Taxiway & Standard
Straight and curve maximum spacing are kept in separate databases per standard — never one universal value.
Changing the input unit converts the values already typed (lengths, spacings, offsets, segment list and coordinates); angles are unchanged.
Used for inner/outer curve-edge geometry: Redge = RCL ± (W/2 + D), where D is the edge-light offset entered below (taken as 0 if blank).
Documentation only — does not alter the spacing engine in this calculator.
Rule note
"One side" counts Side A only. "Project-specific" is currently counted as both sides and flagged for review — adjust manually. ICAO Annex 14 (5.3.18.1) requires edge lights on night-use taxiways that have no centreline lights; where centreline lights are provided, edge lights are a project decision. Verify against the approved layout.
Spacing Criteria
ICAO — straight-section maximum spacing is 60 m, applied automatically below.
Nominal spacing used to generate curve positions along the arc.
Rule note
Neither ICAO nor FAA curve-spacing tables are hard-coded here — this calculator will not silently reuse the straight-section value on a curve. Enter the applicable figure or the curve check is skipped.
Edge-Light Lateral Offset
Rule note
Runway edge-offset values (Calculator #07) are not assumed to apply identically to taxiways — enter the applicable ICAO/FAA taxiway range for this project to validate against.
Taxiway Geometry — Segments
One segment per line, in order along the taxiway: straight,<length> · curve,<centreline radius>,<angle deg> · intersection,<length> · holding,<length> · stopbar,<length> · other,<length>,<note>. Exclusion types (intersection/holding/stopbar/other) consume chainage but generate no edge lights.
Default example reproduces the worked 1,240 m taxiway (S1–S3 straight, C1–C2 curves) from the design brief.
Duplicate-Position Handling
Rule note
Full 2D collision detection across intersecting taxiways is outside this segment-based engine's scope. Where a generated position coincides with a fixture already counted on a crossing taxiway (e.g. Calculator run for another leg), enter the count here so Qtotal = ΣQi − Qduplicates — do not assume the software has detected it automatically.
Report details
Segment schedule
Segment Schedule
Segment-level quantity, not a single-length division — Qtotal = ΣQi − Qduplicates. Curve segments report inner-edge and outer-edge positions separately since they follow different radii and arc lengths.
Quantity summary
Quantity Summary
| Component | Basis | Quantity |
|---|---|---|
| Side A (edge 1) | Straight-side + inner-curve positions | — |
| Side B (edge 2) | Straight-side + outer-curve positions | — |
| Duplicate positions removed | Manual entry | — |
| Total physical fixtures | — |
Where a curve reverses direction, the physical left/right mapping of "Side A" and "Side B" may not stay consistent along the taxiway — confirm against the approved layout drawing before using this split for procurement.
Build-up
Check measured fixture positions against Smax. The standard, units and spacing limits come from the Calculate tab.
Existing-Installation Inspection (optional — coordinate mode)
How This Calculator Works
Taxiway geometry is broken into a sequence of straight and curve segments plus exclusion zones (intersections, holding positions, stop bars) rather than calculated as one overall length — each segment gets its own rule, and the results are summed.
Straight-section rule
ICAO taxiway-edge-light spacing on straight sections is taken as not exceeding 60 m per ICAO Annex 14, Volume I, Chapter 5 (taxiway edge lights, straight sections). The FAA equivalent (200 ft per AC 150/5340-30J) is held as a separate editable value so the two standards are never silently merged into one value.
Curve geometry — arc length
Worked example: R = 100 m, θ = 90° → Larc = 2π(100) × (90/360) = 157.08 m. The calculator applies the curve-specific spacing rule to this arc length rather than treating it as a 157 m straight section.
Inner and outer curve radius
Worked example: RCL = 100 m, W = 23 m, D = 0 → Rinner = 88.5 m, Router = 111.5 m (with D = 0.6 m: 87.9 m and 112.1 m, because the lights sit outside the pavement edge). Each edge follows its own radius and therefore its own arc length and light count — a curve segment is calculated as two related but distinct edges, not one shared count halved.
Intersection, holding-position & stop-bar handling
These are not taxiway edge lights. Segments tagged as an intersection, holding position, stop bar, or other exclusion consume chainage but are excluded from the edge-light count entirely and generate a review flag rather than being silently skipped — "Taxiway edge-light calculation terminates/interacts with this configuration — detailed layout review required."
