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It’s not vehicle speed that kills, it’s vehicle *momentum*. A smaller car going faster may deliver less impact than a large vehicle going slower (momentum = velocity * mass).

We already have the (table stakes) technology to apply geo-fence-based speed throttling. And this should definitely take momentum into account. So if someone decides to use a 40% larger-than-average car in cities, their speed limit should be throttled to be 40% lower-than-average. Momentum-based limits!

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@yosh isn't the formula for kinetic energy Ek = 1/2 * mass * velocity² ? So velocity has a lot more influence on the energy than mass...

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@yosh car geometry is important too! Higher and flatter (front) profile should geometrically push down velocity and access restrictions!

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@yosh But on the other hand rules for these would destroy most forms for public (and communal) transport, unless you make special rules for it depending number of passengers. I think it is probably much better to do as places such as Germany and make emission limits for inner cities (though probably more aggressively)
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@yosh Then I think it is much better to regulate for the specific segment of vehicles and their access than to look into momentum based limits. That they are driven by professionals does not make them immune to accidents. I agree that they should not be in the city, but I am not sure that it is a good way to do it. I am not even sure it would be safer because the different speed limits would cause issues with the flow of traffic.

And yeah you are probably right about that the idea I presented above will not really be that efficient.
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Edited 1 year ago
@yosh Yes I agree, we should limit the speed and access of all cars. Optimizing for flow of traffic is not only for the cars, it is also to make the traffic predictable, if it is not it will be more unsafe for everyone. You don't want cars to make blind passings or similar because they are stuck behind a slow car or similar that is already enough of an issue outside of cities.
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@yosh

"So if someone decides to use a 40% larger-than-average car in cities, their speed limit should be throttled to be 40% lower-than-average. Momentum-based limits!"

But that means everyone around them is throttled to 40% lower speed limit. Best just to keep them off the road in the first place.

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