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Hard-braking events as indicators of road segment crash risk

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

#541

Post by adolph »

ehnto wrote: post #326
maerF0x0 wrote: post #219

Earlier quoted context omitted.

It's frustrating because someone is taking your safety buffer as their opportunity to travel faster. And it results in you having to travel slower and slower to maintain the gap that is constantly consumed, tragedy of the commons style, by opportunists.

Slow down a bit to create another buffer. You can even do this before they have merged, as part of the bit where you allow them to safely merge. I think if you reflect a bit you'll find you are being the same kind of person as them, if you are getting angry that you have to slow down and give up space for someone else. I understand some people can be aggressive though, that can be frustrating regardless of the outcom…

  >> It's frustrating because . . .
  > Slow down a bit to create another buffer
  > I think if you reflect a bit you'll find
The parent post does return to the psycho-emotional layer of the problem but on the whole the exchange brings to mind the "two movies, one screen" model of perennial problems. In many of the comments here some people emphasize the problem in terms of physics and some see the problem in terms of psychology (both have overlap and are valid).

A third perspective may be "game theory." I think the Prisoner's Dilemma [0] could explain some aspects of the physical/mental problem. In the set below, Driver A's strategy isn't dependent on a singular predictable Driver B but all drivers that may perform the role of Driver B during the course of a commute.

  Agent       Cooperate     Defect
  Driver A    leaves space  doesn't
  Driver B^n  merge         stay
Leaving aside all times in which a Driver B must merge, such as lane ending zippers or merging to approach an exit lane, Driver B merges because there is some advantage to being in the lane of Driver A. If Driver A maintains space they will not just lose to one Driver B but to all Driver Bs.

I conjecture that this is a collective action problem and that above a certain traffic saturation point there must be a social taboo against changing lanes.

This is not to claim that individual perspective shifting is not important. I am reminded of Foster Wallace's Kenyon address "This is Water," [1] quoted below. However, the task of changing individual perspectives is vastly higher energy than the creation of a social taboo, which is why purity codes and other social inhibitors are so prevalent.

  If I choose to think this way in a store and on the freeway, fine. Lots of us 
  do. Except thinking this way tends to be so easy and automatic that it 
  doesn’t have to be a choice. It is my natural default setting. [...]
  
  The thing is that, of course, there are totally different ways to think about 
  these kinds of situations. [...] [Maybe] the Hummer that just cut me off is 
  maybe being driven by a father whose little child is hurt or sick in the seat 
  next to him, and he’s trying to get this kid to the hospital, and he’s in a 
  bigger, more legitimate hurry than I am: it is actually I who am in HIS way.
0. https://en.wikipedia.org/wiki/Prisoner's_dilemma

1. https://fs.blog/david-foster-wallace-this-is-water/

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

#542

Post by alt227 »

array_key_first wrote: post #534
alt227 wrote: post #460

Earlier quoted context omitted.

IMO there is nothing worse than drivers on highways who think that by leaving bigger gaps and slowing less rapidly they are 'smoothing' out the traffic and helping the whole road run better. You are not, you are just making the whole road run slower and taking up more space for yourself on a crowded road.

This is untrue, there have been studies done that discovered the primary cause of traffic is following too close. Following further away really does reduce the amount of traffic. It seems unintuitive, but consider: every time you brake, the person behind you has to brake a teensy bit longer. And then the person behind them, and behind them. That little bit of extra time accumulated quickly and grinds the highway to a…

Exactly, and that same theory also applies to long slow breaking as well.

What you are refering to is the well known phenomenon of traffic waves or phantom jams. The UK has all but eliminated them with variable speed limits without the need to make every leave half a mile gap between each car.

https://nationalhighways.co.uk/road-safety/variable-speed-li...

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

#543

Post by hydrogen7800 »

b40d-48b2-979e wrote: post #467
alt227 wrote: post #457

Earlier quoted context omitted.

Why jump to cities? Low speed traffic in cities is not the main location of car collisions. The main issue is highways and rural roads.

The main issue is highways and rural roads. Source? I'd wager most accidents happen where the most people are. Cities.

> I'd wager most accidents happen where the most people are. Cities.

Sure, in absolute numbers. But..

In the US, highest deaths per 100M vehicle miles:

1.79 - Mississippi

1.73 - Arizona

1.72 - South Carolina

And the lowest:

0.56 - Massachusetts

0.70 - Minnesota

0.78 - New Jersey

Or, highest per 100,000 population:

25 - Mississippi

25 - Wyoming

21 - New Mexico

Lowest per 100,000:

4.9 - Massachusetts

5.7 - New York

6.5 - New Jersey

Maybe the average MS driver drives 3-5x as many miles as the average MA driver? I doubt it. Something else happening there.

https://www.iihs.org/research-areas/fatality-statistics/deta...

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

#544

Post by spacecadet »

whynotmaybe wrote: post #497
spacecadet wrote: post #474

Defensive driving. Two hands, eyes on the "road", not caring about fools and maintaining safe distances. You have all the time in the world... I Recommend taking your car to a HPDE event, sometimes insurance will discount you for this. In this case, hard braking, is you just not knowing anything about your car or the cars around you... I barely use my brakes, but I also drive manual... Id say learn engine braking but…

https://donmcminn.com/2020/02/we-judge-ourselves-by-our-inte...

Nice, but... We live in a world with shared roads... I think a much worse outcome is unfolding as we sell self-driving/assisted EVs to people with little to no real driving experience, while also not upgrading the roads, the laws, and driving education.

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

#545

Post by direwolf20 »

maerF0x0 wrote: post #513
direwolf20 wrote: post #433

Earlier quoted context omitted.

