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Safety-critical technical reference — read before use. Independent educational guidance for qualified AGL and aerodrome personnel. It is not an approved procedure, design, specification or regulatory instruction and does not replace your aerodrome’s permit-to-work, isolation/LOTO procedures, the approved design or the manufacturer’s instructions. Series-circuit AGL equipment can carry lethal voltages. Read the full disclaimer ↓
THE AGL ENGINEERING CENTRE by Precision AGL Academy · Taxiway Lighting Systems

Taxiway Lighting Systems

The visual guidance system for safe aircraft movement on the ground. Taxiway lighting provides pilots with continuous visual guidance while aircraft taxi between runways, aprons, terminals and other operational areas — particularly during darkness and reduced-visibility conditions. It's not a row of lights along a pavement; it's an integrated system of geometry, fixtures, series circuits, CCRs, isolation transformers, cables, connectors, signs, control, monitoring and photometric performance.

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Overview

What Is a Taxiway Lighting System?

A taxiway lighting system is the coordinated arrangement of visual aids used to identify taxiways, provide directional guidance and assist aircraft movement on the aerodrome surface.

Depending on the airport configuration and applicable operational requirements, a taxiway system may include taxiway edge lights, taxiway centreline lights, stop bars, runway guard lights, centreline lead-on lights, centreline lead-off lights, illuminated taxiway signs, runway designation signs, information signs and other associated visual aids. The exact configuration depends on the taxiway layout, operational requirements, visibility conditions and applicable standards.

Not Just a Row of Lights

A taxiway lighting system is an integrated system involving geometry, fixtures, series circuits, CCRs, isolation transformers, cables, connectors, signs, and control & monitoring.

Continuous Guidance

Once an aircraft leaves the runway, pilots still need continuous visual information to navigate the airport surface safely.

Verified, Not Assumed

A light being ON does not automatically mean it is performing correctly — electrical testing, inspection and photometry confirm actual performance.

Purpose

Why Taxiway Lighting Is Important

Once an aircraft leaves the runway, pilots still need continuous visual information to navigate the airport surface. Taxiway lighting helps pilots understand where they are, where they should go, and where they must stop.

Where is the taxiway?

Edge and centreline lighting define the usable pavement and the intended taxi path.

Where are its edges?

Edge lights mark the lateral boundary of the taxiway, particularly in darkness and low visibility.

Which direction to follow?

Centreline and lead-on/lead-off lighting give directional continuity through the route.

Where does it meet a runway?

Intersection lighting coordinates taxiway, holding position and runway protection.

Where must it stop?

Stop bars provide a defined, controlled stopping point ahead of a runway or restricted area.

Which route to take?

Signs and lighting work together to communicate the correct taxi route to the pilot.

The Complete Chain

Taxiway Lighting System at a Glance

A simplified electrical architecture connects the airport power supply all the way through to the pilot's visual guidance.

AIRPORT POWER SUPPLY
AGL CONTROL SYSTEM
CONSTANT CURRENT REGULATOR
SERIES CIRCUIT
ISOLATION TRANSFORMERS
TAXIWAY LIGHT FIXTURES
OPTICAL OUTPUT
PILOT VISUAL GUIDANCE

For systems incorporating enhanced control functions — such as stop-bar switching or route-based centreline selection — the architecture may also include dedicated control, switching and monitoring interfaces.

Core Elements

Main Taxiway Lighting Elements

Each element of a taxiway lighting system serves a distinct guidance function. Together they form a continuous visual language for ground movement.

Taxiway Edge Lights

Identify the lateral boundaries of a taxiway, giving pilots visual information about the usable taxiway area — particularly during darkness and reduced visibility. Colour and placement depend on the applicable requirements.

Taxiway Centreline Lights

Provide guidance along the intended aircraft taxi path and are particularly important where enhanced visual guidance is required. Colour characteristics can vary by location and function.

Centreline lighting provides directional guidance, not simply pavement illumination.

Centreline Lead-On Lighting

Guides an aircraft from one taxiway route toward another operational route — particularly useful where geometry requires clear directional guidance. Design considers geometry, intersections, sequence, colour and control.

Centreline Lead-Off Lighting

Assists aircraft leaving a runway and transitioning onto a taxiway, creating a visual connection from runway → runway exit → taxiway through the transition.

Stop Bar Lighting

Provides a control point at taxiway/runway intersections and other designated locations, typically using red lighting to indicate where aircraft should stop. Part of runway-incursion prevention, not just another taxiway light.

Runway Guard Lights

Provide additional visual warning at runway/taxiway intersections, drawing attention to the runway holding position. May use elevated fixtures, inset fixtures, or other configurations depending on the system.

COMPLETE TAXIWAY LIGHTING SYSTEM RUNWAY A B → BLUE EDGE LIGHTS · OMNIDIRECTIONAL SIGNS GREEN CENTRELINE LIGHTS INTERMEDIATE HOLDING POSITION LIGHTS STOP BAR · RED RUNWAY GUARD LIGHTS · YELLOW EXIT LIGHTS · GREEN / YELLOW AIRFIELD LIGHTING CONTROL SYSTEM · SELECTIVE SWITCHING · STOP-BAR INTERLOCK · MONITORING EDGE CIRCUITBLUE EDGE LIGHTSCENTRELINE CIRCUITSSWITCHED BY SECTIONSTOP-BAR CIRCUITINTERLOCKEDHOLDING & GUARD CIRCUITYELLOW LIGHTSSCHEMATIC · LAYOUT, SPACING AND CIRCUIT COUNT ILLUSTRATIVE · NOT TO SCALE
Figure 1. No single light does the whole job. Blue edge lights define the pavement, green centreline lights give the path, exit lights and stop bars manage the way on and off the runway, and one control system ties the circuits together.AGL Visual Encyclopedia: What does a complete taxiway lighting system look like?
Stop Bars & Guard Lights

Operational Control at the Runway Boundary

Stop Bar Coordination

A stop bar's design must be coordinated with taxiway centreline lighting, runway protection, the control system, ATC operational procedures, monitoring and switching logic.

Runway Guard Purpose

Runway guard lighting serves a purpose fundamentally different from ordinary taxiway edge lighting — it exists specifically to draw pilot attention to the holding position.

The Runway Holding Position — Plan View

Taxiway centreline leads to the stop bar; runway guard lights flank the holding position just before the runway edge

TAXIWAY CENTRELINE STOP BAR Runway guard light (flashing) Runway guard light (flashing) HOLDING POSITION RUNWAY Taxiway edge lights — blue
The stop bar and runway guard lights work together with taxiway centreline and control logic — an aircraft should not cross an illuminated stop bar without ATC clearance.
Visual Coding

Taxiway Lighting Colours

Colour is an important part of the visual coding system. Different colours may identify different functions or locations. Colour selection should always be based on the specific lighting function and applicable ICAO, FAA, national and project requirements.

