Vehicle Detection Sensor

A Vehicle Detection Sensor is a specialised surveillance device designed to detect and track ground vehicles operating on the airfield surface—including runway sweeper trucks, maintenance vehicles, fuel trucks, baggage tugs, and other support vehicles. These sensors provide real‑time vehicle presence and movement data to Air Traffic Control, Airport Operations Centres, and runway incursion prevention systems. Unlike aircraft detection sensors that are optimised for larger targets, vehicle detection sensors are engineered to reliably detect smaller, slower-moving targets (typically 1‑5 tonnes) with high sensitivity and low false‑alarm rates. They are deployed at critical locations such as runway crossings, taxiway intersections, vehicle access points, and runway ends. The sensor data is integrated with A‑SMGCS (Advanced Surface Movement Guidance and Control Systems), RWSL (Runway Status Light) systems, and ATC displays to provide comprehensive surface surveillance, enabling controllers to manage both aircraft and vehicle movements safely and efficiently, particularly during low‑visibility operations and complex ground movements.

The vehicle detection sensor exists to close a specific blind spot in surface surveillance: aircraft detection systems are tuned for large, predictable targets, while service vehicles are smaller, move less predictably, and are exactly the kind of traffic a controller can lose track of during a busy ground movement sequence, particularly in low visibility. By giving ATC and A-SMGCS the same real-time presence and movement data for vehicles that they already have for aircraft, the sensor lets vehicle and aircraft movements be managed within a single coherent picture rather than the vehicle side being managed by memory, radio position reports, or visual observation from the tower alone. This matters most at the exact locations, runway crossings and taxiway intersections, where an undetected vehicle would otherwise pose the greatest incursion risk.

Vehicle Detection Sensors are deployed at critical locations across the airfield where ground vehicle movements pose a potential conflict with aircraft operations:

• Runway Crossings: Detecting vehicles approaching or crossing active runways to prevent incursions and trigger warning systems.
• Taxiway Intersections: Monitoring vehicle movements at busy taxiway intersections to enhance situational awareness.
• Vehicle Access Points: Detecting vehicles entering the airside from landside access gates.
• Runway Ends (Threshold Areas): Monitoring vehicle activity near runway thresholds during maintenance or inspection operations.
• Apron Areas: Tracking ground support vehicles (fuel trucks, baggage tugs, catering vehicles) for improved apron management.
• Runway Status Light (RWSL) Systems: Providing vehicle detection input for Runway Entrance Lights (REL) and Takeoff Hold Lights (THL).
• A‑SMGCS (Advanced Surface Movement Guidance and Control Systems): Integrating with A‑SMGCS for comprehensive surface surveillance and conflict detection.
• ATC Towers: Providing controllers with real‑time vehicle location and tracking data, enhancing situational awareness.
• Airport Operations Centers: Monitoring fleet vehicle movements for operational planning and resource allocation.

Sensors are positioned at the runway crossing, taxiway intersection, or access gate they monitor, mounted either as an in-pavement inductive loop (cut and sealed into the surface) or as a pole-mounted microwave/infrared unit set back clear of vehicle and aircraft clearance envelopes. Mounting height and detection-zone aim are set out so the zone covers the full width of the crossing or gate without extending into an adjacent lane where it would generate false triggers. Detector cabling runs on its own screened pair back to the local controller or Remote I/O rather than sharing conduit with unrelated lighting circuits, since the output typically drives a warning light or gate interlock directly.

The Vehicle Detection Sensor uses advanced detection technologies optimised for smaller, slower targets. Key functional aspects include:

• Detection Technologies: Sensors typically use one or a combination of:
  • FMCW Radar (24 GHz or 77 GHz): Detects moving vehicles with high sensitivity, providing range, speed, and position information, immune to weather and lighting.
  • Infrared (active or passive): Uses thermal signatures or reflected IR to detect vehicles, effective in darkness, fog, and smoke.
  • Inductive Loops: Buried loops detect metallic vehicles passing over; simple and reliable, but limited to fixed points.
  • Video Analytics (AI/CCTV): Uses camera footage with machine learning algorithms to detect and classify vehicles, providing visual confirmation.
  • Fusion Sensors: Combine multiple technologies (e.g., radar + IR + video) for improved detection reliability and false‑alarm rejection.
• Target Classification: Advanced sensors can differentiate between vehicles and aircraft, or between different vehicle types (e.g., fuel truck vs. baggage tug), to provide more meaningful data to controllers.
• Coverage Zone: The sensor is positioned to cover a specific area—typically 50‑300 metres for radar/IR, or a precise detection point for inductive loops.
• Speed and Direction Detection: Radar sensors can determine vehicle speed and direction of travel, providing valuable information for conflict prediction.
• Output Signal: The sensor provides a clean, isolated output—typically a dry contact, transistor output, or digital message (Ethernet/Modbus)—that indicates vehicle presence, speed, and direction. The output is connected to the RWSL processor or A‑SMGCS.
• Self‑Diagnostics: The sensor continuously monitors its own health (power, communication, signal quality) and provides diagnostic outputs for proactive maintenance.

Vehicle detection sensors are typically mounted on poles adjacent to the monitored area, on overhead gantries, or integrated into existing airfield infrastructure. Their position and sensitivity are carefully calibrated to detect vehicles while ignoring small objects (birds, debris) and reducing false alarms.

Like the Stop Bar Sensor it is closely related to, the Vehicle Detection Sensor is a detection input rather than a decision-maker — it reports the presence of a smaller, slower-moving target (a service vehicle or piece of ground equipment) to a Remote I/O unit or local PLC, and the access-control or ALCMS logic upstream decides what to do with that information: hold a gate or barrier, trigger a warning light, or log the crossing. It does not itself energise any actuator or lighting circuit. Because it is tuned to detect targets smaller and slower than the aircraft the Stop Bar Sensor is designed around, it is typically deployed at vehicle crossing points and service road junctions rather than on the runway itself, and a fault is reported and handled the same conservative way — as a loss of detection at that location, not as an assumption that the crossing is clear.

The sensor head is housed in a sealed, weatherproof enclosure — die-cast aluminium or glass-reinforced polymer — rated IP65/IP67, with a radome or optical window covering the radar, IR, or camera aperture to protect it from rain, dust, and de-icing overspray while remaining transparent to the sensing wavelength. Pole-mounted units bolt to an adjustable bracket that allows azimuth and elevation to be set and locked during commissioning, and where video analytics are used, the camera module is a separate sealed unit connected to the processing electronics by a short weatherproof cable run. Internal electronics are conformally coated and connected through sealed M12 or similar circular connectors rather than open terminal strips, keeping moisture out of the detection and output circuitry. Built-in transient voltage suppression is mounted near the cable entry point to protect against lightning-induced surges, and the enclosure includes a grounding lug for bonding to the site's lightning protection system.