This is about human lives. Once you eliminate birth-defects, car accidents are the leading cause of death for people under 35. Particularly for young kids, who obviously aren't driving.
Car accidents kill 34,000 Americans per-year. That's like if 9/11 happened once a month every year.
And speed matters. Stopping distance and kinetic energy go up with the square of velocity. A pedestrian hit by a car going 20 mph will almost certainly live. A person hit by a car going 40 mph will almost certainly die.
Before 1995, the federal government restricted speed limits to 65mph and lower (and prior to 1987, 55mph and lower). When those limits were raised or lifted, those opposing the change howled about how many additional Americans would die with higher speed limits.
The decline in auto fatalities (and pedestrian fatalities) has continued, even as speed limits went up dramatically in many states.
Correct! The 55mph law was first started during the gas crisis of the 70s. Its impact on traffic safety has been argued back and forth ever since, but so far there is zero concrete evidence that the increase in speed limits has caused a likewise increase in fatalities. (I have heard some good-sounding arguments that 55mph on long stretches of road is actually more dangerous than 70mph on the same, but I cannot find any studies to back that up, either.)
I'm curious how that number has changed for people in the cars versus people hit by the cars.
I would imagine that the rate has dropped precipitously for people in cars, but has been rising for those outside the cars.
FWIW I've been hit twice as a bicyclist, both were the fault of the driver. One turned into me while I was in the bike lane and the other tried to overtake me and clipped the front of my bike dragging it under the front tire. I was very lucky both times.
Driving like an idiot while speeding causes accidents. Speeding itself does not cause accidents.
Speeding does mean that in the event of an accident, the outcome is likely to be worse for all involved.
And there's no excuse for speeding in a residential area, or anywhere you might see pedestrians (or expect them and be unable to see them). This qualifies as "driving like an idiot".
I'd like to clarify a bit on "speeding itself does not cause accidents". You're mostly right, but it's not strictly true. There are realistic cases where speeding itself will cause a crash, such as poor visibility where you're driving too fast to stop within the distance you can see, driving fast enough to lose control on poor surfaces, being too fast to take a curve, and such.
I don't know how significant it is, I just want to say this because people shouldn't think that they can go as fast as they want as long as they drive well. Sometimes you simply have to slow down.
(I got reminded of this last year when I wrecked my car by hydroplaning on the highway. Technically I was within the posted speed limit, but clearly I was going too fast for conditions. Speed definitely caused the accident unless you want to blame the highway department for poor drainage or mother nature for the weather. Which, of course, I do, but I still should have gone slower.)
> to stop within the distance you can see, driving fast enough to lose control on poor surfaces, being too fast to take a curve, and such.
Agreed, but I classify that as "driving like an idiot" - driving too fast for conditions is in a category beyond speeding. Part of driving well is knowing - outside of concerns for a ticket - when it's possible to speed safely (and by how much), and when it's not.
I doubt how anybody can claim they're "driving safely" when the only observer is oneself and there is no baseline to compare against. This is about as statistically meaningful as people buying homeopathy stuff because they "know" it works.
>I doubt how anybody can claim they're "driving safely" when the only observer is oneself and there is no baseline to compare against.
Don't we all get observed and evaluated by a driving instructor before being licensed (think about what that word means) to drive? I'd say that meets your criteria
In theory, yes. In practice, driving instruction and testing in the US is ludicrously inadequate. The driving test here is little more than making sure you're capable of writing your own name.
This attitude is exactly why I think that vehicular assault and homicide should be prosecuted even if alcohol isn't involved. Every jerk with a fast car thinks he's god's gift to driving and the rules shouldn't apply to him. Then when there's a crash it's described as an accident. In the overwhelming number of cases it wasn't an accident, it was negligence, often criminal negligence.
You want to drive fast go to a track, on the public roadways follow the damn law.
> You want to drive fast go to a track, on the public roadways follow the damn law.
