livedarklions

You completely missed the point--you offered a simplistic unsupported assertion that assumed the rest of the world's lockdowns were more severe than the US (news flash, they weren't uniform), and ended up with a conclusion of little to no interest or application. You then became quite nasty when op tried to get the thread back on topic. In the process of this, you then started making an argument based on false premises that grossly distorted the history of the US. I've yet to see any purpose behind this weird shift other than to ridicule cross-national comparisons.

It's weird that you think having people disagree with your posts is an "attack" and that we are making assumptions about you. As I have said several times, I'm baffled by your vehemence when you have such a complete lack of a point.

livedarklions

The bet is absurd and completely besides the point. First of all, speed and size of car are disproportionately high in the US so that's almost certainly not true, and second, as a cyclist or a pedestrian, why would a person care about such an absurd statistical reframing? If anything, it would just indicate that US drivers do more of their driving on restricted highways.

I think the real disconnect here is that you seem to want to ignore much of what the op article was saying about the nature of motor vehicles in the US vs. Europe and would rather shift the argument to one about the supposed motivations and agendas of other people in the thread.

livedarklions

So can cancer, so I guess that cars don't matter at all.

That's illogical. It's the difference in likelihood of getting killed by the object that's important. If you know anything about kinetic energy (which is what actually kills people), it increases greatly with weight. Also, the size and height of the SUV may affect the driver's ability to see and avoid you, as well as making it more likely that the pedestrian or cyclist will end up under the wheel.

Kontact 

https://www.nejm.org/doi/full/10.1056/NEJMra2025746

FBinNY 

If you're going to argue physics, you have to keep the facts straight. The vehicle's weight (compared to other vehicles) makes much less difference than you imply.

What matters most is it's speed and angle of impact. While there's marginal difference between the effects of being hit by a 6,000# vehicle and one half it's weight, there's a great difference between one moving at 40 vs. 30mph

However, as you point out, shape is critical. The difference in grill/hood height of SUVs and trucks vs. that of typical cars determines whether you'll tend to be lifted allowing the car to slide under you, vs. being driven forward and/or down.

IMO the difference in fleet mix accounts for a large part of the difference in consequences, though it wouldn't factor in the number of crashes.

3alarmer 

...I wonder why they call it the "Raptor" ?

livedarklions

If you double the weight, you double the kinetic energy. I don't think a linear relationship is marginal. Yes, the other effects of size and speed may by themselves have larger effects, but it's the interaction of shape, weight and speed that's making US vehicles especially deadly when compared to the averages for other countries.

I'm not sure if it does factor into the number of crashes, but it does factor into the severity of injury.

FBinNY 

Yes, that's true, but not relevant. It's not the total kinetic energy that matters. It's the transferred energy, or more specifically the acceleration the struck person or object undergoes.

Consider --- Imagine a bicyclist smacks into a brick wall at 40mph and another is stationary when struck by an SUV moving at 40mph. Which would suffer greater injuries? How? Why?

Keep in mind that a stationary wall has no kinetic energy, and an SUV has much more kinetic energy than a bicyclist at the same speed.

Lastly consider 2 vehicles: an 8,000# SUV moving at 20mph, and a 2,000 Mazda Miata doing 40. Both have the same kinetic energy, which do you think would cause greater injuries if it hit you?
Why?

Amitoj

Since kinetic energy and momentum have a direct linear relationship (k.e. = (1/2)m*v*v), a heavier object will transfer more energy to the cyclist than a lighter one, which wont be too kind to our bones, joints and internal organs. This is also the reason why a heavier bat does not need to be swung very fast to dispatch a ball to the boundary in cricket.

livedarklions

Actually, it's your points that are right but irrelevant. The more kinetic energy the vehicle has, the greater the likelihood a fatal transfer will occur.

We're not discussing whether brick walls should be placed in roads, so that comparison is both completely irrelevant and also completely useless. There's too many variables involved to answer that on the individual case and regulation addresses probabilities, not the specifics of individual cases. Your example is the equivalent of asking whether I'd rather jump off of a 100 story building or get hit by a car. Absolutely pointless.