Taxiway Guidance Runway-Related Areas Stop Bars Centreline Transitions Lead-On / Lead-Off Guidance Other Visual Aids
Colour Reference

Taxiway Light Colours: Edge, Centreline, Stop Bar & Guard Lights

A quick reference for taxiway light colour (color) by function. Exact colour, extent and applicability depend on the lighting function and the applicable ICAO, FAA or project requirement.

LightColourWhat it tells the pilot
Taxiway edge lightsBlueMarks the edges of the taxiway
Taxiway centreline lightsGreenMarks the taxiway centreline for the pilot to follow
Lead-off centreline lightsAlternating green and yellowMarks the part of the exit centreline inside the ILS/MLS critical or sensitive area (first light green, last light yellow)
Stop bar lightsRedTells the pilot not to cross the holding position without clearance
Runway guard lightsYellow (flashing)Warns that the pilot is approaching a runway holding position
Intermediate holding position lightsYellowMarks an intermediate holding position on the taxiway

Quick Answers

Taxiway edge light color: blueTaxiway centerline color: greenStop bar light colors: redRunway guard light colors: yellow

What is the difference between runway edge and taxiway edge lights?

Runway edge lights are white, turning yellow near the end of an instrument runway, and define the runway limits. Taxiway edge lights are blue and define the taxiway limits. The two also differ in typical intensity and the standards that apply, so one must never be substituted for the other.

What is the difference between runway centerline and taxiway centerline lights?

Runway centerline lights are white, then alternate red and white, then red toward the runway end. Taxiway centerline lights are green, with alternating green and yellow (first light green, last light yellow) where the line lies inside the ILS/MLS critical or sensitive area on a runway exit. The colours are different, so the pilot always knows which kind of surface they are on.

WHAT EACH COLOUR MEANS, AND WHERE YOU SEE IT PLAN VIEW · LANDING LEFT TO RIGHT · ILLUSTRATIVE, NOT TO SCALE PAPI: WHITE ABOVE · RED BELOW OBSTACLE LIGHT: RED BEACON: WHITE / GREEN RUNWAY EDGE: WHITE CAUTION ZONE: YELLOW RUNWAY END: RED APPROACH LIGHTS: WHITE SIDE ROWS: RED (CAT II/III) CENTRELINE: WHITE → RED/WHITE → RED TOUCHDOWN ZONE: WHITE THRESHOLD + WING BARS: GREEN GUARD LIGHTS: YELLOW TAXIWAY EDGE: BLUE RUNWAY-SIDE CENTRELINE: GREEN / YELLOW STOP BAR: RED TAXIWAY CENTRELINE: GREEN WHITE THE RUNWAY ITSELF RUNWAY EDGE CENTRELINE TOUCHDOWN ZONE APPROACH · PAPI YELLOW CAUTION EDGE, FINAL ZONE GUARD LIGHTS INTERMEDIATE HOLDING ILS-AREA CENTRELINE GREEN GO · SAFE PATH RUNWAY THRESHOLD THRESHOLD WING BARS TAXIWAY CENTRELINE LEAD-ON LIGHTS RED STOP · DANGER RUNWAY END STOP BARS CENTRELINE LAST ZONE OBSTACLES · PAPI LOW BLUE TAXIWAY EDGE TAXIWAY EDGE LIGHTS NEVER ON A RUNWAY OMNIDIRECTIONAL WHITE = RUNWAY · YELLOW = CAUTION · GREEN = GO · RED = STOP · BLUE = TAXIWAY EDGE
Figure 2. Colour is the first thing a pilot reads on an airfield at night. White, yellow, green, red and blue each carry a fixed meaning, so the colour of a light says what kind of surface it marks and what to do next.AGL Visual Encyclopedia: What does each AGL colour mean, and where is it used?
Holding Position Systems

Stop Bar Lighting System & Runway Guard Light System: Colours & Installation

How stop bars and runway guard lights are arranged, coloured and installed at a runway holding position. See also Runway Guard Lights & Stop Bars.

Stop Bar Lighting System

A stop bar lighting system is a row of red lights across the taxiway at the holding position, switched on to stop traffic and off to let it proceed. It is controlled together with the taxiway centreline lights beyond it.

Stop Bar and Runway Guard Light Colors

Stop bar lights are red, shown toward the approaching aircraft. Runway guard lights are yellow and flash alternately, so that the two systems are not confused with each other.

Runway Guard Light System

A runway guard light system is installed at a runway holding position, either as a pair of elevated flashing lights at the sides of the taxiway or as a row of in-pavement lights across it.

Runway Guard Light Installation

Runway guard light installation and stop bar installation both depend on correct base position, aiming toward the approaching aircraft, cable routing and connection to the control system. Mistakes in any of these show up as poor visibility or wrong switching.

Switching & Control

Stop bars are normally switched in sections through the control and monitoring system, with the logic coordinated with the centreline lights and ATC procedures.

Verification

Stop bar and guard light installations are checked for colour, aiming, intensity and correct switching during commissioning and periodically after that.

Layout & Intersections

Taxiway Lighting Layout

Taxiway lighting must follow the physical geometry of the airport: centreline, edges, curves, intersections, holding positions, runway intersections, apron connections, aircraft stand routes, taxiway widths and associated signs.

A fixture may be electrically perfect but still provide poor guidance if it is incorrectly located or aligned.

Intersections require special attention because multiple aircraft routes converge. The design coordinates taxiway edge, taxiway centreline, runway holding position, stop bar, runway guard lights, taxiway signs and control logic. A poorly coordinated intersection can create confusing visual information even when every individual light is operating correctly.

