Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 11 Page 248 of 265
38.2.2.3 RLM Delays and Intermediate Stages
When a stage to stage move is made via an intermediate stage, the RLM delays are
applied on the two stage moves independently. However, this can mean that the
terminating vehicle phases do not terminate on the same stage move in which the
conflicting pedestrian phases appear.
If the intermediate stage is an all-red stage that only appears for a short period, an
RLM delay between the vehicle phase and a dummy phase in the intermediate
stage should be configured. This delays the appearance of the intermediate stage
and thus the appearance of the phases in following stage.
38.2.3 Second Red Lamp Failures
38.2.3.1 Response to a Second Red Lamp Failure
To determine which phases are to be switched off or just inhibited by a second red
lamp fault, two items are required. One defines for each stream whether such faults
on that stream switch off or just inhibit phases. The second item defines which
phases are to be affected on a phase to phase basis.
If phases are inhibited, they are prevented from gaining right of way and thus remain
at red. In the UK this is used to prevent pedestrian phases with audibles or tactile
indications (see section 6.2.2) from gaining right of way if two or more red lamps
have failed on a conflicting vehicle phase. Other than this, the stream continues to
operate normally.
If phases are switched off, all their aspects are switched off such that the phase is
blacked-out. In the UK this is used to extinguish all the phases in a part-time (see
section 14) or stand-alone pedestrian stream (see sections 6.11 and 38.3) when two
or more red lamps fail on one of the vehicle phases.
The following table illustrates how the actions for second red lamp failures can be
configured: