The “Bending Plate” from IRD-PAT Traffic is used for Weigh-In-Motion (WIM). The importance of measuring the loads of driving road vehicles has increased enormously. Traffic safety, the protection of the infrastructure road and statistical data are the main purpose of Weigh-In-Motion equipment.

The stationary weighpads are delivered in two sizes for different width of lanes: WP 1250 and WP 1750


  • Excellent long term stability
  • Speed range: 5 to 200 km/h
  • Robust
  • Long life time (> 10 year)


  • Traffic monitoring
  • Road maintenance planning
  • Overload detection
  • Toll applications
  • Statistical purpose

The foundation is made of high-strength steel plates. On the bottom side two slots are milled for the incorporation of wire strain gauges. The wire strain gauges are bridged to a Wheatstone-Bridge with supplementary fixed resistors for temperature compensation. The supply voltage and the output signal are carried in a shielded 4 conductor cable inserted through a hole with waterproof fitting.
The whole weighpad is covered with a neoprene rubber film hot vulcanised on. Along the longitudinal borders two rubber tapes, used as bearings, are vulcanised on the bottom side.

For fixing the weighpad, it is bevelled on both sides at the longitudinal borders and supported by two bevelled strips in a foundation frame.

The foundation frames are tied firmly in the road surface by a special installation procedure. Details are described in a separate installation manual.

Bending Plate

Technical data

  • Weight: 81 kg for 1250 mm version, 114 kg for 1750 mm version
  • Sensor Dimensions: 508 x 1250 x 23 mm (WP1250 mm), 508 x 1750 x 23 mm (WP1750 mm)
  • Nominal Load: 10.000 kg
  • Carrying capacity: 15.000 kg
  • Temperature range: -40ºC … +80ºC (stock and operation without damage)
  • Temperature range: -10ºC … +50 ºC,(compensated)
  • Continual stock temperature: +15 ºC … +30 ºC (more then 3 months)
  • Air humidity: 10% … 99%
  • Uninterrupted water influence: < 300 hours
  • Temperature drift sensitivity: ± 0.01% / ºC
  • Temperature drift zero point: ± 0.2% / ºC
  • Linearity (increasing load): ± 0.7% from measuring range
  • Traverse sensitivity: 1.5% from measuring range
  • Sensitivity (10t): ± 0.8 (0.6) mV/V typ.
  • Length of connecting cable: 40 m (standard)
  • Number of conductors: 4 + shield
  • Input resistance: 650 ohms (975 ohms) typ.
  • Output resistance: 600 ohms (840 ohms) typ.
  • Insulation resistance: > 100 MOhms
  • Supply voltage: 24V DC (30V DC max.)
  • Max. voltage measuring
  • circuit shield: 100V
  • Natural frequency: 215 Hz