Taxiway Intersection — Lead-On / Lead-Off Guidance

Lead-off guidance curves an aircraft off the runway onto the taxiway; lead-on guidance directs it onward to the next route

RUNWAY LEAD-OFF LEAD-ON — toward next route CENTRELINE CONTINUES Intersection SIGN
The portion of exit centreline lighting inside the ILS/MLS critical or sensitive area (or the inner transitional surface limit, whichever the standard applies) is alternating green and yellow, beginning with green and ending with yellow; the continuing taxiway centreline (lead-on) is green. Exact colour, extent and applicability depend on the runway/taxiway category and the applicable ICAO/FAA/project requirement.
RUNWAY · WHITE EDGE LIGHTSSTOP BARHOLDING POSITION MARKINGRUNWAY GUARD LIGHTSGREEN CENTRELINE CURVES ONTO THE RUNWAYLINK TAXIWAYPARALLEL TAXIWAYTO APRON ►◄ FROM APRONBLUE EDGE LIGHTS · GREEN CENTRELINE LIGHTSPLAN VIEW · ILLUSTRATIVE, NOT TO SCALE
Figure 3. Green centreline and blue edge lights mark the route, and red stop bars and yellow guard lights protect each runway entry.AGL Visual Encyclopedia: How are taxiway lights laid out?
Layout Details

Intersections, Holding Positions, Signs, Bases & Aiming

The detail that turns a taxiway lighting layout into usable guidance.

Taxiway Runway Intersection Lights

Taxiway runway intersection lights are the lead-on and lead-off centreline lights, holding position lights and stop bars where a taxiway meets a runway. Coordinate them with the signs and the control logic.

Taxiway Holding Position Lights

Taxiway holding position lights include the stop bar and runway guard lights at a runway holding position, and intermediate holding position lights elsewhere. Their colour and switching must be consistent with the signs.

Taxiway Straight Section Lighting

Taxiway straight section lighting uses wider centreline spacing than curves, where lights are placed closer together to follow the turn. Exact spacing comes from the applicable standard.

Taxiway Lighting Signs

Taxiway lighting signs are illuminated location, direction and destination signs that work with the lights to guide the pilot. See taxiway guidance signs.

Runway Lighting Signs

Runway lighting signs, such as runway designation and holding position signs, are the signs found at runway entry points. They are signs, not lights, but they are designed together with the runway-related lighting.

Taxiway Light Aiming & Alignment

Taxiway light aiming and taxiway light alignment matter most for unidirectional lights such as stop bars and some centreline fixtures. Blue edge lights are omnidirectional and mainly need correct position and height.

Taxiway Light Base

The taxiway light base is the in-ground base or can that carries the fixture and receives the cable connection. Correct base position, depth and orientation make correct aiming and sealing possible.

TAXIWAY / TAXIWAY INTERSECTION DIRECTION OF TAXI CLEARANCE BAR 3 FIXTURES · YELLOW · ACROSS CENTRELINE SITED AT SUFFICIENT DISTANCE FROM THE INTERSECTION EDGE LIGHTS TRACE THE CORNER RADIUS CENTRELINE CURVES THROUGH SPACING CLOSER ON THE CURVE SCHEMATIC VIEW OF A TAXIWAY/TAXIWAY INTERSECTION · FIXTURE COUNT, CURVE RADIUS, AND SPACING ILLUSTRATIVE · NOT TO SCALE
Figure 4. At a taxiway intersection, several independent lighting systems layer on top of one another — edge lights outline the pavement shape, centreline lights curve through with reduced spacing, and holding-position lighting appears wherever the intersection requires a stop or extra caution.AGL Visual Encyclopedia: How does taxiway intersection lighting work?
Design

Taxiway Lighting Requirements, Design & Circuit Design

Requirements and design decisions that come before any fixture is installed.

Taxiway Lighting Requirements

Taxiway lighting requirements depend on the operations the taxiway serves, such as night or low-visibility movements, the taxiway type and the applicable ICAO, FAA or national standard. See Standards Companion.

Taxiway Lighting Design

Taxiway lighting design sets the fixture types, spacing, colours, intersections, holding positions and signs for the airport layout. It is coordinated with the control logic and the circuit design.

Airport Lighting Circuit Design

Airport lighting circuit design groups lights into series circuits, sizes the CCR and cable, and decides how circuits are split so one fault does not blank a whole taxiway. See AGL Design & Electrical Engineering.

AGL Design Basics

The AGL design basics are layout, colour coding, series circuit design, control and the checks that confirm the result. The same principles apply across taxiway, runway and approach systems.

Halogen Taxiway Lights

Halogen taxiway lights use lamps that need regular replacement and draw more power than LED fixtures. LED conversion is a common upgrade, with the circuit load and CCR compatibility (minimum load, power factor, waveform) rechecked afterwards.

Coordination

Requirements, design and operations have to agree, so the lighting is coordinated with markings, signs, the stop bar logic and the ATC procedures.

TAXIWAY CIRCUIT ARRANGEMENT AIRFIELD LIGHTING VAULTCCR 1 · EDGECCR 2 · CENTRELINECCR 3 · STOP BARS EDGE CIRCUIT · ONE LOOP, BOTH EDGES CENTRELINE CIRCUIT · SWITCHED BY SECTION STOP-BAR CIRCUIT · INTERLOCKED WITH CENTRELINE BEYOND HOLDING POSITION ONE FIXTURE ON THE SERIES LOOP ISOLATING TRANSFORMERLAMP LAMP FAILS → LOOP STAYS CLOSED SCHEMATIC · CIRCUIT COUNT AND ROUTING ILLUSTRATIVE · NOT TO SCALE
Figure 5. Behind every taxiway light is a constant-current series loop. Edge lights, centreline lights and stop bars each get their own circuit, every fixture connects through an isolating transformer, and the system is split into zones so a fault stays local.AGL Visual Encyclopedia: How is a taxiway lighting circuit arranged?
Core Concept

The Taxiway Series Circuit

Many taxiway lighting systems use series circuits, allowing multiple fixtures to operate as part of a single controlled constant-current circuit while remaining electrically isolated from the primary loop.

CCR
Series Cable
Isolation Transformer
Taxiway Fixture
Isolation Transformer
Taxiway Fixture
Return
SERIES LOOP · THE PRINCIPLE ONE LOOP · ONE CURRENT · EQUAL LIGHT CCR I FIXED OUT RTN I I I T1 SAME LIGHT T2 SAME LIGHT T3 SAME LIGHT T4 SAME LIGHT 1 THE CCR SENDS ONE CURRENT AROUND THE LOOP 2 THE SAME CURRENT PASSES EVERY LIGHT IN TURN 3 SAME CURRENT = SAME BRIGHTNESS THE PRINCIPLE ONE LOOP, ONE CURRENT LIGHTS CONNECTED END TO END THE RESULT EQUAL BRIGHTNESS WHATEVER THE POSITION OR CABLE LENGTH THE TRADE-OFF ONE BREAK STOPS THE LOOP SO THE LOOP MUST STAY COMPLETE SCHEMATIC · LOOP SHORTENED · NOT TO SCALE
Figure 6. Lights connected end to end on one loop with one current — so every light gives the same output.AGL Visual Encyclopedia: What is the AGL series circuit principle?
Circuit Components

CCR, Isolation Transformers & Connectors

Constant Current Regulator

Provides controlled current to the series circuit. The system may use different intensity levels depending on operational requirements. CCR design should consider fixture count and load, transformer characteristics, circuit length, total circuit load, required intensity steps, and control & monitoring requirements — not simply fixture count.

