Don’t blindly trust collision-avoidance system on your car
Beware: snow, ice and even sunlight can disable the best technology
Collision mitigation systems are becoming more and more popular on even the mundane entries and offerings of the automotive world. Lane-departure warning and assist, forward-collision warning and active braking, blind-spot monitoring and rear-view cameras have all rooted themselves on option sheets next to power moonroofs and tri-zone climate control.
Some vehicles have advanced to almost autonomous operation, with speed controls that will allow you to stop without driver input when traffic ahead stalls and to resume your journey velocity from a standing start. They can selectively apply individual wheel brakes to nudge you back into your lane when you wander. There are systems that can distinguish pedestrians from vehicles, which monitor not only the road ahead but objects moving along the side and from intersecting streets.
But on our Canadian roads, especially with inclement weather, how well do these systems operate when the snow blows, or the fog sets in, or even when the sun is shining?
It’s important to understand how the different systems work. Most lane-departure warning/assist/ avoidance systems use cameras on both sides of a vehicle. The cameras constantly scan downward to the road’s surface to detect painted lane-marker lines. It’s a no brainer that if the road is covered in snow or slush, or if the lines have worn away, this camera system won’t be of much use. Automakers don’t provide any type of warning that the lane-departure system is offline when the marker lines can’t be read.
Blind-spot and cross-path detection systems, for the most part, use radar technology. A small radar signal transmitter/receiver (about the size of a deck of playing cards) is mounted on each side of the vehicle, usually in the rear fender area. While studies have shown that rain can affect the operation of these units, moisture only comes into play if the radar lens itself gets wet. These units are installed inside the rear fender/quarter-panels, so they are unlikely to become water covered. Heavy snow can have a minor effect, but as the real targets of the units are much larger and denser than snow, and as the system is short-range, the white stuff doesn’t seem to have much effect on their operation. System failures will be indicated to the driver via an instrument panel warning and, in these cases, the system will go off-line to prevent unwarranted braking or steering actions.
Most forward-collision warning/ mitigation and adaptive speedcontrol systems also use a radar unit usually mounted behind the front grille. While automakers do their best to offer protection against road debris and weather impacts for these sensors, ice and snow buildup on the front face of a vehicle can disable this system. It’s common enough that most automakers program a specific driver warning into these systems that will display a “clean radar sensor” message when they no longer register a signal because of foreign material buildup.
Many drivers know of the headaches of rear-view camera systems that become disabled by snow and ice buildup on their very vulnerable locations near the rear licence plate. Even those protected behind a shield, such as VW’s pop-up rear camera, can be rendered inoperative if the cover can’t open because of an ice obstruction.
One of the latest technologies — Subaru’s EyeSight system — is prone to being disabled by sun glare. This patented system uses two forward-facing cameras mounted behind the top of the windshield and their spacing and monitoring devices allow them to “see” in stereo. This more accurately distinguishes the distance of objects in the path of the vehicle and the direction those objects are moving. They can also be “blinded”by heavy precipitation or fog.
Subaru, like other manufacturers, has built in a safeguard that prevents its collision-mitigation system from activating brakes or warning drivers when it can’t “see” well enough to operate. The driver is notified via the instrument cluster and the system will resume automatically when things clear up.
Google, the leader in autonomous driving technology, recently discovered its own fleet of vehicles is prone to weather phenomena and, unlike human drivers, the Google cars simply pull over and stop when their systems can’t “see” clearly enough to continue driving.
The biggest drawback in any collision-mitigation system is they can’t fill in the blanks. We constantly experience driving situations where we don’t have clear uninterrupted sight lines of the road ahead or traffic around us. We are capable of predicting movement of objects based on their direction, speed, and the presence of turn signal or brake lamps. These assumptions and predictions allow us to navigate, even though weather or traffic conditions aren’t ideal. When the current level of mitigation-system control computers are faced with even momentary distractions or sensor blockages, they simply disable themselves.
Collision-mitigation systems and autonomous-driving technology aren’t likely to fade away, as they have proven themselves to reduce collisions and save lives. But their biggest risk is increasing driver complacency and causing too much reliance on their limited abilities. Consider how we have become accustomed to such features as power windows, speed control, navigation systems and such. When we become reliant on vehicle technology it is much easier for our momentary lapses in attention to lead to tragedy.
The next wave in collision-mitigation systems to be rolled out will involve wireless communication between vehicles. This holds the promise of systems that can accurately predict vehicle interactions by knowing exact locations and directions of travel as well as speed and whether or not a driver has activated the brakes or is accelerating or has turned on a turn signal. Prototypes have been on the road for several years and have proven very effective in real-world testing.
Some even have the ability to monitor smartphones to detect if a texting pedestrian is about to take his or her final steps into the path of an oncoming car and can flash a warning on the phone screen to get the distracted walker’s attention.