The "jerks with fast cars" group that you're targeting is breaking the same laws that 99% of other drivers break. In some ways, other drivers are worse.
Nobody obeys posted speed limits, except on side streets. Very few people pay enough attention to their driving; they're mostly talking on cell phones or daydreaming or talking to a passenger. Jerks with fast cars, at least, are focused on driving. Collisions at those speeds may not be survivable, but I don't want to get into any collision at highway speeds; their driving patterns are more predictable, and I prefer them over distracted or ADHD drivers who make quick lane changes without proper awareness.
Yeah. I don't generally care too much if somebody's going a bit fast, so long as they aren't driving erratically. What does cause a lot of swearing and the occasional close call:
- People merging on or off the highway at unsafe speeds (usually, too slow), without looking and picking a spot in traffic to merge into;
- People "being polite" at intersections;
- People not using their turn signals;
- People cutting in traffic, swerving, cutting off other cars, tailgating, or otherwise driving too aggressively;
- People trying to beat the light;
- People talking on the damn phone -- I don't care who you are, you can't do that and pay full attention to the road at the same time;
- People daydreaming, hanging out with their passengers, otherwise not paying attention to traffic both ahead and behind them.
Fast drivers are almost the least offensive nuisance on the road.
Sure those other guys are in the wrong too. My point is that killing someone because you didn't want to take a cab home is horrific but so to is killing someone because it's fun to drive fast, to shave 15 minutes off a four hour trip, because you just have to know right now who won the packers game, or because the kids are bickering in the back seat. The resulting injury and death aren't the result of accidents but crimes. Crimes rather more serious than possessing a few grams of cocaine base I might add.
> ...but so to is killing someone because it's fun to drive fast...
How often do you think this happens?
The NHTSA has a talking points primer for prosecutors with a few numbers on unsafe driving. The numbers are outdated, but they give us something to work with: 13,000 people were injured or killed between 1990 and 1997 because of aggressive driving -- a broad category that includes not just speeding, but also tailgating, lane changing, and improper passing.
That's 2,000 people per year for that period, and since that period, the number of vehicular fatalities has fallen off of a cliff: "The 32,367 traffic fatalities in 2011 were the lowest in 62 years" (http://en.wikipedia.org/wiki/List_of_motor_vehicle_deaths_in...).
Every single time I have looked, I have been unable to find any evidence whatsoever that doing 85mph on the freeway in safe conditions significantly increases the chances of injuring yourself or others vs. doing 70 in the same conditions.
Yet speeding is this one traffic behavior that people really seem to get riled up about.
I have a suspicion that the actual reasons for this are that speeders tend to be unrepentant, and that it's a flagrant breaking of the law -- it's visible and people notice it more than possibly any other driving habit. Those things together seem to trigger some people's moral crusader button.
I won't quite go so far as to defend speeding. I'm never the fastest driver on the road (anymore). But if someone really wants to get going about the dangers of speeding, I'll be happy to point out all of the other driving behaviors that are at least as dangerous -- probably at least one or two of which the person themselves is guilty of, as we all are.
Remember to properly keep apart the annoyances vs. the dangers in your head. People being overly "polite" in intersections are merely annoying. People on the phone are going to commit negligent homicide.
As a driver, it's easy to mentally group all the frustrations on the road together, when some are just annoying and some are potentially lethal.
>Jerks with fast cars, at least, are focused on driving.
Maybe they are, maybe they aren't, but I doubt speed is a good predictor of attention or skill. Poor drivers have a greater risk of causing an accident than skilled drivers at all speeds. We still punish skilled drivers the same as poor drivers because it's hard to differentiate between them. Take a driver of unknown skill who's driving 1 standard deviation above the speed limit. He could be above-average, and be just as safe as an average driver going the speed limit. He could also be below-average and believe he's safe - but would actually need to go one standard deviation slower than the speed limit to match the safety limit of the skilled driver. So, we punish them both the same, because we can't know.