Isolation Transformers

Provide the electrical interface between the primary series circuit and individual fixtures (Series Circuit → Transformer Primary → Transformer Secondary → Fixture). Selection should be coordinated with fixture rating, circuit current, secondary requirements, installation conditions and the applicable specification.

Connectors

Interface between series-circuit cable, isolation transformer and fixture (primary connector, secondary connector, plug, receptacle, connector kits). A poor connector causes high resistance → heating → intermittent operation → fixture failure → circuit problems, so inspection is a key part of maintenance.

Control & Intensity

Taxiway Lighting Control

Taxiway lighting can be integrated with the airport's AGL control system. Enhanced taxi guidance systems may require more sophisticated control logic than a simple lighting circuit.

Control Functions

Circuit ON/OFF Intensity Selection Centreline Control Stop Bar Control CCR Control Route Switching Status Indication Fault Indication Remote Monitoring

Intensity Concept

Low

Reduced output

Medium

Increased output

High

Higher conspicuity

Operations

Taxiway Lighting Remote Control & ALCMS

How taxiway lighting is selected, switched and monitored from a distance.

Taxiway Lighting Remote Control

Taxiway lighting remote control lets the tower or a control room switch taxiway circuits, select routes and change intensity without anyone going to the substation. It is the normal way taxiway lighting is operated.

Taxiway Lighting ALCMS

Taxiway lighting ALCMS means the airfield lighting control and monitoring system that provides this remote control and reports circuit status, current and faults back to the operator. See ALCMS.

ALCMS-TO-TAXIWAY · SEGMENTS AND STOP BARS ALCMS TAXIWAY CONTROL SEGMENT 1 LIT · ROUTE SEGMENT 2 LIT · ROUTE SEGMENT 3 OFF STOP BAR HOLDING POSITION STOP BAR COMMAND RUNWAY STATUS RETURNS FOR EACH SEGMENT AND THE STOP BAR ROUTE SEGMENTS LIT TO GUIDE HOLD STOP BAR ON = STOP CLEAR STOP BAR OFF = PROCEED KEY POINT A STOP BAR AND THE LIGHTS BEYOND IT WORK AS A PAIR — STATUS MUST CONFIRM BOTH SCHEMATIC PLAN · WHERE STOP BARS ARE FITTED · NOT TO SCALE
Figure 7. Switching taxiway lights by segment to show a route, and stop bars to hold or clear an aircraft — with the true state of each part reported back.AGL Visual Encyclopedia: How does the ALCMS control the taxiway?
Interactive

Taxiway Circuit Load Estimator

CCR selection should be based on the actual system design rather than simply the number of lights. Adjust the sliders to see how fixture count, unit load and estimated circuit losses combine into a total circuit requirement.

40 fixtures
45 VA
8%
Fixture Load
0 kVA
Estimated Losses
0 kVA
Total Circuit Requirement
0 kVA
Teaching estimate only. Real CCR sizing also adds isolating-transformer efficiency and magnetising loss, series-cable I²R loss at the selected current step, and spare capacity, and is then matched to a standard CCR kW rating from the design and manufacturer data.
Verification

Photometry & Electrical Testing

A taxiway light being ON does not automatically mean that it is performing correctly. Electrical testing, visual inspection and photometry together provide a complete picture of taxiway lighting performance.

Photometry

Evaluates intensity, distribution, colour, alignment, fixture-to-fixture variation and overall system performance. A fixture can appear normal on visual inspection yet produce significantly lower intensity than expected.

Electrical Testing

Series-circuit continuity, insulation resistance, cable testing, isolation transformer testing, connector inspection, CCR testing, circuit current verification, control-system testing, monitoring/fault verification, and earthing & bonding checks where applicable.

Mechanical Inspection

Fixture housing, lens, optical surfaces, mounting, alignment, fasteners, frangible components, water ingress, corrosion, cable entry and connector condition. Taxiway fixtures are exposed to aircraft, vehicle, weather and maintenance activity.

Testing

Taxiway Lighting Tests: Acceptance, Electrical, Insulation, Continuity & Test Report

The tests that sit alongside photometry and commissioning for a taxiway lighting system.

TestPurposeNote
Taxiway lighting commissioning testConfirms the installed system works as designed before handoverPart of the commissioning sequence
Taxiway lighting acceptance testFormal check against the specification for acceptance by the ownerWitnessed and recorded
Taxiway lighting electrical testConfirms the electrical condition of circuits and equipmentIncludes the tests below
Taxiway lighting insulation testChecks cable and equipment insulation, for example with a meggerValues per specification
Taxiway lighting continuity testConfirms the series circuit is continuous and correctly connectedRun before energising
Taxiway lighting test reportRecords all results, instruments used and the outcomeSigned and kept with the as-built record
Acceptable values and methods come from the applicable specification. Electrical tests do not replace photometry, which checks the optical performance of the same lights.

Taxiway Lighting Acceptance Test & Taxiway Lighting Test Report

The taxiway lighting acceptance test is the formal check of the installation against the specification, for acceptance by the owner. It is witnessed and recorded. The taxiway lighting test report then records all results, the instruments used and the outcome, and is signed and kept with the as-built record.

Taxiway Lighting Electrical Test

The taxiway lighting electrical test confirms the electrical condition of the circuits and equipment. It includes the insulation and continuity tests, and it does not replace photometry, which checks the optical performance of the same lights.

Taxiway Lighting Insulation Test

The taxiway lighting insulation test checks the insulation of cables and equipment, for example with a megger. Acceptable values come from the applicable specification.

Taxiway Lighting Continuity Test

The taxiway lighting continuity test confirms that the series circuit is continuous and correctly connected. It is run before the circuit is energised.

