Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 11 Page 125 of 265
If phases E and F are required to always
appear at red/amber and then green
together, a gaining phase delay can be used
to delay the appearance of phase E.
If phase E is delayed by 4 seconds on the
move from stage 2 to stage 4, phases E and
F would appear at the same time.
Also see section 11.4 below…
11.4 Delay Timer
Whether a phase is losing or gaining ROW, the delay timer starts when the leaving
stage terminates.
If a phase losing ROW is delayed, it will be prevented from terminating (i.e. held at
green) for the delay period.
If a phase gaining ROW is delayed, it will be prevented from gaining ROW and thus
held at red (or blackout for green arrow phases) for the delay period. In this case the
delay time must include the longest inter-green time to the phase on this transition
plus the actual delay required. In the case of a traffic phase the red/amber time (i.e.
2 seconds) should be subtracted from the total sum.
In the example in section 11.3 above, it was required to delay phase E by just one
second. Therefore, the required gain phase delay period would be:
Inter-green from C to E:
5
Plus the required delay: + 1
Less the red/amber time:
– 2
Gives the delay period: = 4
Note: If phase E did not include a red/amber period, e.g. it was a non UK vehicle,
green arrow or pedestrian phase, the required gain phase delay period would be:
Inter-green from C to E:
5
Plus the required delay: + 1
(No red/amber time): – 0
Gives the delay period:
= 6
11.5 Phase Delay Handset Commands
There are four handset commands that can be used to specify phase delays or
modify information previously entered in the configuration.
Up to 120 entries can be made to specify the phase to be delayed (DFZ), how many
seconds it is delayed by (DPG), and on the move from which stage (DMF) to which
stage (DMT).
A
C
E
F
…Stage 2
AMBER
AMBER
R/A
R/A
Stage 4…
4 Second
Phase
Delay