Speed limiters on all trucks and buses?

[lappir]

What's the take her on this thing about putting speed limiters on all trucks and busses to not allow more than 60 to 65 MPH? I am not for it at all and don't understand their logic. Another attempt to blame something else for the attention deficit disorder that plagues the human element. It's not the speed that we travel that causes the accident. It's the ability to remain continuously aware of your surroundings that keeps you away from most accidents. Any distraction while driving can cause an accident, but we won't limit them. What's the common answer when someone asks an accident victim what happened. ' I don't know where it came from, I didn't see it'.

 

Remove distractions from yourself while driving.

 

Rod

[dan412]

I think that all vehicles should travel at the same speed limit. People trying to pass a truck going slower than them causes a lot of accidents.

[Pat & Pete]

We drive within a couple miles of 55 on the freeways and less on lesser roads .

 

No one seems to pay attention to speed limits . How can they be expected to pay attention to something as trivial as a distraction of any sort ? I mean other than their cell phones , GPSs and any array of other supposed necessities . What a joke ...

[Ronbo]

Hard to have everyone drive the same speed. In a military convoy you put the slowest vehicle in the front. I don't want to drive 35 mph just because an elderly driver is in front.

[Pat & Pete]

Then just take a different road .

 

That's what we elderly drivers do .

[noteven]

I believe heavy trucks are speed limited at 105km/hr in Ontario ... not sure how it works there ... I drove there a bit last spring between Toronto and Hamilton and didn't seem to notice...

 

Lots of companies speed limit their heavy vehicles...

 

I don't quite understand the thought process when a truck race takes place on a 4 lane road - one driver pulls out to pass another at 1 mph speed difference... and then the gutless 450hp can't pull the grade with 2.91 gears and he can't make the pass.... exactly how much time are we making up here?

 

Same with knuckeheads who pass on cruise control with light vehicles...

 

Or drive in the left lanes slower than right lane traffic

 

Whhooops OW! ... fell off my soapbox!

[Mark and Dale Bruss]

Some fleets have their trucks speed limited. Many raised the limit after they found that too low of a limit often put the driver in a bind.

 

In a perfect world, everyone driving at the same speed would mean it would be harder, to have accidents. It is interesting that on a 65 mph highway, a vehicle going 80 (15) over is a maniac and yet 50 (15 under) is a safer driver.

 

As for the 1 mph race, that usually happens when a pass is not completed and a hill comes along. Those trucks do not have the horsepower to maintain a high speed climb up a hill. So the passing truck should back off and let the cars by but the space behind the two trucks are full of cars and no place for the truck to back off. Also backing off costs the truck a lot of inertial energy, so the driver continues to pass.

 

Why should cars have the right to pass each other and not the trucks?

 

As to the proposal by the FDOT, it is based on some very sketchy data and is more of a power play than anything important. But who should care, it only affects trucks. And when the cost of trucking rises because of the regulations and correspondingly the cost of delivered goods, no one will complain about FDOT rules.

[Nuke-E]

I think that all vehicles should travel at the same speed limit. People trying to pass a truck going slower than them causes a lot of accidents.

 

Unless you mandate minimum hp/weight ratios, and require foot-on-the-floor driving, it'll never happen outside of plains states when the wind isn't blowing. Most heavy vehicles don't have the power to maintain speed under all conditions, and regardless of a speed limit or speed limiters, you'll have differences in travel speeds. When you have arbitrary limits in place that don't reflect reasonable judgement and sound engineering, you end up with distractions--be it the cell phone or simply a wandering or fatigued mind. As a young driver, in a state where the penalty for 80 in a 70 zone included license suspension, my driving was much more aggressive--if someone held me up even a little, there was no reasonable way to make up the lost time. And while we'd all love to travel in a mode where time doesn't matter, it does--whether to beat darkness, a storm, or to get to a destination/event on time. As I've gotten older and care less about complying arbitrary laws that have no correlation with safety (some of the time anyways), I'm much more relaxed when someone is in the way, knowing I can pick up the pace when the road is more open.

 

We drive within a couple miles of 55 on the freeways and less on lesser roads .

 

No one seems to pay attention to speed limits . How can they be expected to pay attention to something as trivial as a distraction of any sort ? I mean other than their cell phones , GPSs and any array of other supposed necessities . What a joke ...

 

That's been studied for a long time--people generally drive what they feel comfortable with under any particular set of circumstances. Speed limits (and I'm referring to a large body of studies on the subject here) have almost no impact on travel speeds, especially on the open road. In the absence of speed limits, or when they're above where most people feel comfortable, attitudes change--someone comfortable with 75 in an 85 zone doesn't take as much offense to a driver at 65, and neither tends to sit in the passing lane longer than necessary. Montana's experiment with reasonable and prudent and then no general speed law (i.e. no need to be reasonable or prudent for an 8-month period) showed (as noted by the highway patrol) that lane discipline and driver courtesy was much improved. It also stands as the safest 8-month period on Montana's highways.

 

Australia's Stewart Highway also serves as an interesting case study--it had no speed limit prior to 2007, an 81 mph speed limit through a trial suspension in 2013/2014, and now no speed limit after the trial was expanded and extended indefinitely. During the first year with speed limits, fatalities increased 70 percent. Note that the transport minister had argued that no accidents had been attributable to high speed since 2001 in the push to remove the speed limit again on a trial basis. Only two months into the trial, officials were sufficiently convinced to expand and make the change permanent. Fatalites are consistent with the pre-limit period, and lower than when a limit was in place.

 

Hard to have everyone drive the same speed. In a military convoy you put the slowest vehicle in the front. I don't want to drive 35 mph just because an elderly driver is in front.

 

Exactly. And what does everyone do in a convoy? Crowd the driver in front of them, and change lanes at every opportunity to move up a spot. A recipe for disaster.

 

I believe heavy trucks are speed limited at 105km/hr in Ontario ... not sure how it works there ... I drove there a bit last spring between Toronto and Hamilton and didn't seem to notice...

 

Lots of companies speed limit their heavy vehicles...

 

I don't quite understand the thought process when a truck race takes place on a 4 lane road - one driver pulls out to pass another at 1 mph speed difference... and then the gutless 450hp can't pull the grade with 2.91 gears and he can't make the pass.... exactly how much time are we making up here?

 

Same with knuckeheads who pass on cruise control with light vehicles...

 

Or drive in the left lanes slower than right lane traffic

 

Whhooops OW! ... fell off my soapbox!

 

Many states over the last decade have done away with split speed limits for trucks specifically for safety reasons (usually at the hands of engineers disconnected from the ticketing revenue stream). Texas and Ohio come to mind--I used to hate driving I-71 between Cincinnati and Columbus, as it was always an exercise in frustration: cars would sit in the left lane, not wanting to slow to truck speeds nor get out of the way, and when trucks did pass it often took forever, with a logjam of frustrated drivers jockeying to break free. Ticketing for speeding has dropped on all interstates with increased speed limits, by double-digit percentages, with the exception of a section of I-77. Fatal crashes also dropped by more than 10% during the same period.

 

As far as the passes that take forever, I see no surprise. If you're speed limited, and have limited hours behind the wheel, dropping below your maximum speed as a truck driver has a direct cost associated with it. How many people would slow down to let someone by if there was, in essence, a fee charged for doing so? We're legislating the rudeness... It's a matter of time, especially with electronic logging, before you see increased speeding in trucks through small towns and cities, with an associated increase in accidents.

 

Some fleets have their trucks speed limited. Many raised the limit after they found that too low of a limit often put the driver in a bind.

Are there that many that have done that? I'd like to think so, but it would seem that most are concerned more about fuel costs than safety.

By the way--I'm breaking my responses to your post up, as you've got several good points. ;-)

 

In a perfect world, everyone driving at the same speed would mean it would be harder, to have accidents. It is interesting that on a 65 mph highway, a vehicle going 80 (15) over is a maniac and yet 50 (15 under) is a safer driver.

 

That was the conventional thinking for a long time, but it never really played out. There are too many other factors in play--the era of the 55 and 65mph national maximum speed limits never delivered on promised safety, and at a time when speed limits are at their highest (in modern times), fatality rates are at their lowest. In the last few years, the absolute number of fatalities even dipped below the lowest ever recorded post-war several times.

 

As for the 1 mph race, that usually happens when a pass is not completed and a hill comes along. Those trucks do not have the horsepower to maintain a high speed climb up a hill. So the passing truck should back off and let the cars by but the space behind the two trucks are full of cars and no place for the truck to back off. Also backing off costs the truck a lot of inertial energy, so the driver continues to pass.

More than energy, it's miles that they don't get paid for before they run out of hours. Without the speed limiters, they could simply make up the lost time (while still keeping to an average speed that makes sense economically).

 

Why should cars have the right to pass each other and not the trucks?

 

They shouldn't! The same rules should apply to everyone--pass, and move over! Just because you don't have 6 wheels, 3 axles, a trailer, or whatever, you shouldn't be allowed to camp out in the left lane. And if you have the ability to complete a pass without interrupting the flow of traffic, go for it regardless of the vehicle size. In my experience, particularly in big cities (e.g. Atlanta) many truckers have the same attitude. As long as they keep things moving, no harm done. The problem with a lot of those arbitrary lane restrictions is that they devalue some rather important ones--like on I-40 east of the NC/TN line, where the left lane is a couple of feet narrower.

 

As to the proposal by the FDOT, it is based on some very sketchy data and is more of a power play than anything important. But who should care, it only affects trucks. And when the cost of trucking rises because of the regulations and correspondingly the cost of delivered goods, no one will complain about FDOT rules.

I would argue that the only real data that would support the argument that limiters would have a benefit is the high-school level analysis that kinetic energy increases with velocity. The empirical evidence is overwhelmingly making the case the other way. You have to look at the big picture of what's taking place--without getting too political, it's an example of crony capitalism. All you have to do to see this is see ATA lobbying for the requirement, and OOIDA staunchly against it. The big fleets are lobbying heavily to require regulations that are difficult for the owner operator to deal with--things like a specially-certified doctor for physicals, electronic logging and data recorders, speed limiters, etc. The big fleets will leverage their size to do things like having a doctor in-house, purchase the logging equipment in bulk, and set speed limiters in-house instead of paying dealer rates. The speed limiters also make it harder for an OO to match (or beat) fleet schedules in terms of time. If the fleets think something benefits safety, it should be in their own financial interest to adopt the technology, and they should be able to show that they're safer than the independent driver.

 

Which make me curious now if I can extract the data for fleet vs. independent driver fatal accident rates from the federal database....

 

I've been working on a journal article with some UT professors that calls into question a lot of the speed mentality based on a fundamental question I asked a few years ago, and a simulation to test it out. We've always historically looked at fatality rates on a per-mile basis. It has value, as it accounts for economic (and other) drivers that change the amount of driving year to year--it's a good macroscopic indicator. But at a microscopic (i.e. individual driver) level, it's actually not very representative in suggesting how we should drive. There are basically two types of accidents--those that result from you making an error of some kind, and those that result from something external (another driver, animal, debris, etc). The first type is likely to increase in probability as you drive faster, but the latter is something of a random event in the time domain (and acts just like a neutron transport problem...). I usually try to explain it in terms of nuclear physics (woohoo! big words!), but it basically boils down to the idea that the deer will cross the road at some point in space and time, and you have to be at that place at that time for a collision to occur. Basically what that boils down to is that your odds of colliding with a deer are proportional to the time you're on the road. Things like stopping distances generally wash out, because while they get longer with speed, your time on the road decreases. Reaction time is fixed in time (provided your headlights aren't limiting, which they aren't if you've been around me long enough!), so it doesn't affect the probability.

 

So, how does all of that rambling result in a simulation? Well, for all rural interstate fatal crashes, it's possible to isolate vehicles that caused an accident from ones that got hit. You can also separate the other events--like hitting pedestrians (about 5,000 killed a year, but not many on rural interstates), animals, debris, and vehicle problems. Vehicles that caused accidents are assumed to have an increasing frequency with speed (the degree to which that happens can be varied--linear, quadratic, or cubic), but doesn't change the result too much), while the rest follow the same time and place collision probabilities. Run the simulation varying the speed of a vehicle with the real data on fatal accidents, and you definitely get a speed where your likelihood of a collision is minimized. But that speed is slightly in excess of the highest legal speed limit in the US, at about 110 mph. It sounds crazy, but 110 mph for a modern passenger car is plenty controllable (see the autobahn, autostrada, and the Australian outback's speed un-restricted highways with lower fatality rates than our rural interstates) in good weather and without congestion. On the whole, if everyone gets to their destination in less time, the vehicular density on the roads goes down, meaning that while you might be more likely to screw up, you're less likely to take someone else with you. You're also more likely to arrive before being fatigued, and are more likely to be able to put off the text message and sit down for dinner when you get there.