SERIES CIRCUIT · COMMISSIONING TESTS WHOLE LOOP · CCR ISOLATED 1 · ISOLATE 2 · LOOP Ω 3 · INSULATION 4 · ENERGISE ISOLATING TRANSFORMER + FIXTURE, ALL IN SERIES TXTXTXTX CCR ISOLATED LOCKED OFF OUTPUT DISCONNECTED LOW-RESISTANCE OHMMETER Ω INSULATION TESTER MΩ EARTH CLAMP AMMETER (ENERGISED STEP) SERIES LOOP (PRIMARY CABLE) LOOP RESISTANCEcompare with the design value INSULATION TO EARTHwhole loop, high and steady CURRENT AT EACH STEPstart on the lowest step NEVER OPEN A LIVE LOOPisolate and prove dead first SCHEMATIC · NOT TO SCALE · LIMITS COME FROM THE DESIGN, THE CCR DATA AND THE SPECIFICATION
Figure 8. A series circuit is proved as a whole loop, after its cables, connectors and transformers have been tested one by one. With the CCR isolated, the loop is checked for resistance and for insulation to earth, then brought up step by step while the current is read at each step.AGL Visual Encyclopedia: How is a series circuit tested before it is energised?
Diagnostics

Common Taxiway Lighting Faults

Tap a symptom to see possible causes.

One light OFF

Possible Cause

  • Fixture fault
  • Transformer fault
  • Connector or secondary connection

Multiple lights OFF

Possible Cause

  • Series circuit problem
  • Cable fault
  • CCR problem

Entire circuit OFF

Possible Cause

  • CCR fault
  • Control fault
  • Cable or protection fault

Low intensity

Possible Cause

  • Fixture degradation
  • Contamination
  • Electrical problem

Flickering

Possible Cause

  • Loose connector
  • Transformer fault
  • Fixture fault

Incorrect colour

Possible Cause

  • LED/module problem
  • Optical problem

Stop bar not operating correctly

Possible Cause

  • Fixture fault
  • Circuit fault
  • Control or switching logic

Good electrical test, poor light output

Possible Cause

  • Optical problem
  • Alignment problem
Troubleshooting

A Practical Troubleshooting Approach

Symptom: one taxiway light is dark. Work through the checks in sequence, and for multiple failures move the investigation upstream.

1

Is the series circuit operating?

Confirm the circuit itself is energized and carrying the correct current.

2

Is the isolation transformer healthy?

Check the transformer's primary and secondary performance.

3

Are the connectors secure?

Inspect primary and secondary connectors for resistance, heating or damage.

4

Is the fixture receiving the correct secondary supply?

Verify voltage/current reaching the fixture itself.

5

Is the fixture itself healthy?

Check the fixture's internal condition, LED/lamp and optics.

6

Verify after correction

Confirm operation and optical performance once the fault is corrected.

For multiple failures, investigation should move upstream toward: Fixture → Transformer → Connector → Cable → Series Circuit → CCR → Control.

FAULT-ISOLATION FLOWCHART · SYMPTOM, TYPE, SECTIONFIRSTTELL ATC · SWITCH OFF AND ISOLATE THE CCR · LOCK OFF · AUTHORISED PERSONNEL ONLYALL LIGHTS OUTCCR open-circuit alarm, no currentOPEN CIRCUITa break in the loopTEST CONTINUITY BY SECTIONFault is where it failsCCR TRIPSEarth-fault or overcurrent alarmEARTH FAULTinsulation to earth is lowTEST INSULATION RESISTANCE BY SECTIONLow reading marks the sectionSOME LIGHTS OUTCCR normal, circuit runningLOCAL FAULTfixture, connector or transformerCHECK THE DEVICE ITSELFLight, secondary connector, transformerNARROW DOWN BY HALF-SPLITTEST: GOOD · SET ASIDEBAD · SPLIT AGAINfault sectionTHEN1 Repair the faulty part2 Retest section and circuit3 Restore, run, confirm status4 Record results, tell ATC
Figure 9. Make the circuit safe, read the symptom at the CCR, then narrow the fault down section by section until one part remains.AGL Visual Encyclopedia: How is a fault isolated in a series circuit?
Failures

What Happens When Taxiway Lighting Fails?

Failures range from one lamp to a whole circuit, and the response depends on how much guidance is lost.

What Happens When Taxiway Lighting Fails?

The effect depends on how much is out. Isolated failures are managed within the aerodrome's serviceability limits. A larger failure, or one affecting a stop bar or a holding position, can restrict taxiing, require a NOTAM and call for follow-me or procedural control until it is restored.

Taxiway Light Not Working

A taxiway light not working may be a lamp, transformer, connector, cable or CCR problem. Fault finding starts from the circuit status and current. See the troubleshooting engine.

AAI Taxiway Lighting

The Airports Authority of India (AAI) operates a large share of Indian airports. AAI taxiway lighting is specified and maintained in line with ICAO Annex 14 as implemented through DGCA regulation and AAI's own technical specifications.

PLAN VIEW · A CLOSED BRANCH AND A BYPASSABLE UNSERVICEABLE AREA CLOSED MARKING · YELLOW CROSS CLOSED BRANCH · LIGHTS OFF UNSERVICEABILITY LIGHTS · FIXED RED UNSERVICEABLE AREA · BYPASS OPEN TAXIWAY IN USE · LIT CLOSED MARKINGYellow cross at each end of the closed part UNSERVICEABILITY LIGHTSFixed red across the entrance or round the area LIGHTS ON CLOSED PARTSwitched off, except for maintenance CLOSED = DO NOT ENTER · UNSERVICEABLE = KEEP CLEAR OF THIS AREA, BYPASS IS POSSIBLE
Figure 10. When part of the movement area cannot be used, the lighting has to say so. A closed taxiway goes dark and is marked, and an area aircraft must avoid is outlined with fixed red lights.AGL Visual Encyclopedia: What are closed taxiway and unserviceability lighting?
Maintenance

Taxiway Lighting Maintenance

A practical maintenance program covers four areas, moving beyond "replace the light when it fails" toward a structured inspect–measure–diagnose–correct–verify cycle.

Electrical

Check circuit, CCR, transformers, cables and connections.

Mechanical

Inspect fixture condition, mounting, seals and physical damage.

Optical

Inspect lenses, LEDs and optical assemblies.

Photometric

Measure lighting performance where required.

Inspect → Measure → Diagnose → Correct → Verify — not simply "replace the light when it fails."

Commissioning

Taxiway Lighting Commissioning Sequence

Installation
Visual Inspection
Position Verification
Electrical Testing
CCR Testing
Circuit Verification
Control & Monitoring
Photometry
Operational Verification
Final Documentation

The objective is to verify both the electrical system and the visual guidance function it provides to the pilot.

