Under the influence of adaptive cruise control

[Puyapim]

Portland or Seattle?

Seattle. Portland can be tough as well but I usually take the 205 when I’m going through.

 

[Ricsta]

Sounds like Tesla's tech is still beta release and buggy

I agree. In another accident where the Tesla autopilot hit a trailer perpendicularly as it entered an intersection, Tesla released a statement reiterating that customers are required to agree that the system is in a "public beta phase" before they can use it. I think they also tweaked the software after that accident.

 

[shadonoz]

There was an interesting article in local motoring press that I read a couple days ago re this.

You didn't click the link that started this thread, did you? (lol2)

Or is your memory as bad as mine? (rofl2)

 

[Moonlighter]

You didn't click the link that started this thread, did you? (lol2)

Or is your memory as bad as mine? (rofl2)

Oops, no. Post deleted.

 

[7eregrine]

I don't see any advantage to travelling close cruising when you don't have too, so use a big gap between the car in front.
If someone fills my gap I just lift off and get it back.

Its the most effective way to save braking and fuel, and allows more reaction time.

Agree. The CX-5 braking distance is 180 feet.
15 feet is to close.
Read a great article a few years ago re: if every car on the highway gave the car in front of it 4 car lengths, congestion would drop significantly. I can't find it anymore. But in congestion if everyone is following closely, as they do, even if you just tap your brake and it doesn't engage, the guy behind you will apply the brake. And the guy behind him. And the guy behind him. Pretty soon it's bumper to bumper. If you leave enough space so that someone can get in front of you without making you apply the break...

 

[Xeler8ing]

Travelling too close could be classified as tailgating

 

[bmninada]

You are correct! But I could swear that I can't ever get lower than 2 bars at my normal 74 mph. I'll have to check next time I'm on the highway.

But that diagram seems to be wrong. It indicates that at 50 mph: 4 bars = 2.2 sec, 3=1.8, 2=1.3, and 1 bar=1.1 sec. It seems to me that the "headway" is much greater than that, but I rarely set it at 50. So maybe it's not a linear time relationship after all. Maybe it's got a lower limit [longer time/distance per bar] at higher speeds.

Or maybe I'm just confused. Wouldn't be the first time.

Hey Anchorman, got any tech docs on this topic?

And thanks for making me go to my OM to verify. I didn't realize you could change the set speed +/- 5 mph with a long press.

I learn something new every day from hanging around this group!

Short press: +/- 1 mph.
Long press: +/- 5 mph - but be very careful. That thing jumps fast. I had a case when jumped from 55 to 90 before I realized it.
Best part (for me): You can accelerate when changing/over-taking/etc. ; leave the gas and the car drops back to set cruise. With adaptive into the mix; its awesome.

 

[bmninada]

Travelling too close could be classified as tailgating

And problem #2 - too small a gap ++ the fact you're in cruise will definitely mean foot NOT on gas. Sometimes even a 50 milliseconds make a huge difference. Foot going up towards the brake, i.e. from its cruise position. Also human nature will be to be a tad less attentive now that car's cruising.
Finally, I have personally been in pickups where the driver was PURPOSEFULLY sudden braking when he noticed someone tail-gating him.

 

[Anchorman]

You are correct! But I could swear that I can't ever get lower than 2 bars at my normal 74 mph. I'll have to check next time I'm on the highway.

But that diagram seems to be wrong. It indicates that at 50 mph: 4 bars = 2.2 sec, 3=1.8, 2=1.3, and 1 bar=1.1 sec. It seems to me that the "headway" is much greater than that, but I rarely set it at 50. So maybe it's not a linear time relationship after all. Maybe it's got a lower limit [longer time/distance per bar] at higher speeds.

Or maybe I'm just confused. Wouldn't be the first time.

Hey Anchorman, got any tech docs on this topic?

And thanks for making me go to my OM to verify. I didn't realize you could change the set speed +/- 5 mph with a long press.

I learn something new every day from hanging around this group!

Got this one!

 

[Xeler8ing]

And problem #2 - too small a gap ++ the fact you're in cruise will definitely mean foot NOT on gas. Sometimes even a 50 milliseconds make a huge difference. Foot going up towards the brake, i.e. from its cruise position. Also human nature will be to be a tad less attentive now that car's cruising.
Finally, I have personally been in pickups where the driver was PURPOSEFULLY sudden braking when he noticed someone tail-gating him.

Indeed. Some people's reaction time is not very good

 

[shadonoz]

Agree. The CX-5 braking distance is 180 feet.
15 feet is to close.

Braking distance is speed dependent, so that is a meaningless statement without a speed specified. Car and Driver's tests @70 mph yielded 182 ft, so that's probably what you're talking about.

What's 15 feet got to do with anything being discussed here?

If you're talking about stopping distance, you have to include reaction time, too. Reaction time + braking time = stopping time. Times can be converted to distance when speed is specified.

But why talk about distance? It's very hard to judge following distances. The only reliable way for a driver to judge following distance is to measure time. Then it's NOT speed dependent. We all know that radar measures time, and not distance, right? It then calculates distance from the time observed.

The universally accepted rule of thumb is that 2 seconds is a safe following distance. That includes reaction time AND braking time.

