Intermediate Holding Position Fixture

An Intermediate Holding Position Fixture is a complete assembly of lighting elements and mounting hardware designed to clearly mark intermediate holding positions on taxiways. This fixture typically includes a row of yellow/amber lights, frangible mounting bases, isolating transformers, and cable connections, providing a ready-to-install solution for defining holding boundaries at non-runway intersections and critical areas. Unlike individual lights, the fixture is a pre-assembled unit that ensures consistent spacing, alignment, and electrical connectivity, reducing installation time and improving reliability. The fixture is designed to withstand the harsh airfield environment while providing clear visual guidance to pilots and ground vehicle drivers.

This fixture exists to give an intermediate holding point — a taxiway crossing or entry to a critical area away from any runway — a complete, consistent lighting installation rather than a collection of individually sourced and field-assembled components. Because holding position accuracy directly affects how safely ground traffic is sequenced through that intersection, having every light, transformer, and mounting element pre-matched to the same specification removes the variability that could come from mixing components from different sources.

Pre-assembly also directly supports the reliability this holding point depends on: a unit built and tested as a complete assembly is less likely to develop the alignment or connectivity issues that can arise from field-improvised installations, which matters because a pilot relying on this fixture to stop safely before crossing an active taxiway needs the indication to be dependable every time, not just when installed correctly by chance.

Intermediate holding position fixtures are installed at various locations on the airfield where holding is required, particularly where a pre-assembled solution offers installation efficiency. They are used on:

• Intersecting taxiways where holding is required before crossing
• Approaches to active runways (intermediate holding positions)
• ILS critical area boundaries where holding is required
• Apron entry/exit points where traffic flow is managed
• Maintenance and construction zones where temporary holding is required
• Complex taxiway layouts requiring intermediate holding points

The pre-assembled unit is installed as a complete row across the taxiway at the intermediate holding position, with the factory-matched spacing and alignment of its individual lights setting the row's geometry rather than requiring that spacing to be re-established in the field. Frangible mounting bases are set into the pavement or shoulder at the positions fixed by the assembly's own frame, with the isolating transformers supplied as part of the unit typically housed in a below-grade pit adjacent to the row rather than integrated into the light housings themselves. Because the fixture is delivered pre-wired between its own lights and transformers, field installation is largely limited to positioning the assembly, connecting it into the site's primary series circuit, and confirming alignment against the taxiway's surveyed holding position, rather than assembling and wiring each light individually. Where the fixture marks a holding point serving an ILS critical area or similar sensitive boundary, its surveyed position is checked against that boundary specifically, since the holding line's accuracy is what the fixture exists to enforce.

Intermediate holding position fixtures operate as a pre-engineered, integrated lighting system:

• Assembly: The fixture consists of three light units mounted on a common base or individually on frangible couplings, with pre-wired connections to isolating transformers and junction boxes.
• Power: Powered from the constant current series circuit via an isolating transformer (typically 15W – 45W per light) integrated into the fixture assembly.
• Light Source: Utilizes yellow/amber LED arrays or yellow-filtered halogen lamps to provide a clear visual indication of the holding position.
• Configuration: The lights are arranged in a row across the taxiway at the holding position, with uniform spacing defined by the fixture design.
• Guidance: The fixture provides a consistent and reliable visual boundary, helping pilots and drivers to stop at the correct position and maintain safe separation.

An intermediate holding position fixture has no control logic beyond that of the ordinary AGL series circuit it's wired into — what distinguishes it architecturally is that the transformers, wiring, and light spacing arrive pre-assembled from the factory rather than being built up in the field. The same command that switches the adjacent taxiway edge lighting reaches this row through the shared CCR, and the row lights or extinguishes as the single assembly it was delivered as.

Because the internal wiring between lights and transformers is fixed at manufacture, fault isolation within the row itself depends on the assembly's own design — the CCR still only reports a fault at the loop level, so pinpointing which of the three lights in the row has failed relies on the same sectionalised testing used for any other loop-level fault.

As a pre-assembled fixture rather than a single moulded part, the unit is built up from a die-cast aluminium housing per light point, yellow/amber lens gasket-sealed against the housing, and a frangible mounting base that lets each unit shear cleanly under aircraft or vehicle impact. The individual light points are factory-spaced and pre-wired into a single harness during assembly, so the installer sets the row into its trench or base cans and makes only the primary and transformer connections rather than positioning and wiring each fixture separately. Each fixture in the row carries its own isolating transformer, housed in a base can beneath or beside it, with the secondary leads terminated to the fixture via L-823-style connectors and the whole assembly rated for outdoor, submersible service (IP66/IP67) against moisture, fuel spillage, and de-icing fluid.