 

Before anyone gets too spun up, don't think I cruise around with all 14 wheels spun up to 110 mph. Part of the benefit of cutting off the ball and chain is letting the more capable vehicles get gone and out of the way, and making my cruising in the big rig more relaxed at 65-70 mph on the open road. It's in the government's interest to enforce speed restrictions--just the District of Columbia, speed cameras have raised over a quarter-billion dollars. Even mid-size cities like Knoxville rake in tens of millions from speeding tickets annually. Most have learned from the Arizona photo-ticketing experiment that to maximize revenue, you have to keep the penalties to a level where it's not economical to fight, even if the ticket was issued in error (and especially with photo ticketing, that's a high rate--Maryland has been caught issuing tickets to school buses for speeding while kids were getting on!). In North Carolina, once a court ruling made clear that the state constitution required gross revenue go to public schools, the photo enforcement programs were all shut down. If it was about safety, there would have been a justification to keep them going.

 

Continuing on the enforcement subject and what the revenue from speed and red light enforcement can do to/for local governments, the Chicago transportation official responsible for the camera contract there was sentenced to 10 years in prison for the $2 million in bribes he took from the camera company. Their lobbyist donned a jumpsuit last week, with a line of officials at Redflex waiting in line. And that's just for Chicago--investigators have already shown that bribes took place in at least 12 states, and includes the police chief in Oak Ridge, TN.

 

I think my soap box is collapsing under the weight of this post, so I'm going to quit now...

[Bob Cochran]

Wow excellent answer love it. I will only add because I feel the need tonight. I think Nevada still has the safe and prudent speed out in the waste lands. Only problem is you and LEO may not agree on what that speed is!!!

[Nuke-E]

Wow excellent answer love it. I will only add because I feel the need tonight. I think Nevada still has the safe and prudent speed out in the waste lands. Only problem is you and LEO may not agree on what that speed is!!!

 

Like most states, Nevada has a basic speed rule that requires that you not drive at a speed greater than what is reasonable and prudent, independent of other restrictions. The maximum speed limit is 80 mph though, which applies statewide unless otherwise posted. The last part is what left Montana without a basic speed law--its state supreme court ruled in favor of a challenge to "reasonable and prudent" on the argument that it was unconstitutionally vague. If I remember right, the guy was driving a Camaro, and was cited for about 80 mph. The state moved to implement a 75 mph speed limit, which was consistent with surrounding states at the time, but it's now 80 there as well, and joins Nevada along with Utah, Idaho, South Dakota, Wyoming, and Texas (not counting the 85 mph toll road operating through bankruptcy). Interestingly, while national fatality rates were up slightly in 2015, South Dakota saw a decline after raising speed limits to 80 at the start of April.

 

I keep meaning to put together a plot showing speed limits changing over the last decade along with traffic fatalities. While there are lots of relatively new distractions out there, we're finally reaching a point where most cars on the road have passive restraints (e.g. airbags), and seat belt use is relatively common. I did dig up my presentation on this subject from a couple of years ago--of the 34,009 vehicles involved in fatal crashes where one of the drivers goofed up, only 6,164 of the drivers were sober. Same thing with pedestrian deaths--of 5251 deaths, only 2 were as a result of sober drivers. (2012 stats) My model predicted the actual number of vehicles involved at 50 mph, just a tad higher than the actual average of 46 mph. And changing reaction times in the model only varied the optimal speed within a 20-mph window, suggesting that distractions wouldn't account for a significant change in the number of fatal accidents. Among the more than 30,000 people killed each year in car crashes, only about 100 are attributable to the little handheld phones/computers we all have--including the stuff like texting that would seem to be incredibly dangerous on its face.

[Mark and Dale Bruss]

Sometimes things are related to other things without a true relationship. Back in 1973 when the 55 speed limit limit was forced upon the US because of the fuel crisis, there was an apparent reduction in traffic fatalities. My wife at the time worked for the Wisconsin DOT and in talking about the reduction in speed caused a reduction in fatalities, she pointed out that the State statistics showed the real cause of the fatality reduction was people were driving less. The real number is not the number of fatalities but the number of fatalities per 100,000 miles driven. This is a number that has been dropping ever since the 55 limit was stopped.

