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October 6, 2020


It may have just turned to fall on 2020 calendars, but for those in the automotive industry, it more than likely means thoughts of winter automotive issues are getting uncomfortably close. Let’s examine a topic sure to cause headaches this season – Advanced Driver Assistance System (ADAS)-equipped vehicles and how they handle winter driving.

Manufacturers all have their own names for the functions making up ADAS. Honda calls it Honda Sensing. Cadillac calls it Super Cruise, and Tesla calls it Autopilot. Basically, ADAS makes a car sort of drive itself – from simply warning you when someone is in your blind spot to literally steering and braking for you. These technologies are finicky at best and sometimes have operational quirks even in ideal conditions. So, what happens when you add snow on the road? Does road salt get packed on the vehicle’s radar? Does this system stand a chance of operating well on an icy road with unclear markings? If you’ve ever driven in a blizzard, it can be hard to see anything let alone which lane you’re in.

Let’s first examine ADAS technology. Take Honda Sensing suite as our example. It’s a pretty good system with basic nuts and bolts you can use to try to intuit operation on other vehicles. One of the biggest hurdles in these systems is decoding the long list of acronyms:

(All photos/illustrations throughout this article are courtesy of Honda.)

Forward Collision Warning (FCW), Lane Departure Warning (LDW), Lane Keeping Assist (LKAS), and Blind Spot Information (BSI) are just a few of the acronyms which Honda makes fairly intuitive. For example, the Collision Mitigating Braking System (CMBS) sounds like it will warn you of an impending collision and possibly apply the brakes for you if there is no intervention and this is indeed what the system does. Lane Keeping Assist also sounds like what it does – steer a vehicle back into its lane when it roams out of it.

Most of these systems are made possible due to two bits of hardware – a windshield-mounted camera and a millimeter wave radar mounted behind the front grill.

These two components work in tandem with the traction control and electric power-steering systems to make driving a car a little more mindless (and sometimes scary).

The radar is generally used for detecting solid objects, whether in motion, standing still, or in a non-linear trajectory in comparison with the vehicle’s own. The camera detects solid objects, as well as detecting lane markings and speed limit signs. If either the camera or radar calculate you are drifting out of your lane or coming up fast on a car or pedestrian, they have the traction control system and/or power steering system intervene.

Lane control uses the front camera only, as it must detect road markings that the radar cannot see.

The Forward Collision Warning, Collision Mitigation Braking System (CMBS), and Adaptive Cruise Control are all functions of both radar and camera working together.

I can tell you the Lane Keeping Assist’s (LKAS) opinion of what “being in my lane means” versus a driver’s own opinion can sometime differ significantly. Drivers may sometimes notice the LKAS warning chime and corresponding wheel nudge if they are being inattentive and unaware of their lane position. Unfortunately, sometimes the LKAS, when allowed its druthers, will wander lane line to lane line, picking which one it can see best. This can give the impression the vehicle is being piloted by a drunk driver.

However, a CMBS can sometimes choose to sound the alarm when coming to a perfectly reasonable stop or, on the flip side, be radio silent when coming up fast on someone’s bumper.

As it’s a learning system, it will get a bit better as it learns a driving style. But even under ideal conditions, there can be glitches and hiccups in operation. Now imagine how this advanced technology will do under severe conditions such as snow, ice, and blizzards.

Every Original Equipment Manufacturer (OEM) has a long list of system caveats for weather and related road conditions. Be sure to consult the owner’s manual for specifics, but the list usually goes a bit like this.

Environmental conditions such as:

  • Driving in bad weather (rain, fog, snow, etc.)
  • Sudden changes between light and dark such as a tunnel entrance or exit
  • Little contrast between objects on the road and the background
  • Driving into low sunlight such as at dawn or dusk
  • Strong light reflected onto the roadway
  • Driving in the shadow of buildings, trees, etc.
  • Roadway objects or structures misinterpreted as vehicles and/or pedestrians
  • Reflections on the interior of the windshield
  • Driving at night or in a dark condition such as a tunnel

Rodway conditions such as:

  • Driving on a snowy or wet roadway with obscured lane markings, vehicle tracks, reflected lights, road spray, or high contrasts
  • A hilly road or when the vehicle is approaching the crest of a hill
  • Driving on a curvy, winding, or undulating road.

Vehicle conditions such as:

  • Dirty headlight lenses or improperly adjusted headlights
  • A windshield blocked by dirt, mud, leaves, wet snow, etc.
  • A fogged windshield
  • An abnormal tire or wheel condition (wrong size, varied size or construction, improper inflation, compact spare tire, etc.
  • When tire chains are used
  • A tilted vehicle due to a heavy load or suspension modification
  • If the vehicle’s camera temperature gets too high
  • Driving with the parking brake applied
  • A dirty front grill affecting the radar sensor

If any of these conditions occur, you can expect erratic , or possibly no ADAS functionality at all. Tesla even warns about kangaroos. The point is to show that these seemingly miraculous bits of hardware/software are still far from perfect.

The above illustrates some of the conditions involving just road markings on clean roads where an LKAS malfunction could occur.

Some vehicles will literally tell you to go clean off the radar area at the front grill. This actually happens frequently, forcing a driver, in some cases, to stop to do this several times on a single drive. Should a customer driving an ADAS-activated vehicle come into your shop complaining about operations during the icy and snowy months, make sure to educate them about some of these winter-related driving issues. Then wipe off the windshield and the front grill, and advise your customer to wait until roads are clear and dry before again engaging ADAS. Better yet, suggest to your customer that they would be better served to retire the ADAS systems between November and March.


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