Hard-braking events as indicators of road segment crash risk • Hacker News Board

Re: Hard-braking events as indicators of road segment crash risk

#161

Post by antisthenes » Mon, Feb 09, 2026, 8:59 PM UTC

ChuckMcM wrote: post #78

mountain_peak wrote: post #46

Earlier quoted context omitted.

Maintaining a safe following distance is incredibly challenging on busy freeways where hard braking is often 'required'. Most people have likely found themselves in this situation: vehicle changes lanes in front of you; you slow down to maintain a safe following distance, another car sees a gap and changes lanes in front of you. Repeat for your entire commute. Incredibly frustrating, and I've driven all over North Am…

Okay I'm thinking of a very Shenzen kind of gizmo for your car that projects a bright red laser "keep out" box on the road in front of your car which is adjusted in size for your current speed.

Can't wait to get blinded by lasers when cars are going over bumps and speed humps.

I know you were probably writing tongue in cheek, but that is one of those "solutions" that doesn't stop bad actors and makes good actors more miserable than usual.

Re: Hard-braking events as indicators of road segment crash risk

#162

Post by Gravityloss » Mon, Feb 09, 2026, 8:59 PM UTC

mountain_peak wrote: post #46

presidentender wrote: post #20

I got one of those dongles from my insurance company that plugged into the ODB2 port and reported my driving habits. I was a bad driver. It would frequently beep at me to let me know that I had braked too hard. I was mystified. "What should I have done differently," I'd think, as I raged at the objective machine that judged me so. The next time my brother came to visit, he called mom. "Oh, and presidentender is a goo…

Maintaining a safe following distance is incredibly challenging on busy freeways where hard braking is often 'required'. Most people have likely found themselves in this situation: vehicle changes lanes in front of you; you slow down to maintain a safe following distance, another car sees a gap and changes lanes in front of you. Repeat for your entire commute. Incredibly frustrating, and I've driven all over North Am…

I live in a place that has harsh winter conditions with ice, gravel and the occasional loose tire stud flying into people's windshields, warranting frequent expensive replacements.

Somebody on the radio said that "just set the adaptive cruise control to max distance and your windshield will last way longer". It does feel overprotective at times, especially in slow and dense traffic, but I think there's a nice point in general.

Re: Hard-braking events as indicators of road segment crash risk

#163

Post by pibaker » Mon, Feb 09, 2026, 9:03 PM UTC

avidiax wrote: post #9

pavel_lishin wrote: post #4

Earlier quoted context omitted.

My mom had a device installed in her car to get a discount on her insurance, and she was always upset at the hard braking thing - whenever she did it, it was because another car was doing something unsafe that she couldn't control, like pulling out in front of her.

Some amount of that is inevitable, but there is another level of defensive driving where you anticipate poor behavior and arrange that it won't cause an accident. Have a look at a few dash cam accident videos [1]. There are many maladaptive patterns of behavior, but a frequent one that the average good driver can improve on is limiting speed on two occasions: when approaching a blind spot, and when passing stopped or…

One thing I noticed among dash cam videos is very often the person recording and publishing the video will keep on driving closely behind another car that is clearly driving erratically. Maybe he will honk, but he won't brake or leave any safety distance, and seconds later the idiot's car, which has been behaving weirdly in front of him the whole time, causes him to crash.

I realize this may come off as victim blaming, but I feel you should have an obligation to not endanger yourself even if by the laws of the road you are technically in the right. I would rather get cut off by and idiot and be at my destination thirty seconds later than having to deal with car repairs even when it is legally speaking not my fault.

Re: Hard-braking events as indicators of road segment crash risk

#164

Post by californical » Mon, Feb 09, 2026, 9:04 PM UTC

ip26 wrote: post #112

sigseg1v wrote: post #26

Earlier quoted context omitted.

Adding on to this, a common reaction I see to online videos of driving incidents is "why did this person just stop? of course you are going to crash into them. They shouldn't have stopped" and many people agreeing with it. It seems they are blind to the fact that if the following driver was using a safe following distance and speed, they should easily be able to stop, making the incident the fault of the driver follo…

Some degree of road safety depends on predictable behavior. I haven’t seen those videos, but suddenly executing a panic stop on the freeway for no good reason at all increases everyone’s risk, even if the car behind you is following at a safe distance. Obviously the following driver bears the most responsibility, but erratic drivers shouldn’t be held to be morally blameless.

> erratic drivers

People don’t usually act erratically for no reason. Maybe they suddenly stop because they see a deer sprinting towards the road off in the distance, and the person behind them didn’t see it. There are tons of reasons that look like they “erratically stop”, which are actually genuine safe behavior that the other may not know about.

Re: Hard-braking events as indicators of road segment crash risk

#165

Post by kqr » Mon, Feb 09, 2026, 9:06 PM UTC

presidentender wrote: post #20

I got one of those dongles from my insurance company that plugged into the ODB2 port and reported my driving habits. I was a bad driver. It would frequently beep at me to let me know that I had braked too hard. I was mystified. "What should I have done differently," I'd think, as I raged at the objective machine that judged me so. The next time my brother came to visit, he called mom. "Oh, and presidentender is a goo…

Not only are you less likely to crash -- you're less likely to cause a crash ten cars behind you.

