Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 11 Page 124 of 265
11.3 Phases Gaining Right-Of-Way
The inter-green times from conflicting phases determines at which point a phase
gains ROW. If phases gaining ROW have different inter-green times from a
conflicting phase, they will gain ROW at different points. The time differences will be
the same every time the phase to phase transition occurs regardless of the stage to
stage transition.
However, if it is required that a certain phase appears at ROW later than its inter-
greens would allow on a certain stage to stage transition, a ‘gaining phase delay’
can be configured to delay the appear of the phase.
For example, it may be required that two or more phases appear at ROW at the
same instant on a certain stage to stage transition, but the inter-greens to those
phases would allow one phase to appear before the other.
Consider the 4-stage intersection below:
A
C
E
F
…Stage 2
AMBER
AMBER
R/A
A
B
F
A
C
D
C
G
FE
Stage 1 Stage 2 Stage 3 Stage 4
R/A
Stage 4…
C
D
E
F
…Stage 3
AMBER
AMBER
R/A
R/A
Stage 4…
Intergreen between phases A to E = 5s
Intergreen between phases C to E = 5s
Intergreen between phases C to F = 6s
Intergreen between phases C to E = 5s
Intergreen between phases C to F = 6s
Intergreen between phases D to E = 6s
Figure 27 – Delay Phase Gaining Right Of Way
The shorter inter-greens from phases A and C to E mean that on the move directly
from stage 2 to stage 4, phase E appears one second before phase F.
While on the move from stage 3 to stage 4, the 6 second inter-green from phase D
to phase E forces phase E to appear at the same time as phase F.