Indian Culture & Heritage — Arts & Traditions

Why This Chapter Matters

This is the chapter that decides whether you pass the ALP and Technician technical round or not. Railway recruitment boards pull 10 to 15 questions from signaling, traction, and safety protocols in almost every CBT-2 paper for Assistant Loco Pilot, and the Technician (Electrical/Mechanical) exams lean on it just as hard. Skip this chapter and you are gambling with a fourth of your technical score.

Here is the trap almost every aspirant falls into: they memorize signal colours and Kavach features as isolated facts, then freeze when a question links two ideas together, like "what should a driver do when a signal fails AND the crossing gate is open." Real exam questions test judgment built on facts, not the facts alone. Read this chapter the way a loco pilot reads the track ahead: as one connected system, not a list of trivia. By the end, you should be able to picture a train approaching a station, see the signals change colour in your head, and know exactly what the driver does at each stage.

1. Signal Types: The Railway's Traffic Language

A railway signal is nothing but a coded instruction the track gives the driver from a distance, because a train cannot stop the way a car does. A loaded freight rake needs over a kilometre to halt from full speed. That single fact explains almost the entire signaling system: every rule exists to give the driver enough warning, early enough, to slow down safely.

Colour-Light Signals

Indian Railways runs almost its entire network today on colour-light signaling, replacing the older semaphore arms in most sections. A colour-light signal uses electric lamps (increasingly LED units now) showing standard colours, and each colour is an instruction, not a suggestion.

• Red: Stop. The train must not pass this signal under any circumstance without proper authority.
• Yellow (single): Caution. Proceed, but be prepared to stop at the next signal, which may be red.
• Double Yellow: Attention. The next signal is showing a single yellow, so you get two signals of advance warning before an actual stop signal. This exists because high-speed sections need more braking distance.
• Green: All clear. Proceed at the permitted speed for that section.

Memory hook: Think of the sequence as a car slowing into a red light in stages: Green you cruise, Yellow (double) you ease off the accelerator, Yellow (single) you cover the brake, Red you stop. Say it as "GYYR — Go, Yield twice, Rest." That order mirrors exactly how a train's braking distance is built up signal by signal.

Exam trap: Students often confuse "double yellow" with "flashing yellow." Indian Railways primarily uses steady double yellow as an advance caution before a single yellow, while flashing indications are used in specific contexts like an approaching diverging route at a junction. Do not treat every yellow variant as identical; read the question stem for whether it says flashing or steady.

Colour-light signals are further classified by their operational role:

Signal Type	Purpose
Outer Signal	First stop signal a train meets before entering a station area, tells the driver whether the route ahead is clear
Home Signal	Controls entry into the station itself
Starter Signal	Permits the train to leave the station and enter the block section ahead
Advanced Starter	Positioned beyond the starter, confirms the train has fully cleared station limits before entering the next block

A station approach, read left to right in a driver's mind, goes Outer, Home, Starter, Advanced Starter. That is the fixed order a train physically passes through, and questions frequently ask you to identify which signal governs which stage.

Semaphore Signals: The Older Language

Before colour-lights took over, Indian Railways used semaphore signals: a mechanical arm mounted on a post, its position telling the driver what to do. Some smaller and older sections still retain them, so the exam expects you to know the basics.

A semaphore signal has two working positions:

• Horizontal arm: Danger, meaning stop. This is the default "fail-safe" position; if the mechanism breaks, the arm falls to horizontal, automatically showing stop.
• Arm lowered at 45 degrees: Proceed, the line is clear.

At night, semaphore signals use lamps behind coloured glass to replicate the same meaning: red light for horizontal (stop), green light for the lowered/clear position. This is worth remembering because it explains why colour-light signaling and semaphore signaling share the same red-and-green logic even though the daytime indicator (arm position versus lamp colour) is different.

Exam trap: A semaphore signal defaults to danger when it fails, not to clear. This "fail-safe" design is a favourite exam question, because it tests whether you understand why the system is built that way: gravity pulls a broken or powerless arm down to horizontal, which is the stop position, so any mechanical failure automatically protects the train rather than endangering it.

Special-Purpose Signals

Beyond the main running signals, a handful of special-purpose signals appear often enough in exam questions that you should recognize them by name and function.

