Backing Aids

Hover to enlarge

  • Red car that is backing in to a parking space is alerted that there is a black car parked in the space behind it.

Backing aids detect the presence of objects behind a vehicle when it is in reverse (backing up). Most use ultrasonic sensors. When sensors detect an object behind a vehicle, the system turns on a warning light or a warning sound to let you know how close your vehicle is to the object. Camera systems also exist, which display the monitoring area on a screen in front of the driver or in a specially modified rear view mirror.

Other systems, known as cross path detection, assist drivers in backing up in places such as parking spots.  These systems detect if a vehicle is approaching as they are backing up and notify the driver with audio and visual alerts.

iso symbol for automatic parkingAutomatic parking systems help drivers parallel park or back into a parking spot. Once the system identifies an appropriate parking spot, the driver is prompted to accept the driving assistance. The system steers the vehicle while the driver controls the gas and brake pedals.


These systems turn on when you put your vehicle in reverse. Some take longer to activate than others.

Sensor-based systems vary by manufacturer

  • Maximum distance detected behind the vehicle can range between 1 and 2.4 metres
  • Minimum object height detected can range from 42 to 64 cm

Automatic parking systems

The driver activates the system by pressing a button on the instrument panel. The driver can interrupt the system by taking hold of the steering wheel.

Things to keep in mind

Sensor systems

  • Are poor at detecting people
  • Have a high nuisance factor (false alarms) and many owners turn them off after a while.

Camera systems

  • Most provide full coverage of the rear of the vehicle - more so than sensor systems.
  • Most camera systems do not alert the driver.
  • Conditions such as rain, darkness, glare, dirt on the camera can make viewing difficult.
  • Effectiveness depends on drivers reversing slowly enough (less than 3 km/h) to give the driver enough reaction time.
  • Effectiveness also depends on the driver. Looking over your shoulder, checking the display image and mirrors frequently, improves the chances of detecting obstacles.

These systems do not replace careful driving.

Drivers who trust these systems too much may be less careful when driving in reverse (not looking out for pedestrians or small children; use the mirrors less; make fewer shoulder checks; and drive too quickly).

Backing aids are designed primarily to help you park. Don’t rely on them to detect pedestrians or small children. Remain alert whenever you drive in reverse, especially when small children could be in the area.

Learn more

  • Vehicle Backover Avoidance Technology Study, Report to Congress, November 2006, National Highway Traffic Safety Administration U.S. Department of Transportation
  • An Investigation of the Potential Safety Benefits of Vehicle Backup Proximity Sensors, Viliam Glazduri, Transport Canada, Paper Number 05-0408, 19th International Technical Conference on the Enhanced Safety of Vehicles (ESV), Washington, June, 2005. DOT HS 809 825

Date modified: