WTF is with separate Truck speed limits?

[MinisterofDOOM]

Who came up with this? Can ANYONE explain to me what the supposed benefits are?

In Utah, interestate speed limits outside cities are 75-80mph. For EVERYONE. Cross into Idaho, though, and suddenly trucks (semis--or anything with 5 or more axles) are stuck at 65 while everyone else gets to do 75. On two-lane highways, this is a NIGHTMARE. It should not be permitted. It means lots of passing, even if you're not speeding. Late at night, there are times where you'll get 5 or 6 or more trucks all clustered together and one or two tries to pass, and you'll have the whole damn road plugged up fifteen minutes while they creep past their cohorts at a snail's pace. They have no choice, though: either build up a ten mile long train of trucks, or block traffic and pass.

I don't understand what the possible benefits could be. I don't even understand what some moron might have THOUGHT the benefits would be. It's the interstate. There's no need to stop abruptly. Poorer stopping performance is a non-issue. And these trucks' fuel economy is so miniscule already that the 10mph difference would have a negligible impact (and it's possible that with their high-torque diesels and plentiful gears, there would be no difference AT ALL)--and this at the cost of delivery times, etc. Semis generally tend to have better illumination than passenger cars, so visibility is not the issue. And I15 through Idaho is not exactly windy, so it's not an issue of maneuverability. It's not a weather- or road-condition-based thing; the passes through Malad and Pocatello get nasty in the snow, but these speed limits are in place even in the middle of July. I just can't fathom the origin of the idea, let alone the appeal that caused it to be put into practice.

If I were a trucker, I'd avoid Idaho like the plague. 65mph is a stupid enough speed limit already (don't even get me started on 55mph limits). But when applied to long, straight stretches of high-visibility interstate, it's just asinine. It shouldn't be permitted AT ALL (remember these are federal highways). But particularly, it should not be permitted on any road with fewer than 3 lanes. It's such a PITA.

Anyone have any insight into this weird idea?

[snwbrdr435]

I love your rants

[AZ89two4Tsx]

Lets say the truck drivers only observe the posted speed limits for cars...

Are they being ticketed?

[MinisterofDOOM]

Lets say the truck drivers only observe the posted speed limits for cars...

Are they being ticketed?

I dunno. But modern trucks are equipped with GPS and all sorts of stuff to be tracked by the operating company. I assume that Highway Patrol enforcement is not the primary thing keeping them within limits. I've never seen a truck stopped with reds-and-blues, but then I've got about 5000 highway miles in Idaho in the last three months and I've only ever seen ONE cop. Truckers still travel at 65.

[Jesda]

I dont know much about the trucking business but I certainly despise the way they pass each other. It's like waiting for ketchup to fall out of the bottle.

I love your rants

Me too.

[bigbadberry3]

My guess is something to do with the work load of the truckers and hours per day or miles per day they can travel safely?

[Dattebayo]

Obviously because it takes more force to stop a faster truck in an emergency situation. Reaction times being equal, the truck will stop faster and/or cause less damage traveling 10MPH less. Also, on any sort of incline, you can have brake system fade/failure and get a runaway truck scenario.

Maybe you didn't realize that truck accidents happen as much as they actually do...

[MinisterofDOOM]

Obviously because it takes more force to stop a faster truck in an emergency situation. Reaction times being equal, the truck will stop faster and/or cause less damage traveling 10MPH less. Also, on any sort of incline, you can have brake system fade/failure and get a runaway truck scenario.

Maybe you didn't realize that truck accidents happen as much as they actually do...

This is true. But we're not talking about city driving. This is the middle of effing nowhere. You can see for miles, there's no congestion... The likelihood of needing to make an emergency stop without warning is miniscule.

And, if this were a legitimate concern, why haven't more states adopted separate speed limits?

And then there's the argument that the speed difference and necessity to pass frequently creates just as many new opportunities for accidents as the reduced stopping times prevent.