• Calling-On Signal: A subsidiary signal mounted below a main signal, usually showing a small illuminated white or yellow indication when active. It permits a train to move cautiously into an already-occupied platform line, at a very restricted speed, typically to allow it to be attached to a stationary rake or to pull up behind another train under full visual control of the driver.
• Shunt Signal: Governs shunting movements (locomotives or wagons being moved within yard limits, not full running movements between stations) and is deliberately kept distinct from main signals so that yard staff and drivers never confuse a shunting permission with a mainline "proceed."
• Repeater Signal: Used where sighting distance to a main signal is poor, for example around a curve or under a bridge, repeating that main signal's aspect earlier so the driver is not caught by surprise.

Exam trap: A calling-on signal is not a substitute for a main signal being clear; it is a deliberately restrictive indication, permitting movement only at very low speed and only under specific operational conditions, precisely because the line ahead may already have another train standing on it. Questions sometimes present a calling-on signal as equivalent to a green "all clear," which is incorrect.

2. Interlocking: Making Wrong Moves Physically Impossible

Interlocking is one of those railway concepts that sounds technical but is genuinely simple once you see the logic. Interlocking is the arrangement of signals, points (the moving rail sections that switch a train from one track to another), and locks so that they can only be operated in a sequence that keeps the train safe, and any unsafe or conflicting combination is physically or electrically blocked.

Picture a large station with several platforms and criss-crossing tracks. If the signalman could set a green "proceed" signal on one line while simultaneously leaving the points open toward a track already occupied by another train, you would have a collision waiting to happen. Interlocking removes that human error from the equation. Before the system allows a signal to show "clear," it first checks, mechanically or electronically, that every point along that route is correctly set and locked, and that no conflicting route is active at the same time.

Think of interlocking like a strict school hall monitor at exam time: a student is not allowed into the exam hall (the signal cannot turn green) until every desk (every point) is confirmed properly arranged, and two students are never let into the same seat (no two trains get routed onto the same section) at once. The monitor does not trust anyone's word; the check is automatic.

There are two broad implementations you should know:

• Mechanical interlocking: Signals and points are connected to levers in a cabin through rodding and wires, physically interlocked so that levers can only be pulled in a permitted sequence.
• Electrical/Route Relay Interlocking (RRI) and Panel Interlocking (PI): Modern stations use electrical relays or computer-based systems (Solid State Interlocking, or SSI) where a signalman selects a route on a panel or screen, and the system itself checks all safety conditions before setting the signal to clear.

Exam trap: Do not confuse interlocking with Kavach (covered later in this chapter). Interlocking prevents conflicting routes and points within a station or yard. Kavach is a train protection system that prevents collision between two trains on the open line, largely through automatic braking. They work at different scales and one is not a substitute for the other; a modern safe railway needs both.

3. Level Crossing Protocols

A level crossing is where a road crosses the railway track on the same level, and it remains one of the highest-risk points on the entire network because it is the one place where road users and trains share the same space. ALP and Technician exams test level crossing rules heavily because loco pilots must react correctly to them every single trip.

Level crossings in India fall into two broad categories:

• Manned level crossings: Staffed by a gateman who operates the gates by hand or by lever, closing them to road traffic before a train passes and reopening them after. These are further classified by traffic volume into "Special Class," "A," "B," "C," and "D" categories, which determine staffing and interlocking requirements.
• Unmanned level crossings (LC gates): No gateman present; the road user is expected to stop, look, and cross only when safe. Indian Railways has been eliminating unmanned crossings on broad gauge routes for years precisely because they cause a disproportionate share of accidents.

Exam trap: A commonly tested distinction is between an "interlocked" level crossing gate and a plain manned gate. An interlocked gate is electrically connected to the signaling system so that the protecting signal cannot show "clear" unless the gate is actually closed to road traffic. A non-interlocked manned gate relies purely on the gateman's manual action, with no electrical safety check tying gate position to signal aspect. Interlocked gates are considered significantly safer because they remove reliance on human timing alone.

For a loco pilot, the standard protocol approaching any level crossing includes:

1. Sounding the whistle well in advance as a warning, at the prescribed whistle board.
2. Observing the gate is closed (for manned crossings) or that the crossing is clear (for unmanned ones) before proceeding, regardless of signal indication, as a personal double-check.
3. Never assuming a green or proceed signal alone guarantees the level crossing is properly secured; interlocking reduces risk but professional vigilance remains mandatory.