 

Likewise, when the 55 limit was introduced as a fuel saving measure, in Wisconsin the trucking industry fought the new speeds with scientists and engineers who proved that dropping the semi speed from 65 to 55 did reduced frontal air friction but dropped the truck into the rolling friction zone and dropped the fuel mileage. They lost.

 

At that time I was driving daily from Milwaukee to Madison, about 90 miles. I was driving a V-8 Chevy pickup with a 30" flat sided cap, not exactly an air-streamed profile. I ran pretty close to the speed limits and my mileage dropped when I slowed to 55.

 

Fuel economy was not benefit of the 55 limit. I always felt that at the time, 55 was the maximum speed any of the electric car prototypes were capable of and this was a way to promote electric cars.

[rickeieio]

Well stated David.

 

It's been my (unscientific) observation that speed doesn't kill, it's the difference in speed that causes issues. We recently drove from Indiana to Colorado and back. I noticed that in states with higher speed limits, there was far less lane changing and fewer folks camping in the left lane. As a result, even though I was driving well below the posted speed limit in some states, we made better time overall.

[noteven]

Last trip through Utah on I15 with 80 mph speed limit we noticed hardly anyone was speeding.

[Mark and Dale Bruss]

The transportation people look at a highway like a pipe. Bernoulli's Principle can be applied in that as the flow of a fluid through a pipe increases, the pressure decreases. The traffic engineers look at a certain volume of vehicles will be on the highway for a given time. The slower the traffic the pressure will increase (the vehicles will be closer together). If the traffic speed is increased, the pressure is reduced (vehicles farther apart).

 

Think about the times where construction cuts off one lane and then the state reduces the speed also. Since a vehicle uses only one lane, the speed factor for a lane should be no different whether there are adjacent lanes or not. Certain considerations for construction vehicles entering/exiting the construction area but e have gone through miles of single lane reduced speed highways this year. Except Montana which closes lanes but doesn't change the speed.

 

​Another interesting phenomena is the states that have different speed limits for truck than cars. Those state are force more differential flow which does lead to more accidents. Another case where "common logic" fails.

 

​Another phenomena traffic engineers observe, speed limit compliance increases as the limits are nearer to what feels natural for the driver. The concept of "5 over" drops as the limits increase. The problem with the 55 limit was that is never felt natural. At 70, few exceed the limit, at 80 (we were in Montana) many drive under the limit. The State of Maryland finally conceded on the 55 limit, which was the second largest revenue source for the state, when the Feds said they were going to pull the highway maintenance funding for lack of "speed limit compliance." The state raised the limit to 65 and compliance increased. I guess the ticket money wasn't as much as the Federal funding.

[gjhunter01]

Get ready for driverless long haul trucks in our near future running non-stop across country. We work on a sugar beet farm in ND that uses auto steer tractors. A operator sits in the cab to monitor the tractor which drives itself and doesn't miss a beet during harvest. Only a matter of time for the trucks.

Greg

[justRich]

Well stated David.

 

It's been my (unscientific) observation that speed doesn't kill, it's the difference in speed that causes issues. We recently drove from Indiana to Colorado and back. I noticed that in states with higher speed limits, there was far less lane changing and fewer folks camping in the left lane. As a result, even though I was driving well below the posted speed limit in some states, we made better time overall.

Also observed and noted.

FYI: Speed Limiter Case Study and Industry Review from Canada where two provinces have required truck speed limiters for several years.

 

And just for fun:

[Nuke-E]

Sometimes things are related to other things without a true relationship. Back in 1973 when the 55 speed limit limit was forced upon the US because of the fuel crisis, there was an apparent reduction in traffic fatalities. My wife at the time worked for the Wisconsin DOT and in talking about the reduction in speed caused a reduction in fatalities, she pointed out that the State statistics showed the real cause of the fatality reduction was people were driving less. The real number is not the number of fatalities but the number of fatalities per 100,000 miles driven. This is a number that has been dropping ever since the 55 limit was stopped.

