Pavement Temperature Sensor

A Pavement Temperature Sensor is a specialized monitoring device installed in the surface of airfield pavements to measure the temperature of the asphalt or concrete surface. These sensors provide real-time data that is critical for:

• Winter maintenance decisions — determining when anti‑icing and de‑icing treatments are needed
• Friction assessment — understanding how temperature affects runway friction characteristics
• Pavement performance monitoring — tracking thermal stress and seasonal variations
• Flight planning — providing data for aircraft performance calculations (take‑off and landing distances)
• AGL equipment protection — helping to prevent damage from extreme pavement temperatures

Modern sensors use either contact (RTD, thermocouple) or non‑contact (infrared) technologies, with robust housings designed to withstand heavy aircraft loads and harsh environmental conditions.

The pavement temperature sensor exists because the same air temperature reading can correspond to very different runway surface conditions depending on solar loading, wind, and precipitation history, and it is the surface, not the air above it, that determines when ice actually forms. Feeding real, measured pavement temperature into winter maintenance decisions lets ground crews time anti-icing and de-icing treatments to when they are actually needed rather than on a fixed schedule or a conservative worst-case assumption, reducing both the risk of an untreated icy surface and the cost of treating pavement that did not need it. The same reading also has value beyond winter operations, since surface temperature directly affects the friction values used in landing distance and braking action assessments.

Pavement temperature sensors are installed at strategic locations across the airfield to provide comprehensive thermal monitoring:

• Runways — at multiple points along the length (touchdown zone, mid‑point, and end) to capture thermal gradients
• Taxiways — to monitor pavement conditions for aircraft ground movement
• Apron and parking stands — to support de‑icing operations and ground handling
• Instrumented pavements — integrated with weather stations and friction measurement systems
• Remote airfields — where manual temperature monitoring is impractical

Data from these sensors is typically integrated into the airport’s weather observation system, ALCMS, or winter maintenance management platform for automated alerting and decision support.

Contact sensors are set flush into the pavement surface at each monitoring point — typically the touchdown zone, mid-point, and far end of the runway, plus key taxiway and apron locations — with the probe body seated in a cored hole and bedded in a thermally conductive grout so it reads the true pavement temperature rather than an air gap. Signal cable runs from the probe through a small conduit stub to a roadside or shoulder-mounted junction box, then in duct back to a remote terminal unit or the airport weather station. Non-contact infrared units are instead mounted above the pavement on a pole or gantry with a clear, unobstructed view of the surface being measured, positioned clear of the aircraft movement area and any frangibility requirements that apply to fixed structures near the runway.

Pavement temperature sensors operate using one of the following principles:

• Contact Sensors (RTD / Thermocouple): A resistive temperature detector (RTD) or thermocouple is embedded in a metallic probe that is in direct contact with the pavement surface. The probe is installed flush with the pavement, and the sensor measures the temperature of the material. These provide high accuracy and fast response times.
• Infrared (IR) Sensors: A non‑contact sensor measures the infrared radiation emitted by the pavement surface. It is mounted above the pavement (e.g., on a pole or gantry) and measures surface temperature without physical contact. This method is less invasive but can be affected by atmospheric conditions and surface contamination.
• Wireless / IoT Sensors: Many modern sensors include wireless communication (LoRa, ZigBee, cellular) to transmit data to a central collection point, reducing installation complexity and enabling remote monitoring.

The sensor outputs standardised signals (e.g., 4‑20 mA, 0‑10 V, digital (MODBUS, SDI‑12)) that are read by a data logger or directly by the airport’s monitoring system. Calibration is performed to ensure accurate readings across the expected temperature range.

The pavement sensor itself is a passive measurement point; the control logic lives in the Runway Weather Information System (RWIS) it feeds. Embedded sensors report pavement surface and sub-surface temperature — and on combined sensors, surface state and freeze-point depressant concentration — over a wired loop to a field processor, which polls each sensor at a set interval and packages the readings for transmission to the central RWIS server. The server compares readings against forecast and threshold data to generate a freezing/frost risk assessment, which is displayed to airfield operations and can trigger a deicing or anti-icing response; sensor dropout or an out-of-range reading is flagged as a data-quality fault so operators don't mistake a failed sensor for confirmed dry pavement.

A contact probe (RTD or thermocouple) is a compact, stainless-steel or corrosion-resistant sensor head set into a flush-mounted housing that seats within the pavement structure, load-rated to withstand full aircraft wheel loading without disturbing the surrounding surface. The sensing element sits close to the exposed top face for a fast, representative reading of pavement skin temperature, with the housing gasket-sealed and potted internally to achieve an IP67/IP68 rating against water and de-icing fluid ingress. An infrared variant instead mounts above the pavement on a small elevated bracket or pole, aimed down at the surface with no physical contact, trading installation simplicity for a slightly lower accuracy and a need for a clear, unobstructed sightline. Signal cabling — typically twisted-pair for 4-20 mA or MODBUS/SDI-12 output — runs from the sensor through a sealed conduit to a nearby junction box, then on to a remote power supply or data logger, with the underground run protected against pavement loading the same way as other in-ground AGL cabling.