Real-world grounding: you have almost certainly waited at a railway gate in a small town, watching the gateman close the barrier by hand as a whistle sounds in the distance. That everyday scene is exactly the manned-crossing protocol the exam is testing, just seen from the passenger's side of the barrier instead of the driver's cab.

4. Overhead Electrical Traction (OHE): How the Train Gets Its Power

Most of the Indian Railways network today runs on electric traction, drawing power from an Overhead Equipment (OHE) system, sometimes still called OHE or the "overhead wire." Understanding how it works, and more importantly how to stay safe around it, is core ALP and Technician material.

How OHE Works

The OHE consists of a system of wires suspended above the track, carrying high-voltage electricity, typically 25 kV AC on Indian Railways' broad gauge electrified sections. A pantograph, the diamond or single-arm frame mounted on the roof of the locomotive, presses upward against the contact wire and draws current from it, completing the circuit through the rails back to the traction substation.

Picture it like a trolley pole on an old-style tram, except scaled up massively in voltage and engineered to stay in contact with the wire even as the train moves at 100-plus km/h and the wire itself sways slightly with wind and temperature. The contact wire is not a single flat cable; it is supported by a "catenary" wire above it through periodic droppers, keeping the contact wire at a near-constant height so the pantograph maintains steady contact without excessive arcing.

Memory hook: Remember "CPS" for the three physical layers, top to bottom: Catenary wire (support), Pantograph (the train's contact arm), Substation (the power source feeding the whole loop). The catenary holds the contact wire steady, the pantograph reaches up to touch it, and the substation is where the 25 kV originates.

OHE Safety Rules

This is where exam questions get specific, and where real-life safety depends on getting it exactly right.

• 25 kV is lethal at a distance, unlike household current. Electricity at this voltage can arc, meaning it can jump through air to a nearby conductive object without direct contact. Indian Railways safety codes specify a minimum safe clearance distance from any live OHE component; railway staff are trained never to assume "not touching it" means "safe."
• Before any maintenance work on or near the OHE, the section must be de-energized and earthed (grounded) by the authorised traction power controller, and a "caution order" or equivalent permit issued. Nobody works on a "possibly live" wire; it must be confirmed dead and earthed first.
• Loco pilots are trained to never climb onto the locomotive roof or touch any roof-mounted equipment without confirmation that the OHE supply to that section is switched off, even if the train itself is stationary.
• In case of OHE wire snapping or falling onto or near the train, standard protocol is to stay inside the coach/cab, avoid touching the coach body or any metal part connected to the exterior, and await instructions, because a broken live wire can energize the metal body of a stopped train or nearby structures.

Exam trap: A frequently tested number is the standard AC traction voltage on Indian Railways' electrified broad gauge network, which is 25 kV AC, single phase, at industrial frequency of 50 Hz. Do not confuse this with the older DC traction voltage (1500V DC) that was historically used in some sections like Mumbai suburban before conversion to AC; a question may specifically ask which system Indian Railways transitioned toward, and the answer is AC traction at 25 kV as the current standard.

5. ALP-Specific Safety Protocols

An Assistant Loco Pilot's day does not start when the train moves. It starts well before that, with a defined checklist, because a small oversight before departure can become a major incident hundreds of kilometres down the line.

Before Starting Duty

Standard pre-duty protocol for a loco pilot and assistant loco pilot includes:

1. Reporting on time and undergoing a breath analyser test to confirm fitness for duty; alcohol tolerance for safety-critical railway staff is effectively zero.
2. Collecting and reviewing the caution order, a document listing all speed restrictions, temporary works, and special instructions for the section to be run that trip.
3. Checking the locomotive itself: brake system function, headlights, horn, pantograph condition, and that all safety equipment (fire extinguisher, first aid kit, detonators for emergency signaling) is present and functional.
4. Verifying the vacuum or air brake pressure is built up to the correct working level before the train is permitted to move, since a train cannot depart safely with inadequate brake pressure.
5. Confirming the route knowledge for the section, since loco pilots are only permitted to run on routes they hold a valid "road learning" certificate for; running an unfamiliar route without qualification is a serious violation.

Exam trap: Questions sometimes ask what a caution order actually contains. It is not a general rulebook; it is a trip-specific document listing precise locations of speed restrictions and known temporary hazards for that particular run. Confusing the caution order with the General and Subsidiary Rules (which are the standing rulebooks governing all operations, not trip-specific) is a common wrong-answer trap.