COMMISSIONING SEQUENCE · IN WHAT ORDER PASS · RECORD · HOLD · THEN THE NEXT STAGE 1 PRE-COMMISSION Installation checked Circuit tests done Records ready HOLD: ready to energize 2 ENERGIZATION Controlled switch-on Steps raised in turn Readings watched HOLD: stable on all steps 3 FUNCTIONAL Each light and control Steps and alarms Local and remote HOLD: works as designed 4 INTEGRATION Circuits run together Interlocks proven Fault behaviour HOLD: system agrees 5 ALCMS LINK Control signals Status feedback Failure handling HOLD: command = response 6 PAPI Aiming and settings Glide path angle Flight check if required HOLD: angles confirmed 7 SIGNS Legends correct Brightness steps Control and status HOLD: signs correct 8 ACCEPTANCE Records reviewed Key tests witnessed Certificate signed HOLD: owner accepts A STAGE FAILS CORRECT · RE-TEST · REPEAT ALL EIGHT PASSED READY FOR SERVICE SCHEMATIC · STEPS SHORTENED · NOT TO SCALE
Figure 11. The planned order for bringing an AGL system into service — each stage passed and recorded before the next begins.AGL Visual Encyclopedia: What is the commissioning sequence?
LED Technology

LED Taxiway Lighting

Potential Benefits

Long Service Life Reduced Energy Use Fewer Lamp Replacements Good Optical Efficiency Reduced Maintenance

LED fixtures still require proper electrical testing, mechanical inspection, optical inspection, alignment and photometric verification.

LED technology reduces some maintenance requirements but does not eliminate the need for inspection and measurement.

Principle & Design

Taxiway Lighting Working Principle, Functions, Design & Operations

Taxiway Lighting Working Principle

Taxiway lighting working principle: like the rest of AGL, taxiway lights run on series circuits fed by constant current regulators, each light on an isolating transformer. Circuits can be split so segments are switched separately.

Taxiway Lighting Functions

Taxiway lighting functions are to mark the edges and centreline of taxiways, guide aircraft between runway and apron, and mark holding positions and intersections so pilots stay on the correct route.

Taxiway Lighting Design

Taxiway lighting design covers edge and centreline layout, spacing (closer on curves), colour, circuit split for selective switching, stop bar and guard light integration, and the control interface.

Taxiway Lighting at Different Airports

Taxiway lighting for airports ranges from edge lights alone at small aerodromes to centreline, stop bar and guidance systems at large airports with low-visibility operations. Choose the level the operations and standards demand.

Taxiway Lighting Operations

Taxiway lighting operations cover switching circuits, selecting intensity and, where installed, switching centreline segments or stop bars on and off to guide aircraft, normally from the tower through the ALCMS.

Taxiway Lighting Selection Guide

Taxiway lighting selection guide: decide edge or centreline guidance from operations and visibility, then choose elevated or inset fixtures, LED or halogen sources and colours that meet the standard.

Taxiway Lighting Technical Guide

Taxiway lighting technical guide: use this page with the aerodrome layout, circuit drawings and manufacturer data to check positions, colours, spacing and electrical details.

TAXIWAY WORKING · CLOSED, SEPARATED, CHECKED 1 CLOSESection closed, barriers set 2 CLEARANCEContact kept throughout 3 WORK SAFELYInside area, clear of aircraft 4 REOPENInspect, restore, report PLAN VIEW · CLOSED TAXIWAY SECTION BESIDE AN ACTIVE TAXIWAY ACTIVE TAXIWAY · AIRCRAFT HAVE PRIORITY KEEP CLEAR OF WINGTIPS & JET BLAST BARRIER · CLOSED BARRIER · CLOSED WORK AREA · LIGHT UNDER WORK ATC / AIRPORT OPS CLEARANCE · CONTACT KEPT INSPECT · LIGHTS CHECKED · BARRIERS LIFTED ON CLEARANCE 1234 SCHEMATIC · THE SECTION STAYS CLOSED UNTIL ATC IS TOLD THE AREA IS CLEAR
Figure 12. Working on a taxiway section while aircraft move nearby: what is closed, how people stay clear and what must happen before it reopens.AGL Visual Encyclopedia: What is taxiway working?
Edge & Centreline

Taxiway Edge Lights, Centreline Lighting Requirements & Fixture Types

Taxiway Edge Lights Working Principle

Taxiway edge lights working principle: each blue fixture is fed by an isolating transformer on the series circuit, so a failed lamp does not break the loop, and brightness follows the CCR step.

Taxiway Edge Lights Types

Taxiway edge lights types are elevated fixtures on frangible couplings, and inset fixtures where elevated lights would be a hazard or obstruction, in LED or halogen versions.

Taxiway Edge Lights Functions

Taxiway edge lights functions are to show the lateral limits of the taxiway, especially on curves and intersections, so aircraft stay on the paved surface at night.

Taxiway Edge Lights Components

Taxiway edge lights components are the blue lens, light source, fixture body, frangible coupling or inset housing, isolating transformer, base and connectors.

Taxiway Centreline Lighting Requirements

Taxiway centreline lighting requirements come from ICAO Annex 14 and national rules: green lights along the taxiway centreline, spaced closer on curves, provided where operations in low visibility or complex layouts call for them.

Why Taxiway Lights Are Blue and Green

Taxiway lights blue and green: blue marks the taxiway edges and green marks the centreline. The colour difference lets pilots tell taxiway guidance from runway lighting.

Taxiway Light Fixture Types

Taxiway light fixture types include elevated edge lights, inset centreline lights, stop bar lights, guard lights, and illuminated signs. Each has its own colour, beam pattern and mounting.

SECTIONS · FOUR TAXIWAY FIXTURES ELEVATED EDGE edge of the taxiway marks the taxiway edges blue, seen from all around raised on a frangible coupling INSET CENTRELINE taxiway centreline marks the taxiway route green, one or both ways flush, takes wheel loads INSET STOP BAR across the taxiway marks the holding position red, faces the aircraft flush, takes wheel loads RUNWAY GUARD before the runway warns of the runway ahead yellow, flashes in pairs raised beside the taxiway
Figure 13. Edge, centreline, stop bar and runway guard: four taxiway lights that differ in what they mark, how they are mounted, their colour and how they operate.AGL Visual Encyclopedia: Different taxiway fixtures
Holding & Standards

Holding Position Lights, Rapid Exit Lighting, Signs, ICAO Requirements & Testing

Taxiway Holding Position Lights

Taxiway holding position lights include red stop bars, flashing yellow runway guard lights and intermediate holding position lights. They mark where aircraft must stop and are controlled from the tower.

Taxiway Rapid Exit Lighting

Taxiway rapid exit lighting guides aircraft off the runway at higher speed, using green centreline lights on the exit and yellow rapid exit taxiway indicator lights that show how far the exit is.

Information Signs on Taxiways

Information signs on taxiways show location and direction: direction and destination signs are yellow with black inscription, and location signs are black with yellow inscription. Signs must be lit or reflective as required.