This diagram changed how I think about following distance: https://entropicthoughts.com/keep-a-safe-following-distance

Re: Hard-braking events as indicators of road segment crash risk

#166

Post by bloomingeek » Mon, Feb 09, 2026, 9:12 PM UTC

mountain_peak wrote: post #46

presidentender wrote: post #20

I got one of those dongles from my insurance company that plugged into the ODB2 port and reported my driving habits. I was a bad driver. It would frequently beep at me to let me know that I had braked too hard. I was mystified. "What should I have done differently," I'd think, as I raged at the objective machine that judged me so. The next time my brother came to visit, he called mom. "Oh, and presidentender is a goo…

Maintaining a safe following distance is incredibly challenging on busy freeways where hard braking is often 'required'. Most people have likely found themselves in this situation: vehicle changes lanes in front of you; you slow down to maintain a safe following distance, another car sees a gap and changes lanes in front of you. Repeat for your entire commute. Incredibly frustrating, and I've driven all over North Am…

Tailgating is against the law. Tailgating causes hard braking.

I recently pulled my travel trailer from OK to Charleston, SC and back. I never drive over 65 MPH for safety and MPG reasons. I always stay in the right hand, slow lane except if I have to take a left lane exit. Since I was always driving slower then everyone else, not once did I have to hard brake. Tailgating is a choice and a dangerous one.

I was never honked at, even by the crazy semi truck drivers.

Re: Hard-braking events as indicators of road segment crash risk

#167

Post by rconti » Mon, Feb 09, 2026, 9:12 PM UTC

mountain_peak wrote: post #46

presidentender wrote: post #20

I got one of those dongles from my insurance company that plugged into the ODB2 port and reported my driving habits. I was a bad driver. It would frequently beep at me to let me know that I had braked too hard. I was mystified. "What should I have done differently," I'd think, as I raged at the objective machine that judged me so. The next time my brother came to visit, he called mom. "Oh, and presidentender is a goo…

Maintaining a safe following distance is incredibly challenging on busy freeways where hard braking is often 'required'. Most people have likely found themselves in this situation: vehicle changes lanes in front of you; you slow down to maintain a safe following distance, another car sees a gap and changes lanes in front of you. Repeat for your entire commute. Incredibly frustrating, and I've driven all over North Am…

I find it quite easy to hold/manage a tight space that people won't cut into, and don't have to brake hard, because I look ahead.

To be sure, it's more mentally taxing to hold a tight gap, so it's not something you want to do all the time, but it's fine.

Re: Hard-braking events as indicators of road segment crash risk

#168

Post by stevage » Mon, Feb 09, 2026, 9:15 PM UTC

Gravityloss wrote: post #162

mountain_peak wrote: post #46

Earlier quoted context omitted.

Maintaining a safe following distance is incredibly challenging on busy freeways where hard braking is often 'required'. Most people have likely found themselves in this situation: vehicle changes lanes in front of you; you slow down to maintain a safe following distance, another car sees a gap and changes lanes in front of you. Repeat for your entire commute. Incredibly frustrating, and I've driven all over North Am…

I live in a place that has harsh winter conditions with ice, gravel and the occasional loose tire stud flying into people's windshields, warranting frequent expensive replacements. Somebody on the radio said that "just set the adaptive cruise control to max distance and your windshield will last way longer". It does feel overprotective at times, especially in slow and dense traffic, but I think there's a nice point i…

Wow, I didn't know that was a thing. Been driving nearly 30 years, and never had a windshield chip.

Re: Hard-braking events as indicators of road segment crash risk

#169

Post by rconti » Mon, Feb 09, 2026, 9:16 PM UTC

This is a great use of this technology. In aggregate, these hard braking events _do_ tell us about road design issues. They also tell us about problematic drivers, in aggregate.

I'll never use one of these dongles, though, because I don't want my every move second-guessed. There's nothing _inherently_ dangerous about isolated hard braking or cornering or acceleration events. It all depends on context. Am I braking hard to avoid an obstacle or mistake by another driver? Is there someone behind me that's likely to rear-end me, or am I in the middle of a highway in the desert? Did I just replace my brake pads and I'm bedding in the new pads?

I don't want to have to worry about whether I've used up my invisible quota before the algorithm decides I should be moved into a more expensive insurance bracket.

Re: Hard-braking events as indicators of road segment crash risk

#170

Post by rconti » Mon, Feb 09, 2026, 9:17 PM UTC

bloomingeek wrote: post #166

mountain_peak wrote: post #46

Earlier quoted context omitted.

Maintaining a safe following distance is incredibly challenging on busy freeways where hard braking is often 'required'. Most people have likely found themselves in this situation: vehicle changes lanes in front of you; you slow down to maintain a safe following distance, another car sees a gap and changes lanes in front of you. Repeat for your entire commute. Incredibly frustrating, and I've driven all over North Am…

Tailgating is against the law. Tailgating causes hard braking. I recently pulled my travel trailer from OK to Charleston, SC and back. I never drive over 65 MPH for safety and MPG reasons. I always stay in the right hand, slow lane except if I have to take a left lane exit. Since I was always driving slower then everyone else, not once did I have to hard brake. Tailgating is a choice and a dangerous one. I was never…

Even that can be tricky, with the indecisive behavior people use when merging.