Runway Pavement: ACN/PCN, ACR/PCR, Surface Friction, and What Gulf Buyers Specify

A query as plain as "tarmac used on the runway" sits on top of one of the most technical procurement areas in airport infrastructure: pavement. A runway is not just asphalt — it is an engineered pavement that must carry the heaviest aircraft using it, drain and resist rutting in extreme heat, and provide the surface friction that keeps a landing aircraft controllable. This brief explains how pavement strength is classified (ACN/PCN, now transitioning to ACR/PCR), the pavement types, the friction and surface requirements, and what a Gulf airport should weigh — without inventing thickness or strength figures, which are always design-specific.

How pavement strength is classified

ICAO provides a standardised way to publish a pavement's load-bearing strength and to check whether a given aircraft can use it:

• ACN/PCN (Aircraft Classification Number / Pavement Classification Number) is the long-standing system. Each aircraft has an ACN (a number expressing the relative load it imposes, for a given subgrade strength and pavement type), and each pavement is published with a PCN. If the aircraft's ACN is at or below the pavement's PCN (for the matching pavement type and subgrade category), the aircraft can use the pavement without special analysis. The PCN string also encodes pavement type (rigid/flexible), subgrade strength category, allowable tyre pressure, and how the value was derived.
• ACR/PCR (Aircraft Classification Rating / Pavement Classification Rating) is the successor system that replaces ACN/PCN. ICAO adopted it via Amendment 15 to Annex 14, Volume I (adopted 2020), with a four-year transition; the ACR/PCR method became applicable on 28 November 2024, after which ICAO's standard for reporting pavement strength is ACR/PCR rather than ACN/PCN. It modernises the methodology and the supporting software. In practice both systems are still seen during the changeover — published pavement data is being migrated, and some jurisdictions deferred adoption (notably the EASA states, where transposition into the EU framework was still in progress) — so buyers and planners should confirm which system a specification actually uses. The principle is the same — match the aircraft rating to the pavement rating — but the numbers and method differ, so ACN and ACR values are not interchangeable.

For a Code F / A380 hub (see the dedicated Code F brief), pavement classification is central: the A380 manages its very high mass through a multi-wheel main-gear layout precisely to keep its pavement loading manageable, and the pavement must still be rated to carry it.

Pavement types

• Flexible pavement (asphalt / bituminous) — layers of asphalt over a granular base and subbase. Flexible pavements distribute load through the layers and are common for runways, taxiways and aprons. They are sensitive to temperature: at very high pavement temperatures, asphalt can soften and rut under heavy, slow or static aircraft loads — a serious Gulf consideration.
• Rigid pavement (concrete / PCC) — Portland-cement concrete slabs that carry load by beam action and spread it over a wide area. Rigid pavement is often specified for aprons and stands where aircraft sit static for long periods (and where fuel/oil spillage and jet-blast occur), because it resists the rutting and softening that heat and static loads cause in asphalt.
• Composite — combinations, e.g. asphalt overlays on concrete.

A common Gulf pattern is rigid (concrete) pavement at stands and aprons where heat and static loads are worst, with flexible or composite pavement on runways and taxiways, but the choice is always a design decision driven by loads, climate and lifecycle cost.

Surface friction and texture

Strength is only half the story — the runway surface must also provide friction so a landing or aborting aircraft can brake and steer:

• Surface texture (microtexture and macrotexture) and treatments such as grooving (transverse grooves cut into the surface) improve water drainage and braking, reducing the risk of hydroplaning in rain.
• Friction must be measured and maintained — ICAO requires runway surface-friction characteristics to be assessed, and friction degrades over time from rubber deposits (built up in the touchdown zone from tyre contact) and wear. Rubber removal and friction-restoration are recurring maintenance procurements.
• The Global Reporting Format (GRF) is the ICAO standardised method for assessing and reporting runway surface conditions (the Runway Condition Report / RWYCC), which airports must operate.

The standards and references

• ICAO Annex 14, Volume I — aerodrome design, pavement and surface requirements, geometry and the ACR/PCR (formerly ACN/PCN) framework.
• ICAO Doc 9157, Aerodrome Design Manual, Part 3 (Pavements) — detailed pavement design and evaluation guidance.
• ICAO GRF / Doc 10064 (Aeroplane Performance Manual) and the associated runway-condition-reporting framework.
• FAA Advisory Circulars (e.g. AC 150/5320-6 for pavement design, AC 150/5320-12 for friction) are widely referenced internationally alongside ICAO.
• National civil-aviation authority requirements (GCAA, GACA, QCAA, etc.) transpose these.

GCC-specific considerations

• Extreme heat is the dominant Gulf pavement factor: high pavement temperatures drive the choice of binder/asphalt grade and favour rigid concrete at static-load areas (stands, aprons) to resist rutting. Specifications should call for binders and mixes designed for the local high-temperature climate.
• Thermal cycling (hot days, cooler nights) and UV degrade surfaces over time.
• Sand and dust on the surface affect friction and require cleaning regimes.
• Heavy widebody / Code F traffic at Gulf hubs sets demanding pavement-strength requirements.
• Construction phasing — runways and taxiways must often be resurfaced or strengthened without closing the airport, so night-work and rapid-cure materials are real procurement parameters.
• Friction maintenance (rubber removal, grooving, friction testing) is a recurring service procurement, not a one-off build item.

What this means for procurement

Pavement procurement splits into two streams: the capital build/strengthening (new runway, taxiway, apron, or an overlay/strengthening project) and the recurring surface maintenance (friction testing, rubber removal, grooving, repairs). For capital work, the basis is the design aircraft and its ACR (or legacy ACN), the subgrade, and the local high-temperature climate — driving pavement type (rigid at static-load areas, flexible/composite elsewhere) and material specification, designed to ICAO Doc 9157 and the national authority's requirements. For maintenance, the basis is the GRF/friction regime and the rubber-deposit cycle. Confirm whether the specification uses ACN/PCN or the newer ACR/PCR, because the numbers are not interchangeable. Suppliers span specialist airfield-pavement contractors, asphalt/concrete and binder suppliers, grooving and friction-testing specialists, and rubber-removal service providers; the right partner depends on which stream — capital or maintenance — the project sits in. The design aircraft, the climate, and the classification system come before any material or contractor choice.