The words active and passive are used in several seemingly-conflicting ways in the context of automobile safety. At the most basic level, the terms apply to the vehicle occupant’s involvement in the function of the safety device or system:
- Active: safety devices and systems are those which the vehicle occupant must act to make functional, as for example by fastening a seat belt.
- Passive: safety devices and systems are those which operate without any input or action from the vehicle occupant.An example is active head restraints, which move to a position optimal for preventing neck injury when a collision is imminent.
Crash avoidance
Crash avoidance systems and devices help the driver to avoid a collision. This category includes:
- The vehicle’s headlamps, reflectors, and other lights and signals
- The vehicle’s mirrors
- The vehicle’s brakes, steering, and suspension systems
Driver assistance
A subset of crash avoidance is driver assistance systems, which help the driver to detect ordinarily-hidden obstacles and to control the vehicle. Driver assistance systems include:
- Traction control systems which restore traction if driven wheels begin to spin
- Tire pressure monitoring systems or Deflation Detection Systems
- Reverse backup sensors, which alert drivers to difficult to see objects in their path when reversing
- Electronic Stability Control, which intervenes to avert an impending loss of control
- Lane departure warning systems to alert the driver of an unintended departure from the intended lane of travel
- Adaptive cruise control which maintains a safe distance from the vehicle in front
- Anti-lock braking systems
- Electronic brakeforce distribution systems
- Cornering Brake Control systems
- Emergency brake assist systems
- Forward Collision Warning Systems
- Dynamic Brake Control systems
Crashworthiness
Crashworthiness systems and devices prevent or reduce the severity of injuries when a crash is imminent or actually happening. Much research is carried out using anthropomorphic crash test dummies.
- Seatbelts limit the forward motion of an occupant, stretch to slow down the occupant’s deceleration in a crash, and prevent occupants being ejected from the vehicle.
- Airbags inflate to cushion the impact of a vehicle occupant with various parts of the vehicle’s interior.
- Laminated windshields remain in one piece when impacted, preventing penetration of unbelted occupants’ heads and maintaining a minimal but adequate transparency for control of the car immediately following a collision. tempered glass side and rear windows break into granules with minimally sharp edges, rather than splintering into jagged fragments as ordinary glass does.
- Crumple zones absorb and dissipate the energy of a collision, displacing and diverting it away from the passenger compartment and reducing the impact force on the vehicle occupants.
- Side impact protection beams.
- Collapsible steering columns reduce the risk and severity of driver impalement on the column in a frontal crash.
- pedestrian protection systems.
- Padding of the instrument panel and other interior parts of the vehicle likely to be struck by the occupants during a crash.
Pedestrian safety
Since at least the early 1970s, attention has also been given to vehicle design regarding the safety of pedestrians in car-pedestrian collisions. Proposals in Europe would require cars sold there to have a minimum/maximum hood height. From 2006 the use of fashion on 4×4s and SUVs, became illegal.
Conspicuity
A Swedish study found that pink cars are involved in the fewest accidents, with black cars being most often involved in crashes.
In Auckland New Zealand, a study found that there was a significantly lower rate of serious injury in silver cars; with higher rates in brown, black, and green cars.
