Nearly hit from behind because Clarity slamed on the brake

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bpratt

bpratt

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I was driving on the freeway in a heavy rain with cruise control set on. I was driving in the right lane because I wanted to take the next exit. A large truck passed me on the left side and kicked up a large cloud of water. I guess my car thought the cloud of water was a very slow moving vehicle, so it hit the brake hard. The car behind me had to hit their brake and probably came within a couple of feet of hitting me. Once the cloud of water cleared a little, the car release the brake and continued on and left me with my heart pounding.
 
While a heart pounder, it’s normal and expected behavior under those circumstances considering the sensors involved. The manual on page 406 lists ACC with LSF Conditions and Limitations. Driving in bad weather (rain, fog, snow, etc.) is one of several listed. I should not use my ACC in heavy rain. Thanks for reminding me. You may save someone’s life by sharing your experience.
Some need to be reminded that all the driving tech in our Claritys is driver ASSIST, not auto pilot.
 
Do you guys think that braking was due to ACC or did the collision mitigation system? If the latter, not driving in ACC wouldn’t have made any difference.
 
Fast Eddie B said:
Do you guys think that braking was due to ACC or did the collision mitigation system? If the latter, not driving in ACC wouldn’t have made any difference.
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Im going to go out on a limb and say it was probably the ACC since the trigger event seems to have been an instantaneous type of thing. The CMBS needs to see a certian range of closing or delta velocity to activate and mine seems to take a second and gives me a warning beep first. But absent noticing any dash warning, we can’t know for 100% certainty.
 
bpratt said:
I was driving on the freeway in a heavy rain with cruise control set on. I was driving in the right lane because I wanted to take the next exit. A large truck passed me on the left side and kicked up a large cloud of water. I guess my car thought the cloud of water was a very slow moving vehicle, so it hit the brake hard. The car behind me had to hit their brake and probably came within a couple of feet of hitting me. Once the cloud of water cleared a little, the car release the brake and continued on and left me with my heart pounding.
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One can drive through most auto-braking relatively quickly and easily (in terms of force needed); I get that it takes a moment to analyze and jump in, but you really have to stay on top of it. I find that I can catch it pretty fast (in ACC), before any significant slow down.

I worry a lot about the opposite, that I am so used to overriding auto braking in ACC, that someday I may defeat the auto-braking out of habit, when it is correctly trying to save me!
 
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Do NOT use cruise control in any rain heavy enough to puddle water on the roadway. Even safer is not to use it in rain at all.

I lost control of Jaguar XJR on I4 in FL. The culprit was hydroplaning, and I was using cruise control. I can’t be sure it would not have happened anyway, but I’ve been very gunshy of cruise control in the rain ever since.
 
bpratt said:
I was driving on the freeway in a heavy rain with cruise control set on. I was driving in the right lane because I wanted to take the next exit. A large truck passed me on the left side and kicked up a large cloud of water. I guess my car thought the cloud of water was a very slow moving vehicle, so it hit the brake hard. The car behind me had to hit their brake and probably came within a couple of feet of hitting me. Once the cloud of water cleared a little, the car release the brake and continued on and left me with my heart pounding.
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Thanks for reminding us that cruise control should be turned off in rain, ice, and snow. Leaving it on in those conditions is a recipe for disaster. Glad that you weren't rear ended.

Sent from my SM-G955U using Inside EVs mobile app
 
bpratt said:
I was driving on the freeway in a heavy rain with cruise control set on....
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Honda is pretty clear about this practice. This is a Clarity Owner's manual direct quote:

WARNING: Improper use of ACC with LSF can lead to a crash.
Use ACC with LSF only when driving on expressways or freeways and in good weather conditions.

In my claim adjuster days, not long ago, I handled a claim on a Subaru Legacy with Eyesight (competitive/similar system to Honda Sensing). I was an independent adjuster and rep'd the insurance company. Owner/customer insisted to me that the car suddenly self-accelerated up her long snowy driveway and caused her to ram straight into a large tree on her own property, and she wanted to blame Subaru for having a defect somewhere and have the car investigated. Wanted the insurance company to subrogate against Subaru for cost of the accident. I also inspected the accident scene at her home, and didn't doubt that her description is exactly what happened, though she insisted she was stepping on the brake as it was accelerating, and the car wasn't responding to the brake. I had no way of knowing whether that statement was true without a black box investigation where we hire specialists to read the computers for the actions of the drivers, and the car, in the moments leading to the accident. She specifically said she bought the car for the Eyesight feature, and drove with it activated 100% of the time for safety reasons.

So I ran it up the line for review. Did they want to pay for the black box investigation and look into this claim further? The insurance company legal reps took one quick look at Subaru's warnings in the owner manual about never having ACC activated on any secondary roads (much less driveways), never use it in the snow/bad weather, etc...and then flatly informed the customer that she was 100% responsible for the crash by having the ACC activated at times when she clearly should not have. She didn't read/understand the clear instructions of the system in the owners manual, and for this reason the insurance company saw no hope for recovery. They therefore would not attempt to pursue Subaru for any recovery or pay any additional expenses of checking the car for further defects. Insurance company just totaled the car, paid the collision claim minus deductible, and hit the customer for a chargeable accident on her record. Told her if she wanted to persue Subaru further, she was on her own.

