
Key components of Points and Crossings in Railway Engineering – essential for safe train movement and JKSSB Civil exam preparation.
📘 What are Points and Crossings?
In a railway track system, points and crossings are vital infrastructural elements that enable trains to move from one track to another or to traverse intersecting tracks with safety and continuity. These systems are indispensable at junctions, yards, and stations, ensuring operational flexibility and enhancing the capacity of the railway network. Their precise design and installation help prevent derailments, minimize delays, and support the efficient scheduling and routing of trains across complex railway layouts.
🔍 Definition:
“Points and crossings are arrangements of rails that facilitate the transfer of train movement from one track to another or enable smooth traversal across intersecting tracks.”
⚡️ Why Are Points and Crossings Necessary?
Railways are not just parallel tracks—they form networks of interconnected routes that must handle various dynamic situations. Trains need the ability to:
- Switch directions based on scheduling or route changes
- Access multiple platforms at stations to accommodate different services
- Change routes in marshalling or shunting yards for goods and passenger sorting
- Bypass faulty or under-maintenance sections without halting overall operations
- Handle heavy traffic during peak hours or emergencies efficiently
Without points and crossings, flexibility, operational reliability, and safety in railway systems would be severely compromised. These components allow seamless integration of new lines, support emergency rerouting, and optimize platform and track utilization—all critical to a modern and high-capacity railway system.
🧹 Detailed Components of Points and Crossings
1️⃣ Switch (Points)
A switch is a mechanical installation on a railway track that enables trains to be diverted from one track to another. It consists of movable rails, called tongue or switch rails, which guide the train wheels onto a different track based on operational needs. Switches are operated manually or automatically and play a crucial role in train routing, yard operations, and safe passage through junctions. Their design must ensure smooth transition, minimal wear, and reliable functioning under repetitive dynamic loads.
Key Parts:
- Tongue Rails (Switch Rails): Movable rails that guide wheels onto the desired track. These rails taper from the thicker heel section to a thin toe and move laterally to divert the train wheels toward a desired route. They must be properly maintained to ensure precision, reduce wear, and prevent derailment.
- Stock Rails: Fixed rails against which the tongue rails rest. They provide the necessary lateral support for the switch rails and are rigidly held in position. Stock rails are engineered to resist wear and maintain gauge integrity even under heavy loads.
- Heel of Switch: The joint where the tongue rail is hinged or connected. It marks the rear end of the switch assembly where flexibility is required to allow the movement of the switch rails. The design of the heel should ensure accurate alignment, minimal vibration, and durability under repeated switching operations.
- Stretcher Bar: Connects both tongue rails to ensure simultaneous movement. It ensures that the two switch rails move in unison—when one rail closes against the stock rail, the other opens. Stretcher bars are key to maintaining correct track gauge and preventing derailments. They may also include locking and detection systems in advanced rail networks.
2️⃣ Crossing (Frog)
A crossing allows the inner wheels of a train to cross from one track to another at an intersection, especially where two railway lines intersect at grade. It is a critical component for ensuring continuity of movement when tracks intersect, as it accommodates the flanged wheels of the train while maintaining alignment and gauge.
Key Parts:
- Vee (Nose) of Crossing: The sharp or blunt point where two rails intersect. It forms the crossing point and must be robust to withstand repeated impacts from train wheels. In high-speed tracks, this is often made of cast manganese steel.
- Wing Rails: These are specially bent rails on both sides of the vee that support the train wheels as they pass through the crossing. They prevent the wheel from hitting the nose directly and help in smooth transition.
- Check Rails: These are placed parallel to the wing rails to guide the wheels and restrict lateral movement. They ensure that the wheel flanges follow the correct path and prevent derailment, especially at the gap near the vee where no support rail exists.
♻️ Types of Crossings – Explained
Type | Diagram Suggestion | Description |
---|---|---|
Acute Angle Crossing | 🔺 Simple ‘X’ intersection | Used where tracks intersect at a sharp angle |
Obtuse Angle Crossing | ➖⏘ Crosses at >90° angles | Common in yard layouts |
Diamond Crossing | ❎ Two tracks cross each other | No connection—used in complex junctions |
Scissors Crossing | 🔀 Combines two crossovers | Saves space in congested yards/stations |
Cross-over | ↔️ Allows movement between parallels | Pair of turnouts facing opposite directions |
🧲 Turnout Terminology – Must-Know for JKSSB
Term | Meaning |
Turnout Number (e.g. 1 in 12) | Ratio between length of switch lead and track divergence |
Lead Length | Distance between the toe of switch and nose of crossing |
Heel Divergence | Lateral distance between switch rails at heel end |
Throw of Switch | The distance the tongue rail shifts to enable a route change |
Flange Way Gap | The clearance for wheel flanges to pass without hitting other rails |
📊 Design Principles
- Minimum Wear and Tear: Alignment should be smooth to reduce impact and wear on components. Misalignment can lead to excessive vibration, noise, and rapid degradation of the switch and crossing parts, especially under high-speed or heavy-axle load operations. Use of high-quality materials and precision installation is key.
