Runway Strip / Threshold Geometry Checker

It is a checker, not a quantity tool. It turns your runway, displaced threshold and light row inputs into real positions along the runway, draws them, and tests each against the limits you set. It gives a pass, review or fail on edge offsets, the threshold and runway-end arrangement, and strip clearances, so errors are caught before the drawing is issued.

You enter the runway length and width, the design standard (ICAO Annex 14 or FAA AC 150/5340-30J), the runway operation, the strip dimensions, the displaced thresholds, the edge-light rows, and the threshold and runway-end rows for each end. The outputs are a plan view, a positions table, a layout SVG, a layout PNG and a check report CSV. You can work in metres or feet.

Pass means the entered value is inside the limit. Review means it is outside the usual arrangement or a limit is not set, and needs a drawing check. Fail means it breaks a limit you have set.

The number of intervals is the runway length divided by the design spacing, rounded up, and the actual pitch is the length divided by that number, so the actual pitch never exceeds the design spacing. The tool checks the actual pitch against the maximum, each row's offset from the runway edge against the maximum offset, that the two rows are equidistant from the centreline, and that both lie inside the strip.

The required number of threshold lights is the edge-row span divided by the pitch, rounded up, plus an endpoint adjustment, where the span is the runway width plus the two edge-light offsets. For precision runways the threshold row must carry at least that many lights at no more than the maximum pitch and reach the edge-light rows. For other runways the fixed minimum applies. The exact count is figure-dependent, so confirm it against the standard's figure. The end row needs the minimum count, must lie between the edge rows, and must sit within the allowed distance beyond the runway end.

With a displacement, the threshold row moves along the runway by that distance from the start end, or measured back from the far end. The landing distance becomes the runway length minus the displacement. Threshold and end lights are then separate rows by default, so fixture sharing no longer applies, and the edge lights between the runway end and the threshold show red in the approach direction.

The ICAO defaults are an edge spacing of up to 60 m on instrument runways and up to 100 m on non-instrument runways, an edge row offset of up to 3 m outside the runway edge, a threshold row up to 3 m outside the threshold, and a runway-end row of at least 6 lights up to 3 m outside the end. The yellow edge-light zone is the lesser of 600 m or one third of the runway length. FAA defaults use 200 ft edge spacing and 10 ft offsets. Every value is editable, and you should confirm each against the current edition of the standard and the approved project layout.

It does not check wing-bar lights, runway centreline or touchdown-zone lights, markings, stopways or clearways, or obstacle limitation surfaces. Strip dimensions are entered, not derived. It is a design-review aid and does not replace the approved lighting layout or the governing standard. For an installed runway, enter surveyed values.