Specifications
ST900 Family General Handbook
667/HB/32900/000 Issue 11 Page 203 of 265
2
2
8
8
A
A
L
L
T
T
E
E
R
R
N
N
A
A
T
T
I
I
V
V
E
E
S
S
I
I
G
G
N
N
A
A
L
L
S
S
E
E
Q
Q
U
U
E
E
N
N
C
C
E
E
S
S
A
A
N
N
D
D
F
F
L
L
A
A
S
S
H
H
I
I
N
N
G
G
S
S
I
I
G
G
N
N
A
A
L
L
S
S
28.1 Alternative Signal Sequences (Non UK Only)
For the UK, the signal sequences are fixed and cannot be changed. For non UK
use, there are 8 easily definable lamp sequences, with each phase assigned one of
these lamp sequences. Each lamp sequence set defines the signal states (i.e.
colours) for at right of way, at no right of way and the Part-time (standby) state. It
also defines the power on sequence, the signals off to on sequence, the sequence
from normal operation to Part-time and back to normal operation, as well as the
sequences between “at right of way” and “at no right of way”. Each sequence can
consist of up to 3 steps where the signal states and times can be specified.
Green must always be used for “at right-of-way” for traffic, pedestrian & green arrow
phases because of the green conflict facility.
Traffic Phases
Some examples of alternative signal sequences are:
Example 1 Example 2
at no ROW:
RED RED
changing to ROW:
RED RED
at ROW:
GREEN GREEN
changing to no ROW:
AMBER GREEN/AMBER
In both examples, the omission of RED/AMBER for “changing to ROW” does not
affect the length of the inter-green.
In the second example, the GREEN/AMBER would normally be the same value as
AMBER LEAVING, i.e. 3 seconds.
The RED/AMBER and AMBER LEAVING periods in the standard signal sequence
are fixed at 2 seconds and 3 seconds respectively and the rest of the lamp
sequence is fixed in order to conform to U.K. requirements. These values may be
changed in order to meet other specifications if required. For example, it is possible
to specify a variable amber leaving time in a similar way to specifying pedestrian
blackout times (see the LAT handset command).
Pedestrian Phases
The standard signal sequence for pedestrian phases does not allow for an amber to
appear in the “changing to right-of-way” and “changing to no right-of-way”
sequences since the amber is utilised to drive the wait indicator on a pedestrian
phase.
An example of a pedestrian signal sequence is:
at no ROW:
RED MAN
at ROW:
GREEN MAN