Last reviewed 16 Sept 2026 · Facts as of 16 Sept 2026 · 11 min read
Points and crossings (turnouts)
Points and crossings enable trains to be diverted from one track to another. A turnout is the simplest arrangement, allowing a train to move from a main line to a branch line.
Components of a turnout
| Component | Function |
|---|---|
| Pair of points (switches) | Each consists of a stock rail and a movable tongue rail (switch rail); the tongue rails deflect the wheels to the main or diverging track |
| Lead rails (closure rails) | Rails between the heel of the switches and the crossing |
| Crossing (frog) | Allows wheel flanges of one track to cross the rail of the other; consists of a nose (splice and point rails) and wing rails |
| Check rails (guard rails) | Placed opposite the crossing on the outer rails to guide wheel flanges and prevent them from striking the nose |
| Heel block, stretcher bars, slide chairs, switch rods | Hold switches in position and allow movement |
Terms: toe of switch (thin end of the tongue), heel of switch (fixed end), throw of switch (distance through which the tongue moves at the toe), flangeway clearance and flangeway depth, theoretical nose (intersection of gauge lines) and actual nose (blunt nose, a short distance behind).
Types of switches
- Stub switch — ends of movable rails butt against fixed rails (obsolete).
- Split switch — tongue rails lie against stock rails: loose heel type (heel fish-plated) and fixed heel type (flexible tongue).
- By tongue design: undercut switch (foot of stock rail planed to accept tongue) and overriding switch (tongue rides over the foot of stock rail — stronger, used in modern designs).
- Straight and curved switches — curved switches allow higher turnout speeds.
Types of crossings
- Acute angle (V) crossing — the common crossing in turnouts.
- Obtuse angle (diamond) crossing — at diamond crossings (two tracks crossing each other).
- Square crossing — tracks crossing at right angles (avoided on main lines).
- By construction: built-up crossings (machined rails bolted together) and cast manganese steel (CMS) crossings (one-piece castings — very wear resistant, used on main lines).
Crossing number and angle
Crossing number (N) expresses the crossing angle (the angle between the running faces of the point and splice rails):
| Method | Relation |
|---|---|
| Right-angle (Cole's) method — used on Indian Railways | |
| Centre-line method | |
| Isosceles triangle method |
Standard crossings on Indian Railways include 1 in 8.5 (mostly in yards/goods lines), 1 in 12 (passenger running lines) and 1 in 16 (for higher turnout speeds). Flatter crossings (larger N) permit higher speeds but need longer turnouts.
Lead and radius of turnout (Coles' method, approximate)
- Curve lead:
- Radius of turnout curve:
- Lead (from the heel of switch to theoretical nose) = curve lead − switch lead
= gauge; = crossing number.
Speeds on turnouts are restricted according to crossing number and switch design (e.g. about 30 km/h for 1 in 12 turnouts with curved switches on BG, and lower for 1 in 8.5).
Track junctions and layouts
| Layout | Purpose |
|---|---|
| Turnout | Diverts trains from one track to another |
| Crossover | Two turnouts connecting two parallel tracks |
| Scissors crossover | Two crossovers superimposed with a diamond crossing — allows movement in both directions within a short length |
| Diamond crossing | Two tracks cross at an angle — two acute and two obtuse crossings |
| Diamond with slips (single/double slip) | Diamond crossing with connections allowing change of tracks |
| Gauntlet track | Two tracks overlap on a narrow bridge or restricted section without switches |
| Triangle | Three turnouts in a triangle — for turning locomotives or rakes |
| Turntable | Rotating platform for turning locomotives in limited space |
| Symmetrical split (Y-junction) | Both tracks diverge equally from the straight |
| Three-throw switch | Three routes from one set of points in restricted space |
| Double junction | Junction of two double lines |
Railway stations and yards
Purposes of stations
Exchange of passengers and goods; crossing and overtaking of trains on single lines; reception and despatch of trains; control of train movements; locomotive changing, watering and servicing; marshalling of wagons.
Classification
Operational (Indian Railways):
- Block stations — control train movement by the block system: Class A, Class B and Class C stations (Class C, e.g. block huts, do not deal with traffic).
- Non-block stations — Class D (flag stations/halts) where trains stop but no block working is done.
- Special class stations.
Functional: passenger stations, goods stations, junction stations (where lines meet), terminal stations (line ends), halt stations, flag stations, crossing stations, hill stations etc.
Platforms
- Passenger platforms — high-level platforms (on BG up to about 840 mm above rail level) for easy boarding; low- and rail-level platforms at smaller stations. Length suited to the longest trains (long-distance trains of 24–26 coaches need platforms of several hundred metres).
- Goods platforms — for loading/unloading at wagon floor level.
- Facilities: foot overbridges, subways, shelters, lighting, water, public address, signage.
Yards
| Yard | Purpose |
|---|---|
| Passenger yard | Reception, despatch and stabling of passenger rakes; carriage washing lines |
| Goods yard | Receiving, loading, unloading and delivery of goods |
| Marshalling yard | Sorting wagons into trains according to destination — flat yards (shunted by locomotives), gravity yards (natural slopes) and hump yards (wagons pushed over a hump and roll into sorting sidings by gravity — most efficient) |
| Locomotive yard (loco shed) | Servicing, fuelling and repair of locomotives |
Station equipment and safety features
- Buffer stops — at dead ends of tracks.
- Fouling marks — indicate the limit beyond which vehicles on one track would foul the other.
- Sand humps, scotch blocks, derailing switches — prevent runaway vehicles from fouling running lines.
- Catch sidings and slip sidings — on steep gradients to trap runaway trains.
- Water columns, weigh bridges, loading gauges, end loading ramps, cranes.