Everyone needs to understand when to use these features, and more importantly, when to NOT use these features. Accidents can and do happen as a direct result of these perceived safety features, when the driver doesn't use them correctly.
 
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Fast Eddie B said:
Do you guys think that braking was due to ACC or did the collision mitigation system? If the latter, not driving in ACC wouldn’t have made any difference.
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I agree with @KentuckyKen that the event was the ACC. So far, every CMBS event in my car has been accompanied by dash lights. Not so with the ACC braking; it just hits the brakes hard with no dash lights when it thinks distance or closing speed is "wrong". I no longer us ACC in my car, regardless of the weather. Regular cruise control is fine with me.
 
I'm shifting into this same camp with Sandroad. I am tired of being in the right lane behind someone that exits and having the ACC slow hard thinking I am closing the distance on the exiting car. Not a close encounter from behind yet, but still not something I like.
 
I guess I tug on the left regen lever to disengage, at the same time I'm driving through an ACC autobrake (it's so automatic, I forgot that part). Mine always gives the orange brake rectangle in the driver's display, but it might be on the fast side sometimes.

ACC is a very personal choice for sure. I have a friend who won't touch regular CC and does not understand why anyone would want to use it. She is quite a good driver, but hates automation.

I'm sold on ACC since Volt gen 2 and love to use it (as appropriate by wx conditions) on the Clarity. I find the gap settings very useful to adjust to driving congestion. But, I'm always right there on top of it, and override (or, I guess disengage with the paddle) often.
 
I love ACC too and use it frequently. Once past the learning curve I can easily anticipate when the car is going to over-react to something. So I just tap the cancel button first, then resume when the danger is past. 95% of the time it’s great and I love it. 5% of the time I override what it’s going to do before it overreacts.

I have to admit Toyota’s system is far smoother and smarter than Honda’s is. Drove a RAV4 with their system and it never over reacted in situations where my Hondas with Sensing would. Its clearly a better system. As time goes in they will all improve.
 
Sandroad said:
I agree with @KentuckyKen that the event was the ACC. So far, every CMBS event in my car has been accompanied by dash lights. Not so with the ACC braking; it just hits the brakes hard with no dash lights when it thinks distance or closing speed is "wrong". I no longer us ACC in my car, regardless of the weather. Regular cruise control is fine with me.
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How do you get cruise control without ACC in the Clarity?
 
Robert_Alabama said:
I'm shifting into this same camp with Sandroad. I am tired of being in the right lane behind someone that exits and having the ACC slow hard thinking I am closing the distance on the exiting car. Not a close encounter from behind yet, but still not something I like.
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What got me is the acc will brake when im about 300 feet from a slower moving vehicle regardless of distance setting. So un nessacary. But easy to turn off acc. I just pressed and held the distance selector switch (next to the main switch) and it turned on regular cruise control.
 
ClarityBill said:
How do you get cruise control without ACC in the Clarity?
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You can disable ACC according to page 105 of the owners guide:

Switching to Standard Cruise Control
• Press and hold the Interval button.
• Cruise Mode Selected appears in the Driver Information Interface.
Press and hold the Interval button again to switch back to ACC. ACC
Mode Selected appears.
 
bpratt said:
I was driving on the freeway in a heavy rain with cruise control set on. I was driving in the right lane because I wanted to take the next exit. A large truck passed me on the left side and kicked up a large cloud of water. I guess my car thought the cloud of water was a very slow moving vehicle, so it hit the brake hard. The car behind me had to hit their brake and probably came within a couple of feet of hitting me. Once the cloud of water cleared a little, the car release the brake and continued on and left me with my heart pounding.
Click to expand...
one should never use cruise control in the rain. I think it says so somewhere in the manual
 
craze1cars said:
I love ACC too and use it frequently. Once past the learning curve I can easily anticipate when the car is going to over-react to something. So I just tap the cancel button first, then resume when the danger is past. 95% of the time it’s great and I love it. 5% of the time I override what it’s going to do before it overreacts.
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I new to ACC and would love to use your experiences to get up to speed faster. Would you be able to do short write up on the over-reacting scenarios you experience and how you override them? thanks
 
Random example I’m in center lane and car is in left lane. It decides to merge in front of me. I know darn well there is no danger but Clarity sees sudden closure of gap so I know from past experiences it’s gonna brake. I’d rather coast. So I tap tha cancel button and car coasts for a couple seconds. Then as soon as cars are going same speed again I tap the resume button. Life goes on. Bear in line I have about 100k miles of driving behind my belt with Honda Sensing on another car. So I can predict what the car is gonna do as soon as I see someone else’s turn signal. It just comes with experience.
 
Second all that. It's cruise control, not self driving. Be prepared to override at a second's notice, and learn when to safely override to work around the areas it isn't good at handling. A light accelerator tap every now and then will get it to stop slowing down when somebody is exiting in front. For all the car knows, they're slowing down in your lane, if it's an exit that just widens the lane before splitting. The car is doing the right thing based on the data available to it.
 
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