Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 11 Page 209 of 265
Wag signals, Wig-Wag Signals are also available with flashing blue aspects
(replacing the usual flashing red aspects) for use in these positions.
In countries where the UK specification TR2513 does not apply, the amber period
can be altered or removed, in similar ways to a traffic amber-leaving period.
The default flash period for the reds is 400mS (left) and 400mS (right). Longer flash
periods are available if required. However, it must be noted that all the flashing
signals displayed by a controller flash at the same rate.
28.5.4 Phase and Sensor Usage
Figure 36 – Wig-Wag Phases and Sensors
In order to provide the correct flashing sequence and be able to Red Lamp Monitor
the signals correctly, each pair of Wig-Wag Signals on one approach must be driven
by two adjacent phases and monitored by two adjacent sensor numbers. A maximum
of two red aspects per sensor can be monitored, i.e. two left reds by one sensor and
two right reds by the next sensor.
One approach (with two signals) is shown above. More than one approach can be
configured as required, up to the phase limit of the Traffic Controller. Each approach
requires two phases (and two on-board sensors).
If mimic signals are required to use phase outputs (rather than digital outputs) an
approach can be added to drive just those signals. In this case, lamp monitoring
would normally be disabled on both sensors of that ‘mimic’ approach.
On-Board
Sensor {n}
NC
NC = No Connection
NC
NC
Approach 1
Phase {x}
Phase {x+1}
On-Board
Sensor {n+1}