Signals - 3 Position Signals Flashcards
What is the purpose of Track Circuits?
When a train enter the Track Section, the leading wheels move past the relay area and form a shortened circuit. This causes the signal to go in the Stop position
What is Axle Counter Technology?
- A sensor located at signals which records the number of axles as they pass that point.
- If the required number of axles are counted that signal will turn to Stop
What do 3 Position Signals allow?
Allow more information about the track section ahead to be passed on to the driver
What information do 3 Position Signals give to the driver?
Information about the:
- Points
- Track section ahead
- Speed
- Next Signal
What is the top light on a 3 Position Signal called?
“A” light
What is the bottom light on a 3 Position Signal called?
“B” light
What is the smaller additional light below the two lights on a 3 Position Home Signal called?
“C” light
When are Medium Speed aspects used?
- Junctions or Diverging Running lines
- Short track sections
What Type are all 3 Position Signals on the Metro Network?
Light Type
What are the 3 classes of Three Position Signals?
- Home
- Automatic
- Dwarf
Who are Home Signals controlled by?
Signaller (unless the Automatic “A” light is aluminated)
3 Position Signals are fixed at and protect?
- Stations
- Signal boxes
- Sidings
- Level crossings
- Junctions
Who must give authorisation to pass Home Signals at Stop?
Area Controller/Signaller
What are Automatic Signals primary purpose?
Speed up the passage of trains by dividing a long section of track into shorter sections
How May a driver pass an Automatic Signal at Stop?
Using Rule 1 Section 3
Who control Dwarf Signals?
Signaller
Dwarf Signals control train movements from:
- Running line to Running line
- Running line to Sidings
- Sidings to Running line
- Sidings to sidings
What are the two classifications of Fixed Signals?
- Absolute
- Permissive
What signals are considered Absolute?
Home, Dwarf and Disc
(Meaning a signaller needs to give them authorisation to pass Stop signal)
What signals are considered Permissive?
Automatic
(Meaning a driver can use Rule 1 Section 3 to give themself authorisation to pass Stop signal)
What are the coloured lights displayed on a 3 Position Signal called?
The Aspect
How many different combinations can a 3 Position Signal present?
- Home: 6 (7 if a Home signal has a “C” light)
- Automatic: 6
- Dwarf: 3
What aspects can be displayed on a Home or Automatic signal that has a Marker light as its lower light?
- Normal Speed
- Stop
What aspects can be displayed on a Home or Automatic signal that has a Marker light as its upper light?
- Medium Speed
- Stop