The only relevant comparison is between two cars of different weight hitting the person at the same speed, because what you're missing is that the difference between the impact of a vehicle weighing 8000 pounds and 2000 pounds increases with the speed. In other words, the faster the vehicles, the more the weight differences matter, by a lot. Why am I assuming for this example that the larger vehicle is moving much more slowly? That's not real-world. Are you really claiming that getting hit by an 8000 pound vehicle at 30 mph is not more likely to cause great injury than a 2000 pound car at the same speed? Absurd.

Have fun with this calculator: https://www.calculatorsoup.com/calcu...cs/kinetic.php

I'll take this quibbling seriously the next time I read about a brick wall suddenly materializing in the middle of an intersection. In the meantime, the pedestrian/cyclist struck full on in intersection by light-running driver is too common a scenario to discount.

livedarklions

Right. I think the problem with the intuitive approach here is that people don't have enough experience with getting hit by very heavy objects to grasp this intuitively and if they have, they probably didn't survive it.

I also think it's an artifact of how we look at the regulatory problem. We're used to speed limits, so if you're going to argue for a lower one, you'll probably plug in a number for average vehicle weight just to show how differences in v-squared are huge with just a 10 mph reduction in speed. We probably don't do the calculation for different vehicle weights because we really aren't used to the concept of regulating vehicle size except on bridges and the like. When you multiply that linear weight difference by v-squared, you get dramatically different figures for the effectiveness of that 10 mph reduction in absolute terms.

And we haven't even touched on the obvious implications of increased kinetic energy on braking distances.

FBinNY 

Let's try this again from another direction.

I suspect that the problem is that you are applying HS physics analysis for elastic collisions to what is a very non-elastic situation, and/or overestimating the materiality of weight differences in vehicles that are already over 15x the weight of the rider or pedestrian. Let's start by noting that humans don't bounce very well (or in tech speak, have a rebound ratio near zero) so instead of trying estimate rebound, let's just focus on what happens to the struck object, ie the bike rider.

When struck squarely by a moving vehicle with a flat front the person is accelerated very rapidly to a speed roughly equal to that of the vehicle. (the weight of the striking vehicle does enter into this, but given the ratios of the vehicle of the vehicle to the human, the difference between 15x and 30xor 60x doesn't make enough difference to fret over)

So the issue is the sudden (near instant) acceleration to vehicle speed and the G-forces involved. The time and distance are attenuated slightly by crumpling of the vehicle and body, but at anything over 30mph the G-force is enough to be fatal or at least cause great trauma, regardless of the vehicle weight. Since you can only die once, the effect of the greater vehicle weight matters much less than implied above, though it might be a factor at lower speeds.

If you prefer, you can do the math making sure to apply the formula for non-elastic collisions, but the results won't change.

BTW- because the trauma depends on the G-forces, and not the vehicles kinetic energy as posited, safety engineers correctly focus more on impact speed vs.weight.

So I stand by my original statement in post #80 that vehicle weight matters less than speed, or other factors like shape, angle of impact, and crumple zone.

livedarklions

No, pretty sure you're pointing to a number of factors that interact to create a higher fatality rate and just discounting one. In the meantime, here's a study that shows a fairly direct link between vehicle weight and fatality of collision with pedestrians. Please note that a difference as small as 100 kilograms produces a significantly higher rate of fatality:

https://www.sciencedirect.com/scienc...12012221000241

and another:

https://www.sciencedirect.com/science/article/abs/pii/S0022437522000810

and another:

https://are.berkeley.edu/~mlanderson...auffhammer.pdf

and a lay article:

https://medium.com/sidewalk-talk/the...s-c82a0ee8dc0b

late

FBinNY 

I'm not discounting anything, simply looking at the data with an open mind, and weighing factors that may produce the observed effects.