Emergency Braking Procedures

When something goes wrong on the line, whether it is an obstruction ahead, a signal failure, or mechanical trouble, the loco pilot's response follows a defined hierarchy rather than a single panic action.

• Emergency brake application: bringing the train to a stop as quickly as possible using full brake application, which is more aggressive and faster-acting than normal service braking but comes with higher risk of wheel-slide (skidding) and greater mechanical stress.
• Protecting the train: once stopped, standard protocol requires the crew to protect the train from both directions where relevant, historically using detonators (small explosive charges placed on the rail that produce a loud bang when run over, warning an approaching train's driver) placed at a prescribed distance behind and ahead of the stopped train, along with hand signals or flags.
• Informing the control office/station: communicating the situation to the nearest station or the section controller at the earliest opportunity, using the available communication system (radio, GSM-R, or the nearest available means), so that other trains on the section can be held or warned.
• Not restarting until cleared by the appropriate authority, since resuming movement without clearance after an emergency stop risks running into whatever caused the stop in the first place, or moving against a still-unresolved hazard.

Real-world grounding: think about how a school fire drill has a fixed sequence, alarm, evacuate, headcount, all-clear, rather than everyone just running in different directions. Emergency braking protocol on the railway works on the same principle: a fixed, drilled sequence beats improvisation when seconds and lives are at stake.

Memory hook: Remember the order as "S-P-I-N": Stop (emergency brake), Protect (detonators/signals both directions), Inform (control/station), No restart without clearance. A stopped train that has "spun" through this sequence has done everything correctly.

6. Kavach: India's Anti-Collision System

Kavach (meaning "armour" or "shield" in Hindi) is Indian Railways' indigenously developed Automatic Train Protection (ATP) system, and it is one of the most important recent developments for any current-affairs-aware exam aspirant to know cold, because it appears in both technical and general awareness sections.

What Kavach Does

Kavach is designed to prevent train collisions caused by a loco pilot missing or misjudging a signal, one of the most dangerous single points of human error in railway operation. It works through a combination of onboard locomotive equipment, trackside equipment, and radio communication (using ultra-high frequency, UHF, radio) to continuously exchange data between the locomotive, the signaling system, and other trains in the vicinity.

In simple terms, Kavach constantly knows where a train is, what speed it is doing, what the signal ahead is showing, and whether another train is within an unsafe distance on the same line. If the loco pilot fails to apply brakes in response to a restrictive signal (say, running toward a red signal without slowing), Kavach automatically applies the brakes itself, well before the train reaches the signal, preventing a Signal Passed at Danger (SPAD) incident from becoming a collision.

Analogy: Think of Kavach as a strict co-pilot sitting beside the driver who never gets tired and never looks away from the track. A human driver might get distracted, misread a signal in poor visibility, or simply be a split second late reacting. Kavach does not blink; it watches the signal aspect and train speed every moment, and steps in the instant a mismatch appears, exactly like a vigilant co-pilot grabbing the wheel when the primary driver is about to make a mistake.

Key Functions of Kavach

• Automatic braking when the driver does not respond appropriately to a stop or restrictive signal.
• Prevents SPAD-related collisions, historically one of the leading causes of serious train accidents in India.
• Prevents collision between two trains approaching each other or following each other too closely on the same line, by continuously sharing location and speed data between trains fitted with Kavach in the same section.
• Automatic whistling at level crossings, so the system also assists in reducing accidents at unmanned or poorly monitored crossings.
• Continuous display of relevant signal information in the driver's cab, called cab signaling, which is useful in conditions of poor visibility like fog, when a lineside signal may be hard to see from a distance but the cab display still shows it clearly.

Exam trap: Kavach is often confused with the European Train Control System (ETCS), a broadly similar concept used internationally. Kavach is India's own indigenously developed system, built to Indian Railways' specific safety and interoperability standards, and questions testing current affairs or railway modernization will specifically want you to identify it as an indigenous development, a point Indian Railways and the Research Designs and Standards Organisation (RDSO) have emphasized repeatedly, rather than an imported foreign system.

Exam trap: Another frequent confusion is between Kavach and Kavach's predecessor concepts like TCAS (Train Collision Avoidance System), which was an earlier name/version of essentially the same indigenous development effort before it was renamed and standardized as Kavach. If a question mentions TCAS, treat it as the developmental precursor to today's Kavach system rather than a separate unrelated technology.