This just raised the question in me how efficient speed limits are. Being from Germany with no speed limit on the Autobahn I expected to see at least a slightly higher number of road fatalities in Germany. A quick look at Wikipedia confirmed that speed limits in the USA and in Germany are roughly comparable besides the unlimited Autobahn where people driving at 130 mph and more is not uncommon. [1]
USA Germany
Towns 25 – 45 majority 31, some 18 - 43
Single Carriageway 55 62
Dual Carriageway 65 - 80 unlimited, 80 advisory
To my surprise I found the following numbers for road fatalities per million inhabitants in 2010. [2]
USA 105
Germany 45
Any ideas how this could be explained? Could it matter that Germany is way smaller and the way to the next hospital is often shorter?
More likely it's the lower number of driving-hours per-person. The longer you drive, the greater the odds that something can go wrong. Germany, like most of Europe, has dense old urban cities and good transit infrastructure compared to American suburban sprawl. That means the average German doesn't spend as much time behind the wheel, if at all.
I wouldn't be surprised if Germany is substantially more dangerous per-driving-kilometer than the USA, but with far fewer driving-kms per person.
Also, remember that in many locations the "speed limit" isnt' really the defining thing that controls how drivers handle the road - many dense twisty urban environments are tight-enough to navigate that drivers instinctively take it slow and never even approach the speed limit. This tremendously reduces the odds of a fatality, although it does make minor scrapes pretty common.
You might be spot on - 7,500 kilometers per capita and year in Germany (2011) and 15,000 kilometers per capita and year in the USA (2013). This gives the same ratio as the road fatalities do.
Delta-V, delta-t, crumple zone energy absorption and airbag/safety device deceleration capability matter.
The only energy that can do damage starts with the difference in speed between vehicles. Then you have to take into account how much time it takes for the difference in speed to reach zero (that's the delta-t). This is a combination of braking (if any), grinding, sliding (tires sideways, rubbing against barriers, etc.) and crumple-zone deformation. And then you have safety devices such as airbags and seat-belts which are mostly about reducing the rate of deceleration.
Of course, initial velocity is important. However, focusing on that alone, I think, is focusing on the wrong variable.
Road conditions, for example, are crucial. I've ridden in taxis in Munich at 180 mph. The roads and traffic supported it. No issues. On the other hand, a couple of months ago I was on a BMW on the north-bound 5 fwy just before the Grapevine. I started a lane change when a crack/level difference between the lanes grabbed the tires. This caused a violent unintended lane change. Had my reflexes been any slower or had another car been there it could have been a horrible accident. I wasn't going much faster than 60 or 70 (I was about to get off the freeway to get gas). And, BTW, this is a section of the 5 that was repaired under the American Reinvestment (...) act. Well, they actually managed to cause more damage rather than repair the road. On this section of the 5 it feels like you could loose you kidneys even while riding in a minivan.
The people you run into may not have crumple-zones. Anywhere but the interstates/expressways you have to consider pedestrians as well. Even rural highways have pedestrians and cyclists.
Even on the interstate, there are road workers, tow-trucks, and (ironically) police-officers pulled over. For them? Delta-V is just V. And they do have to get out of their vehicles to do their work, so crumple zones are irrelevant too.
And this isn't hypothetical - accidents when pulled-over on highways are a major cause of death for all of those professions.
There's a fine balance here; speed isn't necessarily a problem, but speeding in the wrong places/at the wrong times. It's all about driving to the given conditions, which sadly many people do not do.
Speeding in a residential area is a lot worse, for the reason you described. New York City's speed limit of 30 is way too high (should be 20, without the 10mph tolerance). Most highways are underposted and should be 70-90.
Bizarrely, 40mph in a residential zone is a minor offense while 100mph on the freeway (which isn't exactly good, but not as dangerous as it sounds with a good car) with zero traffic can cost you your license in almost any state, and put you in jail in some.
The difference between a 60mph collision and a 100mph collision is significantly larger than the difference between a 20mph collision and 30mph collision.