- Safe Divergence Angle: Divergence angle must allow for safe transition at moderate speeds. A steeper angle may permit compact layouts but compromises on speed and safety. Turnouts are classified based on their divergence angles (e.g., 1 in 8.5, 1 in 12), with flatter angles preferred on main lines to facilitate higher speeds.
- Adequate Flange Clearance: Ensure no contact between wheel flanges and check rails. Sufficient clearance prevents friction, noise, and structural damage while allowing smooth passage of flanged wheels through the crossing without jumping off the track.
- Proper Maintenance: Regular lubrication, alignment checking, and bolt tightening are essential. In addition, ultrasonic testing, inspection of locking mechanisms, replacement of worn-out components, and real-time condition monitoring through sensors and IoT-based systems are increasingly being adopted to ensure high reliability and safety in modern rail networks.
⚙️ Materials Used in Points and Crossings
Component | Preferred Material |
Tongue & Stock Rails | High Carbon Manganese Steel |
Frog (Crossing Nose) | Hardened Cast Manganese Steel |
Check Rails | Rolled Steel with Heat Treatment |
Switch Mechanism | Galvanized Iron, Steel, or Electromechanical Systems |
⚡️ Mechanism of Operation
- Manual Operation: Levers and rods, usually in small stations or yards. Manual switches are operated by station staff or railway workers using mechanical linkages such as hand levers. These are cost-effective but slower, requiring physical presence for activation.
- Power Operated Switches: Used in high-traffic stations and mainline networks; powered by electricity or hydraulics. These switches are faster, can be operated remotely from control rooms, and are integrated into signaling systems for improved efficiency and safety.
- Electronic Interlocking: Controls multiple points remotely and ensures no conflicting train paths are set. It is a microprocessor-based system that coordinates switch and signal operations, reducing human error. Electronic interlocking is essential for managing high-speed rail corridors, metro systems, and dense junctions with complex track layouts.
🚧 Maintenance of Points and Crossings
Points and crossings are subject to high stress and heavy wear due to frequent train movement, wheel impact, and switching force. These areas are particularly vulnerable to fatigue and material failure, making regular inspection and upkeep essential for ensuring operational safety and longevity.
Key maintenance activities include:
- Greasing and lubrication of movable parts to reduce friction and wear, especially in tongue rails and stretcher bars.
- Replacement of worn-out tongue rails to prevent derailment and maintain smooth switching operations.
- Alignment and gauge checking to ensure the track geometry remains within permissible limits, reducing risk of derailment.
- Fastening inspection and tightening, as loose fastenings can cause misalignment or component failure.
- Ensuring obstruction-free flange ways, which is vital for unimpeded passage of wheel flanges through crossings.
- Ultrasonic flaw detection to identify internal cracks or fatigue in rails and crossings.
- Monitoring with sensors and IoT systems, especially in high-speed networks, for real-time diagnostics and preventive maintenance planning.
📈 Practical Applications and Real-World Examples
Location | Type Used | Purpose |
Railway Station Platforms | Scissors Crossing, Crossovers | Flexibility in train arrivals and departures |
Marshalling Yards | Turnouts, Diamond Crossings | Handling goods wagons efficiently |
Metro Rail Systems | Power-operated switches | Automated control and high-speed operations |
Junction Stations (e.g., Delhi) | Complex Crossings | Management of train traffic from multiple lines |
🧐 Sample MCQs for JKSSB Civil (With Explanations)
Q1. The movable tapered rail in a turnout is known as?
- A) Wing rail
- B) Check rail
- C) Tongue rail ✅
- D) Frog
Explanation: Tongue rail is the movable part that diverts train wheels.
Q2. Which of the following prevents derailment at crossings?
- A) Check rail ✅
- B) Stock rail
- C) Lead rail
- D) Switch rail
Explanation: Check rail controls wheel flange movement at crossings.
Q3. What is the purpose of a diamond crossing?
- A) Crossing for river
- B) Two tracks cross each other ✅
- C) Reversal of direction
- D) Increase train speed
Explanation: Diamond crossing allows two tracks to cross at the same grade.
📌 Conclusion
Understanding Points and Crossings is essential for any civil engineer working with railway systems, especially in India where railway infrastructure forms the backbone of national transport. These components not only determine operational efficiency but also significantly influence safety and routing flexibility.
For JKSSB JE Civil aspirants, this is a high-priority topic due to its technical depth, frequent inclusion in exams, and direct applicability in fieldwork during government service.
By mastering the types, components, and design considerations, you’re not only preparing for the exam but also equipping yourself with essential practical knowledge that will be invaluable in future site inspections, maintenance planning, and infrastructure development projects under the Public Works or Railways Department.