Duplicate-fixture control
Where two generated positions from crossing taxiways would occupy the same physical location, this calculator does not attempt automatic 2D collision detection — that requires a full site coordinate model outside a segment-based engine. Instead it exposes a manual "duplicate positions removed" figure so Qtotal = ΣQi − Qduplicates is never silently double-counted, and flags the assumption openly rather than hiding it.
Existing-installation inspection
Straight-line Euclidean distance between consecutive measured fixtures, checked against the selected Smax (straight or curve). This formula works identically on straight or curved runs — only the applicable criterion differs, which is why the calculator asks which one applies to each entered coordinate set.
Standard-specific spacing database
| Standard | Straight | Curve |
|---|---|---|
| ICAO Annex 14 | 60 m | Project-entered |
| FAA AC 150/5340-30J | 200 ft (60.96 m) | Project-entered |
The ICAO (60 m) and FAA (200 ft) straight-section maxima are pre-filled as editable defaults. Curve spacing depends on radius and is left project-entered — the radius-based ICAO/FAA curve tables are not incorporated yet.
Straight-section worked example
| L | S | N | Positions/side | Total (both sides) |
|---|---|---|---|---|
| 600 m | 60 m | 10 | 11 | 22 |
Positions per side are generated from the actual station count, not assumed as N + 1 by formula alone. A fixture at the joint between two lit segments is counted once.
Segment-level quantity
Calculating each segment independently and summing is more reliable than treating the entire taxiway as one length, since straight and curve sections — and exclusion zones — follow different rules.
What this calculator does not do
It does not perform true 2D intersection geometry between two taxiways, does not maintain the radius-based ICAO/FAA curve-spacing tables, and does not generate fixture x,y coordinates (no taxiway bearing/orientation input is collected). Arc length, inner/outer radius, and segment-level quantity are calculated; exact figure-level geometry at intersections must be confirmed against the approved layout.
Taxiway Edge Lights: Frequently Asked Questions
Quick answers on how the calculator sizes taxiway edge lighting.
What does the Taxiway Edge Light Spacing & Quantity calculator do?
It breaks a taxiway into straight and curve segments plus exclusion zones, calculates each on its own spacing rule, and sums the edge-light quantity. It also checks edge-light offset and can check measured fixture coordinates on an existing installation against the maximum spacing.
Why not just divide the taxiway length by the spacing?
Taxiway geometry has curves, intersections, fillets and holding positions that a single-length division cannot represent. The calculator works segment by segment, so Q_total = ΣQ_i − Q_duplicates, and each segment follows the rule that applies to it.
How is the straight-section spacing calculated?
N = ⌈L ÷ S_design⌉ intervals, then S_actual = L ÷ N, which must not exceed S_max. The maximum is 60 m for ICAO Annex 14 and 200 ft (60.96 m) for FAA AC 150/5340-30J. Both are pre-filled as editable defaults, so confirm them against the project specification.
How are curves handled?
Each curve has an inner and an outer edge with its own radius: R_inner = R_CL − (W/2 + D) and R_outer = R_CL + (W/2 + D), where D is the edge-light offset. The arc length is L_arc = R × θ. For R_CL = 100 m, W = 23 m and D = 0, the radii are 88.5 m and 111.5 m. Each edge gets its own light count, not one shared count halved.
Are the curve spacing limits built in?
No. Curve spacing depends on radius, and the ICAO and FAA curve tables are not hard-coded. You enter the curve maximum spacing from the applicable table or the project specification. If it is left blank, the curve check is skipped, and the calculator never reuses the straight-section value on a curve.
What happens at intersections, holding positions and stop bars?
Segments tagged as an intersection, holding position, stop bar or other exclusion use up chainage but generate no edge lights. Each one raises a review flag, because the detailed layout there must be confirmed against the approved drawing.
How are duplicate fixtures at crossing taxiways handled?
The calculator does not do full 2D collision detection between taxiways. Where a position coincides with a fixture already counted on a crossing taxiway, you enter the number of duplicates removed so the total is not double-counted.
Is the result a final bill of quantities figure?
No. It is a quantity generated from the selected standard and the geometry you enter. Final locations at intersections, curves, holding positions, stop bars and other special areas must be verified against the approved aerodrome lighting layout.