You mean 20 people who were trying to merge finally get to merge because someone came past who wasn't a massive asshole?

To be completely clear the conversation is entirely not about zipper merging, but about people who are using safety gaps as opportunities for them to traffic weave attaining a faster than average travel speed at the cost of every one else's average travel speed and safety

That sounds like a recipe to crash into someone. Let natural selection work.

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

#546

Post by drewgross »

crazygringo wrote: post #331
ehnto wrote: post #326

Earlier quoted context omitted.

Slow down a bit to create another buffer. You can even do this before they have merged, as part of the bit where you allow them to safely merge. I think if you reflect a bit you'll find you are being the same kind of person as them, if you are getting angry that you have to slow down and give up space for someone else. I understand some people can be aggressive though, that can be frustrating regardless of the outcom…

I don't think you're understanding. The point is that 20 people in a row will take advantage of your buffer to slow you down again and again and again, which makes you get to your destination later... because they're being selfish to get somewhere faster, and you're not so you get to where you're going slower . We're not talking about where they're changing lanes to take the next exit. We're talking about where your…

If 20 people take advantage of your buffer, then you are delayed by a distance of 20 vehicle-lengths + 20 follow-distances. This is about 1000 meters, a distance which you can travel in about 45 seconds. So the net effect of all 20 people merging in front of you is less than a minute delay on your trip. Unless there is an almost constant stream of people merging in front of you, this isn't adding up to more than a percentage point of two of your whole trip.

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

#547

Post by alt227 »

asdff wrote: post #293
OneOffAsk wrote: post #140

Aim to make the road laminar. Every time you hard brake, you're causing the milk jug to glug, making a ripple of entropy as momentum turns to heat from your brakes and those behind you, sometimes in perpetuity. I learned this while doing a 1.5hr daily commute in a Subaru with a clapped out manual transmission. I wanted to conserve energy shifting, but realized I was now participating in large choreographed dance of "…

https://www.youtube.com/watch?v=Suugn-p5C1M This is the natural response of tapping the brakes for any slowdown: people naturally over compensating and chain reactions happening behind them. This video shows how stop and go traffic forms and snowballs with no real impetus beyond mis estimated follow distance.

What this video also shows is that if people pull off more or less at the same time and speed of the car in front then this is a complete non issue. Unfortunately most people are unable to watch a few cars ahead and be ready to pull of when the car in front does, and so we have this situation where each car takes around 5-10 seconds to pull away. multiply this by hundreds or thousands of cars and you end up with a phantom traffic jam.

I always pull away at the same speed as the car in front of me and maintain the same distance as when we were stopped. It is very easy to do and completely eliminates traffic build up if multiple people do it at the same time.

This is the same reason that we have amber lights on traffic lights, so that the drivers have time to get into gear and start pulling away so that when the light goes green they are imediately travelling through it, causing no excess traffic build up at the lights. Again unfortunately people dont concentrate when they are stopped at lights and so you have the situation where they see the light go green and then proceed to start changing into gear and remove the handbrake. By the time they are moving through the green light, they have already taken 10-20 seconds of green light time, eating well into the time alotted for cars to be travelling across the junction.

The only thing which will solve this is driverless cars, meaning that the cars can all talk to each other and move at the same time like a chain. I welcome this advancement to elimante human error in driving and get rid of traffic jams for good.

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

#548

Post by littlestymaar »

hydrogen7800 wrote: post #543
b40d-48b2-979e wrote: post #467

Earlier quoted context omitted.

The main issue is highways and rural roads. Source? I'd wager most accidents happen where the most people are. Cities.

> I'd wager most accidents happen where the most people are. Cities. Sure, in absolute numbers. But.. In the US, highest deaths per 100M vehicle miles: 1.79 - Mississippi 1.73 - Arizona 1.72 - South Carolina And the lowest: 0.56 - Massachusetts 0.70 - Minnesota 0.78 - New Jersey Or, highest per 100,000 population: 25 - Mississippi 25 - Wyoming 21 - New Mexico Lowest per 100,000: 4.9 - Massachusetts 5.7 - New York 6.5…

Fortunately deaths are only a fraction of the accidents though, and it's not even necessarily the kind of accident that bothers insurance companies the most as long as the driver only kills himself.

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

#549

Post by LazyMans »

alt227 wrote: post #542
array_key_first wrote: post #534

Earlier quoted context omitted.

This is untrue, there have been studies done that discovered the primary cause of traffic is following too close. Following further away really does reduce the amount of traffic. It seems unintuitive, but consider: every time you brake, the person behind you has to brake a teensy bit longer. And then the person behind them, and behind them. That little bit of extra time accumulated quickly and grinds the highway to a…

Exactly, and that same theory also applies to long slow breaking as well. What you are refering to is the well known phenomenon of traffic waves or phantom jams. The UK has all but eliminated them with variable speed limits without the need to make every leave half a mile gap between each car. https://nationalhighways.co.uk/road-safety/variable-speed-li...

We have variable speed limits on parts of our roads. People commonly exceed the stated limit by 20+ mph since they're used to "full speed" and ignore the instances where it's being reduced.

I welcome our future robot car overlords where all of these problems should in theory be greatly reduced or eliminated entirely.

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

#550

Post by lowercased »

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…

I've got a tracker and it keeps showing "sharp turn" right in my neighborhood. It's counting the turn in to my driveway - a 90 degree turn - as a "sharp turn". It doesn't seem to matter how slow I go - I'm not racing in to the driveway - generally slowed to walking speed by that point - and I'm still getting 'dinged' every day for this.
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