Runway Edge VS Taxiway Edge
Two Boundary-Marking Systems, Two Different Jobs — runway edge lights define the usable lateral limits of the runway for take-off and landing, while taxiway edge lights define the lateral limits of the taxiway and help the pilot follow the taxiway route during ground movement. The clearest distinction between them is colour, photometric performance and installation requirements.
At a Glance
| Feature | Runway Edge Light | Taxiway Edge Light |
|---|---|---|
| Main purpose | Defines runway edges | Defines taxiway edges |
| Primary operation | Take-off / landing | Taxiing |
| Typical colour | White | Blue |
| Location | Along runway edges | Along taxiway edges |
| Pilot guidance | Runway width/boundary | Taxiway boundary |
| Typical fixture | Elevated or inset | Usually elevated or inset |
| Low-visibility role | High | High |
| Intensity requirement | Generally higher | Generally lower |
| Aircraft speed | Higher | Lower |
| Centreline relationship | Used with runway centreline lights where applicable | Used with taxiway centreline lights where applicable |
What Is a Runway Edge & Taxiway Edge Light?
Runway Edge Light
Installed along both sides of the runway to show the pilot the lateral limits of the runway.
Provides visual reference for
- Take-off
- Landing
- Runway alignment
- Runway width
- Runway limits
Taxiway Edge Light
Installed along the edges of taxiways to show the lateral limits of the taxiway during ground movement.
Provides visual reference for
- Taxiing
- Taxiway boundaries
- Curves and turns
- Taxiway identification
Runway Edge = White · Taxiway Edge = Blue
This is the fastest way to tell the two systems apart, day or night, and it is the first thing every AGL engineer memorises.
There are specific colour changes near the runway end for certain runway configurations. Taxiway edge remains blue throughout, which gives the pilot an immediate visual distinction between runway and taxiway boundaries.
Why Different Colours?
At night: the colour difference is what lets a pilot instantly identify whether a visible boundary belongs to the runway (white) or the taxiway (blue) — without needing to consult a chart or wait for further confirmation.
What Each System Is Guiding
Runway Edge Light
Runway lighting is designed for aircraft operating at higher speeds and demanding visibility conditions, so runway edge lights guide take-off, landing and runway alignment.
Taxiway Edge Light
Taxiway edge lights are primarily ground-movement guidance — for boundaries, curves and turns — rather than high-speed runway guidance.
Intensity Requirements
Runway edge lights may have higher intensity requirements than typical taxiway edge lights, since runway lighting supports higher-speed operations and demanding visibility conditions. The actual intensity depends on runway classification, operating conditions, runway type, lighting system and applicable ICAO/FAA requirements.
Taxiway edge lights are generally lower-intensity systems because the aircraft is moving at much lower speeds — their purpose is ground movement guidance rather than high-speed runway guidance.
Elevated & Inset Installation
Both systems can use elevated fixtures where permitted, and both runway and taxiway edge lights can use inset fixtures in appropriate locations — useful where elevated equipment could interfere with aircraft or ground vehicles. However, the fixture characteristics, frangibility, photometry and location requirements differ between the two systems.
| Installation | Runway Edge | Taxiway Edge |
|---|---|---|
| Elevated fixture | Where permitted | Where permitted |
| Inset fixture | Where appropriate | Where appropriate |
| Fixture characteristics | Runway-specific | Taxiway-specific |
| Frangibility, photometry, location | Governed by runway requirements | Governed by taxiway requirements |
Relationship With Centreline Lights
This is an important distinction. A runway edge system may be paired with runway centreline lights where applicable, while a taxiway edge system may be paired with taxiway centreline lights. Taxiway centreline lights, where provided, use a different colour and function from runway centreline lights.
Runway Edge vs Taxiway Edge
| Parameter | Runway Edge Light | Taxiway Edge Light |
|---|---|---|
| Area | Runway | Taxiway |
| Main operation | Take-off / landing | Taxiing |
| Standard colour | White | Blue |
| Boundary identified | Runway edge | Taxiway edge |
| Aircraft speed | High | Lower |
| Typical intensity | Higher | Lower |
| Centreline system | Runway centreline | Taxiway centreline |
| End/threshold colour coding | Yes, where applicable | Different taxiway guidance scheme |
| Fixture type | Elevated/inset | Elevated/inset |
| Low visibility | Important | Important |
| Main objective | Runway boundary | Taxi route boundary |
Circuit Arrangement
Both are commonly supplied through an AGL series circuit.