If you had actually done the calculations, you'd know that while mass is a large factor when strike and stuck are similar, the resulting changes get smaller as the disparities increase.

I'm familiar with various data sets, and less focused on the what than on the why and how that might explain them.

For example, there's been a trend to injuries happening higher on the bodies, and the mortality for children increasing faster than for adults. Those both point to higher front ends being an important factor.

As we look for explanations for changing outcomes, we need to look at changes to inputs, then for a mechanism to move from correlation to causation.

livedarklions

I think it's probably completely pointless to try to convince each other either way as the factors of size, weight and shape are so closely related that trying to sort them out is probably a fools errand. They all point in the same direction anyway. Having masses of people driving around in small trucks/vans/SUVs poses a higher danger to cyclists, pedestrians and other people in cars than having those masses in smaller vehicles.
I suspect these factors are not talked about enough in the safety advocacy context because it's politically difficult to advocate for a car size diet, worse even than for bike infrastructure.

FBinNY 

Agreed that it's pointless here, since what any of us believe hardly matters. But I do disagree with some of your conclusions. Earlier in the thread you disparaged experts for emphasizing speed over weight, saying they did so because it was in their comfort zone.

Now you say there's a resistance to talking about reducing average car weight.

Decades ago there was a major trend to smaller cars over fuel efficiency factors. Then fuel coats dropped (inflation adjusted) and we complacent.

Now, we're in a new bind because the shift to electric cars means cars will get markedly heavier.

But there are things we can do change front end profiles. So, for example, if I were an engineering student I be using computer simulation, and crash testing to see how to make cars safer for those other than their occupants.

In government, I'd be focusing on getting insurance rates to better reflect total damage considerations rather than only to occupants.

In the past, safety design, marketing, and insurance focused mainly on the occupants. That needs to be revisited, because a major reason there's so many heavier cars on the roads is because they're seen as safer (for the owners). It's an area I care about, not only as a cyclist, but as someone who drives a 2,100# low sports car.

3alarmer 

...it took many years of safety advocacy focused on the government to institute the requirements for car makers to include something as intuitively obvious as seat belts and shoulder harnesses in their products. Meanwhile, there were correlation versus causation arguments about how there were people whose lives were saved by being thrown clear of the car in a wreck.

I don't really need an elaborate analysis of these statistics to know that the Raptor pictured in post # 81 is a much more dangerous design to everyone outside of it than it needs to be, for a number of reasons. There is no reason for these SUV and light truck designs that meets the criteria of rational thought, other than an appeal to marketing them via the reptilian portion of the human brain. And it is quite typical of what is being sold, right now in the USA, in very large numbers, bolstered by safety ratings that only consider the occupants. An 8,000 pound GVW electric pickup truck might eventually pencil out to lower emissions, for climate change purposes. But I'm pretty sure the number of people who buy them, as opposed to the number who need their capacity and range, will be wildly unbalanced.

On the original topic, that the fatality numbers here for walkers and cyclists are higher than the rest of the first world, there seems to be little doubt that it's true. Various explanations have been proposed, like "we have more rural drivers, thus less familiarity and expectation of encountering someone on a bicycle". Or your proposal that, given this is just how it is, the biggest practical impacts can be made through teaching pedestrians and cyclists that it really is dangerous out there, and some ways of avoiding the worst. Meanwhile, the only changes I see on the car manufacturing front are bigger, faster, and taller. " You'll be safer in our SUV, because it weighs more, and it's high enough to roll over the pesky impediments you might encounter in your daily driving."

And as we have already agreed, those new SUV's and pickups are going to be on the road for another 20-30 years. And that's just one aspect of the problem. You can die from more than one thing at a time. An example is if one of those ginormous new Pickup trucks hits me on the inadequately spaced bike lane on H street here, because it's too narrow to have 30 mph traffic going in both directions, along with bike lanes on each shoulder, and he wants to squeeze past me, because I'm not riding 30 MPH, and he doesn't want to veer over into the oncoming traffic lane.