ICAO Requirements for Taxiway Lighting

Taxiway lighting ICAO requirements are in Annex 14 Volume I, Chapter 5, covering taxiway edge, centreline, stop bar and holding position lights, with their colour, intensity and spacing. Check the current edition.

Taxiway Lighting Testing Procedure

Taxiway lighting testing procedure covers insulation and continuity tests, current at every step, aim and colour checks, and control tests for stop bars and selectively switched circuits, with results recorded.

Taxiway Lighting Preventive Maintenance

Taxiway lighting preventive maintenance is a scheduled routine of cleaning, inspection, electrical tests and replacement of worn parts, with extra attention to inset lights on busy taxiways.

RAPID EXIT TAXIWAY (RET) DIRECTION OF LANDING ROLL RUNWAY EDGE (SECONDARY) 3 2 1 RET INDICATOR LIGHTS (RETILs) PERPENDICULAR STACKS, EXIT SIDE · 3-2-1 RUNWAY HOLDING POSITION MARKING TAXIWAY CENTRE LINE ON THE RET SOLID GREEN BEYOND THE PROTECTED AREA ALTERNATE GREEN/YELLOW FIRST GREEN · LAST YELLOW NORMAL TAXI SPEED REACHED RUNWAY SCHEMATIC VIEW OF A RAPID EXIT TAXIWAY · SPACING, ANGLE, AND CURVE SHAPE ILLUSTRATIVE · NOT TO SCALE
Figure 14. A two-part lighting system that helps a landing aircraft find and take a high-speed turn-off without slowing to normal taxi speed first — yellow indicator lights on the runway give distance-to-go, then green centre line lights guide the aircraft through the curved exit itself.AGL Visual Encyclopedia: What is rapid-exit taxiway lighting?
Design Considerations

Engineering Checklist

A practical way to track a taxiway lighting project from design through commissioning. Click any item to mark it complete.

Design

Taxiway geometry reviewed
Applicable lighting requirements identified
Edge lighting planned
Centreline lighting planned where required
Stop bars identified
Runway guard lights identified
Signs coordinated
Circuits, CCR capacity & transformers checked
0 / 8 complete

Installation

Fixture locations verified
Alignment checked
Transformers installed correctly
Connectors installed correctly
Cable identification completed
Signs correctly positioned
0 / 6 complete

Testing

Insulation resistance
Continuity
Transformer testing
Connector inspection
CCR testing
Series-circuit current
Control & monitoring verification
0 / 7 complete

Photometry & Commissioning

Intensity & distribution
Colour & alignment
Operational test
Intensity-step test
Stop bar operation
Fault monitoring & final documentation
0 / 6 complete
Documentation

Taxiway Lighting Project Documentation

Lighting Layout Series-Circuit Drawings Single-Line Diagrams Cable Schedule Transformer Schedule Fixture Schedule CCR Schedule Sign Schedule Control Schematic BOQ Technical Specifications Electrical Test Reports Photometry Reports Commissioning Records As-Built Drawings Maintenance Records
Test Yourself

Quick Knowledge Check

Q1. What is the primary purpose of taxiway centreline lighting?

A. Illuminating the full pavement surface
B. Marking the lateral boundary of the taxiway
C. Providing directional guidance along the intended taxi path
D. Warning of a runway holding position

Q2. A stop bar is best described as:

A. Just another taxiway edge light
B. Part of the operational control and runway-incursion prevention system
C. A decorative lighting element
D. A photometric test point

Q3. Why can a taxiway fixture "pass" a visual check but still be underperforming?

A. Because a light being ON does not confirm correct intensity, distribution or alignment — only photometry does
B. Because visual checks are more accurate than photometry
C. Because LED fixtures never need photometric verification
D. Because taxiway fixtures don't require electrical testing
Explore More

Explore More AGL Engineering

FOUNDATION

AGL Fundamentals

Build your understanding of the complete Airfield Ground Lighting system.

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ENGINEERING

AGL Design & Electrical Engineering

Layout, series circuits, CCR sizing, transformers, cable design and control.

Open AGL Design →
PERFORMANCE

AGL Photometry

Verify the optical performance of the installed system.

Open AGL Photometry →
DIAGNOSTICS

AGL Troubleshooting Engine

Diagnose taxiway lighting electrical, optical and control problems.

Open the Troubleshooting Engine →
INTEGRATION

Airfield Markings & Signage Integration

Coordinate taxiway lighting with markings and signage into one visual guidance system.

Open Markings & Signage Integration →
APRON

Apron Lighting & Stand Guidance

Extend taxiway guidance principles into apron and aircraft stand lighting.

Open Apron Lighting →
SAFEGUARD

Runway Guard Lights & Stop Bars

The incursion-prevention lighting integrated into the taxiway network.

Open Guard Lights & Stop Bars →
SAFETY

Runway Incursion Prevention & SMGCS

The broader surface movement guidance system taxiway lighting supports.

Open SMGCS →
INFORMATION

Airfield Signage & Taxiway Guidance Signs

The signage layer paired with taxiway lighting.

Open Airfield Signage →
CONTROL

ALCMS

The control system that switches and monitors taxiway circuits.

Open ALCMS →

Guide the Aircraft. Protect the Runway.

From taxiway geometry to energized circuit, from electrical testing to photometric verification — explore the complete AGL knowledge base for taxiway lighting engineering.

Explore the Knowledge Hub AGL Design Services
Keyword Reference

LED Taxiway Lights

LED taxiway lights

LED taxiway lights replace halogen lamps in edge and centreline fixtures to cut energy use and maintenance. They must still meet the same colour, intensity and distribution requirements, and they must work properly with the CCR and series circuit. Check the manufacturer's data and test the installed lights.