Why It Matters for Your Exam and Your Career

Kavach is being progressively rolled out across high-density and high-speed routes on Indian Railways, and as an ALP or Technician, you may well work on or alongside Kavach-fitted locomotives and sections during your career. Beyond the exam marks, understanding what the system actually does, and more importantly its core philosophy of automatic intervention when a human misses a critical safety cue, will make you a better and safer railway employee from day one.

Quick Revision — One-Line Facts

1. Red signal means stop; a train must never pass it without proper authority.
2. Single yellow means caution, be ready to stop at the next signal.
3. Double yellow gives two signals of advance warning before an actual stop signal.
4. Green means proceed at the permitted section speed.
5. The station approach order is Outer, Home, Starter, Advanced Starter.
6. A semaphore signal's horizontal arm position means danger/stop.
7. A semaphore signal's failure default is horizontal (stop), a fail-safe design.
8. Semaphore signals use red and green lamps at night behind coloured glass.
9. Interlocking prevents conflicting routes and points from being set simultaneously.
10. Mechanical interlocking uses levers connected by rodding; electrical/relay and Solid State Interlocking (SSI) use relays or computers.
11. An interlocked level crossing gate is electrically tied to the protecting signal.
12. Unmanned level crossings have no gateman and are being progressively eliminated on broad gauge.
13. Level crossings are classified into categories like Special, A, B, C, D by traffic volume.
14. Loco pilots must whistle at the whistle board before approaching a level crossing.
15. Indian Railways' standard AC traction voltage is 25 kV, single phase, at 50 Hz.
16. The pantograph draws power from the contact wire and returns current through the rails.
17. The catenary wire supports the contact wire through droppers to keep contact height steady.
18. OHE sections must be de-energized and earthed before maintenance work begins.
19. Loco pilots undergo a breath analyser test before duty as part of the pre-duty check.
20. The caution order is a trip-specific document listing speed restrictions for that run.
21. A loco pilot must hold valid route knowledge/road learning certification for the section run.
22. Emergency braking is more aggressive than normal service braking and risks wheel-slide.
23. Detonators are placed on the rail to warn an approaching train's driver during protection.
24. A train must not restart after an emergency stop without clearance from the proper authority.
25. Kavach is Indian Railways' indigenous Automatic Train Protection (ATP) system.
26. Kavach automatically applies brakes if a loco pilot fails to respond to a restrictive signal.
27. Kavach helps prevent Signal Passed at Danger (SPAD) related collisions.
28. Kavach uses UHF radio communication between locomotives, trackside units, and stations.
29. Kavach also provides cab signaling, showing signal status inside the driver's cab.
30. TCAS was the earlier developmental name for what is now standardized as Kavach.

Memory Tables

Table 1: Signal Aspects and Meanings

Signal Aspect	Meaning	Driver Action
Red	Stop	Must not pass without authority
Single Yellow	Caution	Proceed, prepare to stop at next signal
Double Yellow	Attention	Proceed, next signal will be single yellow
Green	Clear	Proceed at permitted speed
Semaphore horizontal	Danger	Stop
Semaphore lowered 45°	Clear	Proceed

Table 2: Station Signal Sequence and Function

Signal	Position	Function
Outer Signal	Before station limits	First stop signal, governs entry into station area
Home Signal	At station entry	Controls entry into the station itself
Starter Signal	At platform/departure end	Permits departure into the next block section
Advanced Starter	Beyond starter	Confirms full clearance of station limits

Table 3: Pre-Duty Loco Pilot Checklist Summary

Step	Action	Why It Matters
1	Breath analyser test	Confirms fitness, zero alcohol tolerance
2	Collect caution order	Know trip-specific speed restrictions
3	Check locomotive systems	Brakes, lights, horn, pantograph, safety kit
4	Verify brake pressure	Train cannot depart with inadequate pressure
5	Confirm route knowledge	Only certified routes may be run

Table 4: Kavach Core Functions

Function	Purpose
Automatic braking	Stops train if driver misses a restrictive signal
SPAD prevention	Reduces Signal Passed at Danger collisions
Inter-train collision prevention	Shares location/speed data between trains
Automatic whistling	Alerts road users at level crossings
Cab signaling	Displays signal status inside the cab, helpful in fog

Practice MCQs

Q1. What does a single steady yellow colour-light signal instruct a loco pilot to do? (a) Stop immediately (b) Proceed and prepare to stop at the next signal (c) Proceed at maximum speed (d) Reverse direction