Lizard brain says, "Need to go faster, and this guy on a bike should be farther over to the right anyway. This will be a good lesson for him."

I'm not saying the majority of motorists drive this way, but fatality statistics are constructed from the wreckage guys like that leave behind in their wake.

3alarmer 

...yes, I agree with the majority of this. With possibly the exception of the bolded statement.

There is no reason for electric vehicles to get substantially heavier, other than the marketing of them to an American, bigger is better, longer range per charge is important, and you should buy a car to meet the one time in ten years you will need to haul five passengers and a full load of construction materials to your building site, mentality.

The Nissan LEAF was a remarkably forward looking design. The originals had a range of roughly 100 miles per charge, a somewhat lightened body design using a lot of composites (to balance out the heavier battery situated under the floor), and a relatively sporty handling package. Nissan had a great deal of trouble selling them in America. For a few years after the American rollout, most of them ended up as lease cars, later resold as used lease cars. As useful as they are, they simply did not appeal to American sensibilities. IIRC, for several years, Tesla's at approximately twice the price were outselling them.

Daniel4

Interesting.

8-80 safe streets.

The first thing I'd do is relocate the engine from the front to the back. Then make the front end completely collapsible in the event of the current smallest collision victim: children. So a 3000lb vehicle from 50mph colliding into a 30lb victim will have to have the front end absorb all the impact so the victim has to emerge unharmed. If the impact takes 50ft or 100ft to decelerate to a full stop into a brick wall, so be it. The victim will have to survive uninjured.

Whether or not the front end will have to be replaced or resilient doesn't matter as long as repairs will be easy and affordable so it won't cost insurance companies too much money.

FBinNY 

Absolutely agree. Only a small percentage of cars are driven more than 50 miles per day. A thinking person would realize that they come out ahead saving front end cash with a low range car for daily use, and renting when more size or range was required.

I made a similar decision when I shifted to bike commuting. After surrendering my plates and cancelling my car insurance, my annual rental costs were less than the premiums had been.

By the same logic, multi-car families could buy only one "family trip" car and one (or more) low range car for daily runs.

The list of possibilities is endless, but as long as our "leadership" is focused on protecting people from the consequences of their actions, we won't see the kind of intelligent dialog that leafs to changes.

I'm resulting the temptation to head down the big picture rabbit hole, it's just too deep......

JW Fas

Unless we have some major breakthrough in battery technology that is producible on a mass scale, longer range means adding more Li-ion cells and, in turn, more weight. The energy density of lithium ion is about as good as it will get. You CAN make a denser Li-ion matrix, but you'll risk thermal runaway.

3alarmer 

....maybe there is some failure to communicate here ? My point was, essentially, that longer ranges in BEV's is a questionable goal, even though range anxiety is a popular marketing tool. 100 miles per charge is pretty good, IMO, and accomplishes the vast majority of trips for which I use a car. You can buy hydrogen fuel cell cars where I live now, and there's a Shell hydrogen fueling station 5 minutes away from me. I think they are very cool technology, but overkill for my needs, in terms of range and current pricing.

Here's a link to the GVW of the Nissan LEAF, which started out as a well designed, rational alternative in the BEV marketplace at about 100 miles per charge range and a weight of around 3400 pounds. They couldn't compete in sales, and were having trouble selling them, so since 2019 have joined the extended range wars, and now weigh in at 300 pounds more. All of which is battery. Range anxiety is a mindset that is well established in America, and for people who live in urban environments, is kind of senseless.

livedarklions

I never "disparaged" experts for emphasizing speed, I am saying that we have gone too far in the direction of ignoring weight and other relevant vehicle characteristics.

I've also got to say that your history is missing the rise of the SUVs in the 1990s-2000s, which was a bit more than just complacency. There's a too much regulatory and political aspects to that story to go into here.

I suspect we're going to see a trend to smaller vehicles when ev becomes more prevalent as expending so much battery life hauling around the weight of the huge batteries is going to be a pretty bad economic deal.