Overview
Points (UK/India/Australia) or Switches (US/Canada) — together called Turnouts — are mechanical installations that allow a train to move from one track to another.
They are critical components of railway operations and must operate with extremely high reliability because:
A single incorrect point setting can cause a derailment or a collision.
Turnouts are closely monitored by the signalling system and interlocking to ensure safe route setting.
What Are Points / Turnouts?
A turnout consists of several key components that guide the train wheels from one track to another:
- Switch Rails / Point Blades
- Stock Rails
- Closure Rails
- Crossing / Frog
- Check Rails
- Drive Mechanism (manual or motor-operated)
- Detection System (ensures proper position)
Together, these elements form a safe and smooth pathway from the main track to a diverging track.
Why Turnouts Are Safety Critical
- A misaligned or unlocked point can cause a derailment
- Conflicting routes must be interlocked
- The system must prove the correct position before clearing a signal
- High-speed turnouts require special design to maintain stability
Turnouts are therefore a core input to interlockings.
Components of a Turnout
1. Switch Rails / Point Blades
The movable rails that guide the train onto the chosen route.
2. Stock Rails
Fixed rails against which the switch rails rest.
3. Crossing / Frog
The intersection where the running rails cross each other.
4. Check Rails
Ensures wheels stay correctly aligned through the crossing.
5. Drive Mechanism
Can be:
- Manual lever
- Electric motor
- Hydraulic drive
- Pneumatic drive
6. Detection System
Critical for safety — it reports the actual position of the points to the interlocking.
Types of Turnouts
1. Conventional Turnouts
Standard-speed turnouts used worldwide.
2. High-Speed Turnouts
Used where speeds of 100–200 km/h are required on diverging routes.
Features:
- Longer switch rails
- Tangential geometry
- Elastic fastening systems
3. Swingnose Crossings
Movable nose at the crossing to reduce impact and increase speed.
4. Single and Double Slip Turnouts
Used in complex station layouts to maximize flexibility.
5. Ladder Tracks and Scissors Crossovers
Often used in metro and commuter rail systems.
Point Operation Methods
1. Manual Operation
Used in:
- Rural lines
- Yards
- Low-speed sidings
Simple lever-based systems.
2. Electric Motor Operation
Most common on mainlines worldwide.
Provides:
- Remote operation from a signal cabin/control center
- Position detection
- Locking and monitoring
3. Hydraulic / Pneumatic Operation
Used in:
- Harsh climates
- Heavy-duty freight environments
- Locations requiring high force
Point Detection — Why It Matters
A signal cannot clear until the points:
- reach the required position
- are locked
- detection contacts verify the status
This prevents:
- run-throughs (when a train forces points apart)
- conflicting routes
- derailments
Detection is fail-safe:
If the system cannot confirm the position → treat as unsafe.
Point Locking (Absolute Requirement)
Points must be positively locked before a train passes.
Locking types:
- Mechanical locking
- Electrical locking
- Electromagnetic locking
- Hydraulic locking
Unlocked points = unsafe.
Common Failures and Safeguards
1. Failure to Move
- Motor unable to shift blades
- Mechanical obstruction
- Ice, snow, sand buildup
→ Interlocking will not clear the signal.
2. Detection Failure
- Broken wire
- Faulty detector
- Loose fitting
→ System fails safe → treated as “unknown” → no movement authority.
3. Run-Through
Train forces points out of position due to incorrect setting.
Modern points include:
- sprung switches
- run-through protection
- alarms to the interlocking
Where Turnouts Are Used
- Stations
- Yards
- Passing loops
- Crossovers
- Terminals
- Sidings
- Metro junctions
- High-speed corridor diverging routes
Turnouts define the flexibility of railway operations.
Country Variations
United States
- Term used is “switch”
- Heavy-duty turnouts for long, heavy freight trains
- Manual switches common on unsignalled territory
United Kingdom
- Long history of varied turnout designs
- Widespread use of electric motor-operated points
Europe
- Extensive use of high-speed turnouts
- Adherence to EN standards for geometry and safety
India
- Mix of conventional and motor-operated turnouts
- Heavier use of manual operation in yards and non-electrified routes
Japan
- High reliability mechanisms
- Rapid automatic reset for metro operations
Common Questions
Why can’t points move when a train is on them?
Because it can cause derailment or damage.
Interlockings prevent point movement during occupancy.
Do high-speed lines avoid turnouts?
They minimize them — but where needed, special high-speed turnouts are used.
Why are point failures common in winter?
Ice and snow can obstruct movement.
Heating systems are used in cold countries.
Can points be operated automatically?
Yes — many modern systems use automatic route setting (ARS).