In fact, with a lot of today's technology, a 20mph collision can be avoided by collision detection systems... and 30mph collisions are effectively transformed into 5mph collisions automatically.
But nothing is going to save your life from a 100mph collision.
Formula One drivers have HANS to prevent their necks from snapping in half in those crashes.
Beyond just roll cages and crumple zones... Formula One drivers have far more restrictive seatbelts and safety measures than the typical driver.
The fatality rate for the typical on-the-road driver reaches ~100% at 65mph collisions. With racing-level safety equipment and car design... sure, it can get better. But that sort of stuff is irrelevant from a public safety perspective.
"Velocity Change and Fatality Risk in a Crash–A Rule of Thumb" by Joksch. When collisions result in a Delta-V of 65mph, collisions are on the order of 70% fatal.
The fitted curve predicts the fatality rate to be ((delta-v / 71) ^ 4), suggesting a 100% death rate at 71mph.
Dropping down to 65mph drops your fatalities to 70%. Dropping down another 5mph to 60mph drops you to 50% fatality rate. The 5mph after that is a 36% chance of fatality.
So the 65mph limit is a rather magical number in terms of surviving a worst-case scenario. Going above that, fatalities go up dramatically. Going below that... fatalities are significantly lower.
it would also imply that a collision with someone where both of you are going 32.5 miles per hour and hit each other head on would end in near 100% fatality.
That said, I would believe that a head-on collision at around those speeds has a high chance of fatality being that it's a 130mph collision.
They crashed a 100mph car into a wall, a 50mph car into a wall, and then two 50mph cars into each other.
I suggest watching the videos to visually see the proof. The 50mph vs wall is similar to two 50mph cars crashing into each other.
32mph vs 32mph car would have a very low chance of fatality, although the two cars would probably be totaled. When I say ~65mph as a problem, that is the 65mph vs 65mph cars hitting each other head on... or 65mph vs a tree / wall / bridge (which has an equivalent chance of death)
Remember, the kinetic energy of you and your car goes up with the square of your speed.
You made me think for a few more moments on the issue.
The reason 2 cars hitting each other is similar is more due to their mutual crumple zones, so they're helping each other slow down at the same time.
I suspect this would also be dependent upon the car, since newer cars have better crumple zones to help survive accidents better. There's a lot of details that go into actual damage. Most people, when they're in an accident, don't go headlong into a wall. They hit a pothole and spin out, or nudge another car and go spinning, or hit a side wall at an angle, where their speed toward the wall isn't actually 65 mph, and so on.
At the end of the day, it's not that 65mph is the near-death number, as far as car speed is concerned, it's more, as everyone else has been saying, the delta-v. The easiest way to hit 65mph in that way is hitting a tree head-on, or wall head-on. On the freeways, this isn't likely the case, and even the edges of roads where two roads split and there's a barricade are protected by several crunch zones in the road itself.
Edit: ah, I didn't notice that you had been saying delta-v as well. Either way, I still think I follow what you're saying now
I think he's talking about 65mph delta-V, referring to the change in velocity at the (nearly instantaneous) time of collision. Two cars rubbing like that won't produce a 65mph delta-V in the way that a brick wall will. It might be 5-10 mph, which will be enough to shock people but not fatal. He's right that 65 mph delta-V is almost uniformly fatal.
Likewise, if you jump out of a moving vehicle at 65mph, you'll get banged up badly but might not die, because you don't lose 65mph of speed the first time you hit the ground, since you're hitting it obliquely. On the other hand, if you jump from enough height to reach 65mph and hit the ground directly, you're almost certainly dead.
I think it goes without saying that if you are in a crash at 100 mph, you don't live. If it's a brick-wall type crash, you probably don't live at 50 mph.
I'm not saying that there's any good reason to go 100+ mph. In general, I think it's a terrible idea. I'm saying that it's not as bad in terms of bulk risk-to-life as 40 mph in a residential zone.