Q2. In a colour-light signal sequence, what does a double yellow aspect indicate? (a) The next signal is red (b) The next signal is single yellow (c) The line is permanently closed (d) A level crossing is ahead

Q3. What is the correct sequence of signals a train encounters approaching and leaving a station? (a) Home, Outer, Starter, Advanced Starter (b) Outer, Home, Starter, Advanced Starter (c) Starter, Outer, Home, Advanced Starter (d) Outer, Starter, Home, Advanced Starter

Q4. A semaphore signal arm, if the operating mechanism fails, falls to which position by design? (a) 45 degrees lowered (b) Vertical (c) Horizontal (danger) (d) It stays in its last position

Q5. What is the primary purpose of railway interlocking? (a) To reduce electricity consumption (b) To prevent conflicting routes and points from being set at the same time (c) To control ticket booking (d) To synchronise train timetables only

Q6. What distinguishes an interlocked level crossing gate from a plain manned gate? (a) It has a different colour barrier (b) It is electrically connected so the signal cannot clear unless the gate is closed (c) It does not need a gateman at all (d) It only operates at night

Q7. What is the standard traction voltage used on Indian Railways' electrified broad gauge AC sections? (a) 1500V DC (b) 11 kV AC (c) 25 kV AC (d) 33 kV DC

Q8. Which locomotive component draws power directly from the OHE contact wire? (a) Catenary (b) Pantograph (c) Traction substation (d) Dropper

Q9. Before maintenance work is carried out on an OHE section, what must be done first? (a) The train schedule must be published (b) The section must be de-energized and earthed (c) The pantograph must be raised (d) Nothing extra is needed if the train is stationary

Q10. A caution order issued to a loco pilot primarily contains what information? (a) General disciplinary rules (b) Trip-specific speed restrictions and temporary hazards for that section (c) Ticket fare charts (d) Locomotive manufacturing details

Q11. During an emergency stop, what is the standard next step after applying the emergency brake and stopping the train? (a) Immediately restart after a short pause (b) Protect the train from both directions using detonators/signals (c) Disembark all crew and leave the train (d) Wait without informing anyone

Q12. What does Kavach primarily protect against? (a) Ticketless travel (b) Collisions caused by missed or misjudged signals (c) Track corrosion (d) Fare evasion

Q13. Kavach automatically applies brakes under which condition? (a) Whenever the train exceeds any speed at all (b) When the loco pilot fails to respond appropriately to a restrictive signal (c) Only inside tunnels (d) Only during night operation

Q14. What communication technology does Kavach primarily use to exchange data between locomotives and trackside equipment? (a) Bluetooth (b) UHF radio (c) Satellite phone only (d) Wired telegraph

Q15. TCAS is best described in the context of Kavach as what? (a) An unrelated foreign train control system (b) The earlier developmental name for the same indigenous system now called Kavach (c) A ticketing software (d) A type of level crossing gate

Answer Key

Q	Answer	Reason
1	(b)	Single yellow means caution, proceed but be ready to stop at the next signal.
2	(b)	Double yellow warns that the following signal will show single yellow, giving extra braking distance.
3	(b)	The fixed order a train passes through is Outer, Home, Starter, Advanced Starter.
4	(c)	Semaphore signals are fail-safe; mechanical failure drops the arm to horizontal, meaning danger/stop.
5	(b)	Interlocking exists to make conflicting signal and point combinations physically or electrically impossible.
6	(b)	Interlocked gates tie gate position to the signal electrically, so the signal cannot clear unless the gate is shut.
7	(c)	Indian Railways' standard AC electrification voltage is 25 kV AC, single phase, 50 Hz.
8	(b)	The pantograph presses against the contact wire to draw current into the locomotive.
9	(b)	Safety protocol requires the OHE section to be confirmed de-energized and earthed before any work begins.
10	(b)	A caution order is trip-specific, listing speed restrictions and temporary hazards, unlike the standing rulebooks.
11	(b)	After stopping, the crew must protect the train from both directions using detonators or signals/flags.
12	(b)	Kavach is designed to prevent collisions arising from a driver missing or misjudging a signal.
13	(b)	Kavach intervenes with automatic braking specifically when the driver does not respond to a restrictive signal.
14	(b)	Kavach relies on UHF radio communication to exchange real-time data between train, track, and station.
15	(b)	TCAS was the developmental precursor project that was later standardized and renamed Kavach.