Simplified path: CCR → series circuit → isolation transformer → light unit (runway edge light or taxiway edge light). The actual circuit design depends on the airport's AGL system and applicable specification.
Maintenance Comparison
Runway Edge
- Light output
- Lens condition
- Alignment
- Fixture damage
- Frangibility
- Isolation transformer
- Cable condition
- Photometric performance
Taxiway Edge
- Blue light output
- Lens condition
- Fixture condition
- Alignment
- Frangibility
- Isolation transformer
- Cable condition
- Photometric performance
The maintenance principles are similar, but the photometric and operational requirements differ.
Common AGL Terminology Confusion
They are different systems. Taxiway edge lights are blue and mark the boundary of the taxiway. Taxiway centreline lights are normally green and guide the aircraft along the taxi route itself.
Runway edge lights are normally white; taxiway edge lights are normally blue. This colour separation is one of the most important concepts in airport ground lighting.
Taxiway edge lights are generally lower-intensity systems, since aircraft move at much lower speeds during taxiing than during take-off or landing.
Runway Edge Light vs Taxiway Edge Light
Runway edge and taxiway edge lights are not interchangeable systems. The fundamental difference is function, colour, photometric performance and installation requirements.
Runway edge lighting helps define the runway for take-off and landing, while taxiway edge lighting provides visual boundary guidance during aircraft ground movement.
Easy memory: Runway edge = white, taxiway edge = blue, taxiway centreline = green.
Engineering & Expert Notes
Verify Colour and Intensity for Each
PhotometryCheck against the right requirement.
Test Brightness Steps
ControlCheck the controls.
Do Not Mix Spares
SparesKeep types separate.
Inspect at Night
InspectionConfirm the pattern.
Frequently Asked Questions
Colour and function — runway edge lights are white and define the runway boundary for take-off and landing, while taxiway edge lights are blue and define the taxiway boundary for ground movement.
No. Taxiway edge lights are normally blue and mark the taxiway boundary. Taxiway centreline lights are normally green and guide the aircraft along the taxi route.
Runway lighting is designed for aircraft operating at higher speeds and more demanding visibility conditions, so runway edge lights generally need higher intensity than taxiway edge lights, which guide much slower ground movement.
Yes, both can use inset fixtures in appropriate locations, though the fixture characteristics, frangibility, photometry and location requirements differ between the two systems.
Both are commonly supplied through an AGL series circuit via a CCR and isolation transformer, though the actual circuit design depends on the airport's AGL system and applicable specification.
There are specific colour changes near the runway end for certain runway configurations. Taxiway edge lighting uses a different guidance scheme rather than this end/threshold colour coding.
Runway edge lights are normally white and mark the runway boundary for take-off and landing, with higher intensity. Taxiway edge lights are blue and mark the taxiway boundary for slower ground movement, with lower intensity. They are usually supplied from separate series circuits.
Governing Documents
For an actual project design, always verify the current edition of the applicable documents.
FAA AC 150/5340-30
Design and Installation Details for Airport Visual Aids — runway and taxiway edge lighting configuration, installation, photometric requirements and electrical systems.
ICAO Annex 14, Volume I
Aerodrome Design and Operations — runway and taxiway edge lighting colour, siting, intensity and operational requirements.
DGCA / AAI Requirements
For Indian airport projects, also verify applicable DGCA requirements, AAI requirements, airport-specific technical specifications, project drawings and contract specifications.
Final Engineering Note
Do not design a runway or taxiway edge lighting system from a generic web diagram. The final installation drawing should always be developed from the current governing standard, approved airport design and project-specific requirements.
Runway edge = white, defines runway limits. Taxiway edge = blue, defines taxiway limits. Taxiway centreline = green — a different system entirely.
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