I imagine you're right, and some farmer who never travels more than 25 miles per hour in his F250 decided this was best for everyone. But he's an idiot, and the separate speed limit needs to go.

[bigbadberry3]

Obviously because it takes more force to stop a faster truck in an emergency situation. Reaction times being equal, the truck will stop faster and/or cause less damage traveling 10MPH less. Also, on any sort of incline, you can have brake system fade/failure and get a runaway truck scenario.

Maybe you didn't realize that truck accidents happen as much as they actually do...

Trucks do have more kinetic energy at the same speed as a car but surprisingly, their braking distance is the same (ideally).

[Bubba1]

Who came up with this? Can ANYONE explain to me what the supposed benefits are?

In Utah, interestate speed limits outside cities are 75-80mph. For EVERYONE. Cross into Idaho, though, and suddenly trucks (semis--or anything with 5 or more axles) are stuck at 65 while everyone else gets to do 75. On two-lane highways, this is a NIGHTMARE. It should not be permitted. It means lots of passing, even if you're not speeding. Late at night, there are times where you'll get 5 or 6 or more trucks all clustered together and one or two tries to pass, and you'll have the whole damn road plugged up fifteen minutes while they creep past their cohorts at a snail's pace. They have no choice, though: either build up a ten mile long train of trucks, or block traffic and pass.

I don't understand what the possible benefits could be. I don't even understand what some moron might have THOUGHT the benefits would be. It's the interstate. There's no need to stop abruptly. Poorer stopping performance is a non-issue. And these trucks' fuel economy is so miniscule already that the 10mph difference would have a negligible impact (and it's possible that with their high-torque diesels and plentiful gears, there would be no difference AT ALL)--and this at the cost of delivery times, etc. Semis generally tend to have better illumination than passenger cars, so visibility is not the issue. And I15 through Idaho is not exactly windy, so it's not an issue of maneuverability. It's not a weather- or road-condition-based thing; the passes through Malad and Pocatello get nasty in the snow, but these speed limits are in place even in the middle of July. I just can't fathom the origin of the idea, let alone the appeal that caused it to be put into practice.

If I were a trucker, I'd avoid Idaho like the plague. 65mph is a stupid enough speed limit already (don't even get me started on 55mph limits). But when applied to long, straight stretches of high-visibility interstate, it's just asinine. It shouldn't be permitted AT ALL (remember these are federal highways). But particularly, it should not be permitted on any road with fewer than 3 lanes. It's such a PITA.

Anyone have any insight into this weird idea?

I enjoyed your rant. You covered some the reasons, but you downplayed their significance in the eyes of the lawmakers/insurance carriers. It's a combination of many factors including the gas mileage (yes it's a small saving for one vehicle, but if you multiply the savings by every truck on the road, it adds up, shorter braking distances, antiquated engineering standards for max speeds in turns by tall vehicles, better crosswind controlability, and politics, of course. With the braking, it's not as much for panic stop lengths as for making safer accident avoidance manuevers from idiotic 4 wheel vehicle drivers who continoually cut semi trailer rigs off.

[MinisterofDOOM]

I didn't think of crosswind susceptibility. There are some areas with pretty nasty crosswinds along I15 in Idaho. That's probably the best reason I've heard for it so far.

[Dattebayo]

There's nothing more complicated than perception. That being said, have you ever driven an 18 wheeler? You may change your opinion on *some* of those things you said if you did...

their braking distance is the same (ideally).

This is why I mentioned the fade or failure situation. While pneumatic brakes are more reliable than hydraulic, they cost a lot more to maintain. Hopefully the operator isn't cheap.

[ADDirishboy]

And then there's the argument that the speed difference and necessity to pass frequently creates just as many new opportunities for accidents as the reduced stopping times prevent.

This has always been my main argument against the separate speeds. Yes, a truck travelling at 75 is going to do more damage than one travelling at 65. But all that extra passing creates that many more opportunities for something bad to happen. There are pro's and con's to both sides, but like you stated earlier, if it's that big of a concern why haven't more states implemented a separate speed limit?