 

Likewise, when the 55 limit was introduced as a fuel saving measure, in Wisconsin the trucking industry fought the new speeds with scientists and engineers who proved that dropping the semi speed from 65 to 55 did reduced frontal air friction but dropped the truck into the rolling friction zone and dropped the fuel mileage. They lost.

 

At that time I was driving daily from Milwaukee to Madison, about 90 miles. I was driving a V-8 Chevy pickup with a 30" flat sided cap, not exactly an air-streamed profile. I ran pretty close to the speed limits and my mileage dropped when I slowed to 55.

 

Fuel economy was not benefit of the 55 limit. I always felt that at the time, 55 was the maximum speed any of the electric car prototypes were capable of and this was a way to promote electric cars.

 

The fatality rate is an important metric--and you're right, it definitely didn't drop with the start of the NMSL. If anything, the decline was halted--from 1975 (first full NMSL year) until the early-80s, there was no decline in the fatality rate. The chart here lays it out pretty clearly. Of course, anyone alive at the time (sorry, not speaking from experience here!) knows that everyone didn't suddenly drive 20mph or more slower than previously--free-flowing travels speeds didn't change much, absent heavy-handed enforcement. Many states complied only to the minimum extent necessary to retain federal highway funding, and created special categories of speeding, or "energy wasting" fines that were minimal. Right off the top of my head, I know Nevada and Tennessee both had these, and I'm sure other states that protested the NMSL (like Michigan) did as well.

 

What I'm arguing is wrong about using the just the fatality rate to make safety decisions is that a lot of the random events that occur on the road occur independent of how many miles you drive, but proportional to the amount of time you're on the road. Those two things are interchangeable if your speed is fixed and you vary the distance you travel, but most of us are traveling to reach a destination, not out to spend a day cruising (though I can certainly enjoy that, and know others do too). Whether it's a trip to see grandma, the daily to-and-from the office, school, or grocery store, you generally don't get to change how far you drive for non-pleasure activities. So if the distance is fixed, increasing speed reduces the odds that the meteor, deer, drunk, or distracted driver is in the right place at the right time to hit you.

 

Generally speaking, when distance traveled increases nationwide, the time on the road does too, which in addition to random events affects things like vehicle density.

 

Well stated David.

 

It's been my (unscientific) observation that speed doesn't kill, it's the difference in speed that causes issues. We recently drove from Indiana to Colorado and back. I noticed that in states with higher speed limits, there was far less lane changing and fewer folks camping in the left lane. As a result, even though I was driving well below the posted speed limit in some states, we made better time overall.

 

I think even more so than the difference in speed it's an attitude of complacence--if you're driving at or slightly above the speed limit, you're less likely to care about the reckless maniac driving a little bit faster. If you're below the speed limit, there's some understanding that faster is reasonable, and afford more courtesy. To extend Mark's use of the pipe flow analogy, low speed limits create solid masses in the pipe, with irregular flow and blasts ahead when the clump breaks apart.

 

The smartass in me would point out that speed by itself isn't a problem at all--it's usually really abrupt stops that are the killers. But there are too many pilots on this forum that would see the close relation to the statement that flying is perfectly safe when you don't have any unplanned landings.

 

Also observed and noted.

FYI: Speed Limiter Case Study and Industry Review from Canada where two provinces have required truck speed limiters for several years.

 

And just for fun:

I find that study kind of interesting, and would love to read the whole thing. I would have thought (unless they've got the same special interest problem that we do) that fleets would be able to show the efficacy of implementing speed limiters, either with fuel savings or decreased accident rates. Maybe the real data is to the contrary, and there's an element of saving face in play. Or maybe they don't want other fleets seeing the savings and doing the same thing (though in that case, you wouldn't think they'd be pressing for a law that would do just that).

 

Anecdotally, out on the open road, I know that when I'm behind the wheel I tire more quickly when I'm bored--and not just miles sooner, hours sooner too. I presume it's adrenaline, but quickening the pace makes a big difference, and as an added bonus I get there sooner--what I don't know is how much of that effect goes away when I'm only alert to control the vehicle and watch for actual hazards, instead of also needing to look for flying tire salesmen. Bonus points for getting the reference (in my opinion they're among the better ones out there), but here's a very interesting read on how they like to conduct speed enforcement: http://www.caranddriver.com/features/busted-from-cloud-nine