What I'm trying to figure out is what time the MRCC is using to control headway under each of the four settings. If I keep a safe time behind the car ahead, then I am by definition following at a safe distance, because I have good reaction time. And you can be confident that when they determined that 2 seconds was a safe following time, they took into account that some people have slower reaction times.

The numbers in the manual don't make sense.

 

[shadonoz]

Travelling too close could be classified as tailgating

Tailgating is defined as travelling too close!

But who's talking about tailgating? Do you think Mazda would allow MRCC to permit tailgating? No way!

 

[shadonoz]

Short press: +/- 1 mph.
Long press: +/- 5 mph - but be very careful. That thing jumps fast. I had a case when jumped from 55 to 90 before I realized it.
Best part (for me): You can accelerate when changing/over-taking/etc. ; leave the gas and the car drops back to set cruise. With adaptive into the mix; its awesome.

Got to be attentive at all times !

Even standard CC allows you to accelerate and then will resume the set speed as long as you don't touch the brake (or cancel it). It's always been like that.

But I agree, the adaptive is absolutely awesome!!

 

[shadonoz]

And problem #2 - too small a gap ++ the fact you're in cruise will definitely mean foot NOT on gas. Sometimes even a 50 milliseconds make a huge difference. Foot going up towards the brake, i.e. from its cruise position. Also human nature will be to be a tad less attentive now that car's cruising.
Finally, I have personally been in pickups where the driver was PURPOSEFULLY sudden braking when he noticed someone tail-gating him.

Where do you put your foot when using CC? I bet not on the gas. Sounds like that argument suggests one should never use cruise. Unacceptable!

Drivers who respond to tailgaters by braking hard are a real hazard, and frankly, stupid.

There's a much better way to respond to tailgaters. TAP the brakes, light up those brake lights, BUT DON'T APPLY THE BRAKES. The tailgater will either back off or s*** their pants or both. DO NOT DO THIS WHEN THE TAILGATER HAS SOMEONE TAILGATING THEM!!!!

Then again, you never know when the other driver is having a bad day and packing heat. It happens.

 

[shadonoz]

Got this one!

Thanks!

 

[Puyapim]

Braking distance is speed dependent, so that is a meaningless statement without a speed specified. Car and Driver's tests @70 mph yielded 182 ft, so that's probably what you're talking about.

What's 15 feet got to do with anything being discussed here?

If you're talking about stopping distance, you have to include reaction time, too. Reaction time + braking time = stopping time. Times can be converted to distance when speed is specified.

But why talk about distance? It's very hard to judge following distances. The only reliable way for a driver to judge following distance is to measure time. Then it's NOT speed dependent. We all know that radar measures time, and not distance, right? It then calculates distance from the time observed.

The universally accepted rule of thumb is that 2 seconds is a safe following distance. That includes reaction time AND braking time.

What I'm trying to figure out is what time the MRCC is using to control headway under each of the four settings. If I keep a safe time behind the car ahead, then I am by definition following at a safe distance, because I have good reaction time. And you can be confident that when they determined that 2 seconds was a safe following time, they took into account that some people have slower reaction times.

The numbers in the manual don't make sense.

Road conditions have to be part of the equation. If you have your MRCC set to the minimum distance for dry roads, is it safe for wet roads? I don’t think these systems are that smart yet or maybe I’m wrong?

 

[Xeler8ing]

Tailgating is defined as travelling too close!

But who's talking about tailgating? Do you think Mazda would allow MRCC to permit tailgating? No way!

No but you stated you wanted it to be closer right (uhm)

 

[Puyapim]

Where do you put your foot when using CC? I bet not on the gas. Sounds like that argument suggests one should never use cruise. Unacceptable!

Drivers who respond to tailgaters by braking hard are a real hazard, and frankly, stupid.

There's a much better way to respond to tailgaters. TAP the brakes, light up those brake lights, BUT DON'T APPLY THE BRAKES. The tailgater will either back off or s*** their pants or both. DO NOT DO THIS WHEN THE TAILGATER HAS SOMEONE TAILGATING THEM!!!!

Then again, you never know when the other driver is having a bad day and packing heat. It happens.

Or, as the family suv had many years ago, a nice long tow hitch with a hook welded on it. Anyone that hit that would know it right away.

 

[shadonoz]

Road conditions have to be part of the equation. If you have your MRCC set to the minimum distance for dry roads, is it safe for wet roads? I dont think these systems are that smart yet or maybe Im wrong?

True! Conditions, car, driver, and the immediate situation must all be taken into account at all times.

Apparently, it DOES take some road conditions into account. See the block diagram in MRCC.pdf.

Of course, that doesn't mean it's smart enough to be effective! That was the basic premise of the article that started this thread.

 

[Puyapim]

True! Conditions, car, driver, and the immediate situation must all be taken into account at all times.

Apparently, it DOES take some road conditions into account. See the block diagram in MRCC.pdf.

Of course, that doesn't mean it's smart enough to be effective! That was the basic premise of the article that started this thread.

I did check out the pdf. Something like having your lights on or windshield wipers running could tell the system to back off a bit more but I didn’t see anything like that there. It’s a thought though.