-stream Linking can be
covered by using cross-stream Phase Inter-green and Special Conditioning
Software.
5.6.2 Stage Streams
The controller will support up to 8 streams (numbered 0 to 7). Each stream may
contain any number of stages but no stage or phase may appear in more than one
stream and the total number of stages for all streams must not exceed 32.
If a stream requires an all red condition, a separate all red stage must be provided
for that stream.