AGL Engineering Hub

Explore the AGL Engineering Knowledge Hub

Fundamentals

All About AGL How Airfield Lighting Works Physics of AGL AGL Components Airfield Lighting Colour Codes LED Airfield Ground Lighting LED Benefits, Lifespan & Energy Savings Solar AGL (SAGL) Portable AGL (PAGL) Advantages & Disadvantages by System Type Sustainability in AGL

Standards & Compliance

ICAO Annex 14 AGL Requirements ICAO Aerodrome Lighting Requirements FAA AC 150/5340 Series EASA CS-ADR-DSN Compliance NOTAMs

Runway, Taxiway & Approach Lighting

Runway Lighting Systems Taxiway Lighting Systems Airport Approach Lighting Systems Approach Lighting Systems Apron Lighting & Stand Guidance Apron Floodlighting Design & Lux Levels VDGS: Visual Docking Guidance Obstruction Lighting & Marking Airfield Signage & Guidance Signs Markings & Signage Integration

Surface Movement & Safety

Follow the Greens Runway Guard Lights & Stop Bars Runway Incursion Prevention & SMGCS A-SMGCS ALCMS

PAPI

How Does PAPI Work? PAPI Engineering Guide ICAO PAPI Requirements PAPI Installation & Aiming PAPI Calibration & Alignment PAPI Alignment & Maintenance PAPI Maintenance Checklist

Electrical Engineering & Power

AGL Design & Electrical Engineering Diagrams, Schematics & Wiring CCR Working Principle CCR Deep Dive AGL Isolating Transformers Airport Isolating Transformer Junction Box & Transformer Housing Cables & Connector Engineering Electrical Architecture & Redundancy Emergency Backup Power Emergency Power & Lighting Systems Surge Protection & Lightning Mitigation Lightning & Surge Protection for Circuits

Photometry & Testing

AGL Photometry Photometric Testing Guide Photometric Testing Procedure Runway Lighting Photometry Taxiway Lighting Photometry AGL Testing & Inspection Installation & Commissioning Testing & Commissioning Guide

Maintenance, Inspection & Safety

Preventive & Corrective Maintenance Maintenance Schedule & Checklist Inspection, Maintenance & Audit Checklists How to Inspect & Replace Airfield Lights Common Failure Causes & Fixes Outage Response & Runway Closure Maintenance Work Safety: LOTO, Permits, PPE

Resources, Documentation & Careers

Datasheets, Catalogues & PDF Guides Project Documentation: ITP, As-Built, O&M Engineer & Technician Job Description / Salary
FAQ

Frequently Asked Questions

Q1What is a taxiway lighting system?

It is the coordinated arrangement of visual aids used to identify taxiways, provide directional guidance and assist aircraft movement on the aerodrome surface. It may include taxiway edge and centreline lights, stop bars, runway guard lights, centreline lead-on and lead-off lights, and illuminated signs, depending on layout, operations, visibility and standards.

Q2Why is taxiway lighting important?

Once an aircraft leaves the runway, pilots still need continuous visual information to navigate the surface. Taxiway lighting helps them understand where the taxiway and its edges are, which direction to follow, where it meets a runway, where they must stop and which route to take.

Q3What are the main taxiway lighting elements?

Taxiway edge lights identify lateral boundaries, centreline lights guide along the intended taxi path, lead-on lights guide from one route toward another, lead-off lights help aircraft leave a runway onto a taxiway, stop bars give a controlled stopping point, and runway guard lights add warning at holding positions.

Q4What is the difference between lead-on and lead-off lighting?

Centreline lead-on lighting guides an aircraft from one taxiway route toward another operational route. Lead-off lighting assists aircraft leaving a runway and transitioning onto a taxiway, creating a visual connection from runway to runway exit to taxiway.

Q5How do stop bars and runway guard lights work at a holding position?

The taxiway centreline leads to the stop bar, with runway guard lights flanking the holding position just before the runway edge. They work together with taxiway centreline and control logic, and an aircraft should not cross an illuminated stop bar without ATC clearance.

Q6Why is stop bar design coordinated with other systems?

A stop bar's design must be coordinated with taxiway centreline lighting, runway protection, the control system, ATC operational procedures, monitoring and switching logic. It is part of runway-incursion prevention, not just another taxiway light.

Q7How is runway guard lighting different from taxiway edge lighting?

Runway guard lighting serves a fundamentally different purpose: it exists specifically to draw pilot attention to the holding position, and may use elevated fixtures, inset fixtures or other configurations depending on the system.

Q8What do taxiway lighting colours mean?

Colour is part of the visual coding system, and different colours may identify different functions or locations. Colour selection should always be based on the specific lighting function and applicable ICAO, FAA, national and project requirements.

Q9Does a taxiway light being ON mean it is working correctly?

No. A light being on does not automatically mean it is performing correctly. Electrical testing, inspection and photometry confirm actual performance.

Q10What is the electrical chain behind taxiway lighting?

A simplified chain runs from the airport power supply and AGL control system through the CCR, series circuit and isolation transformers to the taxiway light fixtures, their optical output and the pilot's visual guidance. Systems with stop-bar switching or route-based centreline selection may add dedicated control, switching and monitoring interfaces.

Q11What happens when taxiway lighting fails?

The effect depends on how much of the lighting is out. Isolated failures are managed within the aerodrome's serviceability limits. A larger failure, or one that affects a stop bar or holding position, can restrict taxiing, require a NOTAM and call for procedural control until the lighting is restored.

Q12What is the difference between runway edge and taxiway edge lights?

Runway edge lights are white, turning yellow near the end of an instrument runway, and mark the limits of the runway. Taxiway edge lights are blue and mark the limits of the taxiway. They also differ in typical intensity and in the standards that apply, so the colour tells the pilot which surface they are on.

Q13What is the difference between runway centerline and taxiway centerline lights?

Runway centerline lights are white, then alternate red and white, then red toward the runway end. Taxiway centerline lights are green, with alternating green and yellow (first light green, last light yellow) where the line lies inside the ILS/MLS critical or sensitive area on a runway exit. The different colours let the pilot recognise the surface.

Q14What color are taxiway edge lights?

Taxiway edge lights are blue. They are omnidirectional fixtures that mark the edges of the taxiway.

Q15What is the taxiway centerline color?

The taxiway centerline color is green. Where the centreline lies inside the ILS/MLS critical or sensitive area on a runway exit, the lights alternate green and yellow, starting with green and ending with yellow.

Q16What are the stop bar light colors?

Stop bar lights are red and are shown toward the aircraft approaching the holding position. They are switched on to stop traffic and off to allow it to proceed.

Q17What are the runway guard light colors?

Runway guard lights are yellow. They flash alternately, either as a pair of elevated lights beside the taxiway or as a row of in-pavement lights across it, to warn of an approaching runway holding position.

Field Insight

Engineering & Expert Notes

RS
By Rahul Sharma
Airfield Ground Lighting Specialist
Layout Follows Operational Use
Layout

Check that edge, centreline and guidance elements match the operations.

Understand Circuit Segmentation
Electrical

Know which sections can be switched independently and how that affects control.

Test the Control Interface
Control

Verify selection and intensity from the control point.

Pay Attention to Holding Positions and Stop Bars
Hold Points

Check consistency among lights, signs and markings.

Verify Photometry and Colour
Photometry

Measure where required and keep records.

Maintain Records of Changes
Records

Update drawings and registers when layout changes.

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