>> Most highways are underposted and should be 70-90.
Maybe in the middle of Montana or Texas where it's 50 miles between towns, but not anywhere with off/onramps. People are very bad at merging and it'd be very difficult for many vehicles, especially trucks to get up to speed if 90 was the limit.
That's what on-ramps are for. If traffic is congested enough to demand merging (rather than just making sure the road is clear), you shouldn't be driving at 90mph. On the other hand, you probably shouldn't be driving at 60 either. Speed limits should be limits, not averages, or worst-case.
You make a good point when it comes to merging. Speeds of 90-120 mph are reasonably safe on German autobahns, because people have a regimented driving style (absolutely no passing on right, but the left lane really is the fast lane) and follow it to a T. Most Americans aren't trained to drive those speeds, though, nor do they follow lane discipline.
If I weigh 200 pounds am I more likely to be fatally injured in a car crash than if I way 150?
A car that weighs more is safer because its velocity changes are slower (barring collision with an immovable object) and because it will usually have better crumple zones that absorb more energy before turning the passenger compartment into a compactor.
If higher kinetic energy or momentum caused higher lethality, heavier people would die more often and/or heavier cars would be more lethal (for its own occupants) in wrecks at the same speed.
Since it's not always possible to know what speed a car was going when it crashed, and since I haven't found any tables or graphs of either speed or KE [or momentum for that matter] vs lethality, I doubt there's enough data to draw any conclusions about KE being better at predicting lethality. I don't understand what the focus on collision energy is for.
Crumple zones can be independent of weight.
A lighter car is more able to stop (less energy for brakes to dissipate) or avoid a crash (can sustain higher cornering forces, tires being the same).
45 vs. 25 mph in residential zone: child runs out in front of you, hit the brakes but you can't stop in time, hit him still going 30mph and kill him... vs. you stop and don't hit him.
100 vs. 65 mph on freeway: you certainly die vs. you probably die, depending on the accident. Freeway accidents are very bad at either speed. Luckily, there shouldn't be any pedestrians, children running into the street, or bicyclists.
The danger of freeway speed has more to do with differentials. Accident risk goes up 2x every 15-20mph of raw speed but 2x every 3 mph of speed differential (in either direction). If you're in traffic and driving 100 mph, you're probably an asshole because most people won't be, but it's the speed variance (and weaving, tailgating, and other asshole behaviors) that makes it dangerous.
Don't know if it's just me, but for the three months that I lived in NYC, I did not see a single speed trap or cop that batted an eye at speeders (and there are many who drive way too fast).
None of those will exceed 20mph - public transportation and biking (presumably) follow the speed limit and the average human running speed is 5 to 8 mph. Unless it's a subway or a train.
In a city center, your average speed will be substantially less than 20mph anyway no matter how fast you drive (unless you violate laws, running through lights and speeding) due to congestion, traffic lights, etc. A 20mph isn't going to make much of a change to average travel speeds.
Most likely, however, you're not going to be driving 20 miles in a city center. If you're driving more than 10 miles, you'll probably want to use a highway, and the US highway system is extensive enough that you can.
As for biking, I have less of a problem with people biking over 20mph in the city. (However, you're correct that, in practice, there's no way someone's going to average 20mph for a city bike commute. Most people aren't in good enough shape to sustain 20mph on the flat.) I regularly hit 30-35mph on downhills (say, Central Park at the north end) because I know what I and the bike can handle. Bikes are small and agile (it's easy to swerve and avoid hitting someone) and much less massive than a car.
This is about human lives. Once you eliminate birth-defects, car accidents are the leading cause of death for people under 35. Particularly for young kids, who obviously aren't driving.
Car accidents kill 34,000 Americans per-year. That's like if 9/11 happened once a month every year.
And speed matters. Stopping distance and kinetic energy go up with the square of velocity. A pedestrian hit by a car going 20 mph will almost certainly live. A person hit by a car going 40 mph will almost certainly die.