What is the thought process behind having truck speed limits that are 10 mph under the regular speed limit? It just seems to create hazards when trucks try to pass, etc. Is there a good reason for this?

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What is the thought process behind having truck speed limits that are 10 mph under the regular speed limit? It just seems to create hazards when trucks try to pass, etc. Is there a good reason for this?

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I’ve seen this too, and at first it didn’t make sense. But when you factor in the fact that semi trucks have a much harder time braking in an emergency, I think it makes sense.

Not only are they so much heavier than your car, but they also risk jackknifing if their trailer doesn’t slow down as quickly as the tractor does. It’s sort of like the reason that trains take over a mile to come to a full stop. They have a lot of weight pushing their momentum forward, and it’s much harder to stop than a typical sedan.

The rule doesn’t apply to trains because they run on a defined track, and it’s very rare for an obstacle to come into their path. But for a semi truck on the highway, all sorts of things could cause a situation where they need to brake hard. People driving poorly and merging without warning, sudden accidents, poorly marked roadwork, etc.

Trucks weigh a lot more than other cars. That means they take way longer to stop if they need to. By having a slower speed limit for them, it makes it less dangerous by giving them more reaction time

It has nothing to do with stopping distances or weight. It has to do with tires. Commercial trucks are speed limited because of tire technology. Heavy weights carried at high speeds do bad things to tires.

I agree with everything said about the weight of trucks
But could there also be a reason regarding the fact that, if trucks go slower than cars, they rarely have to pass them on normal roads, which removes a potential risk?