Speed limits

[4x4ord]

The speed limit on the straight desolate paved road that goes past our place is 80 km/hr. The people who use the road drive whatever speed they please and for the most part it works fine ….. until you come across somebody driving 80 km per hour. The other day I was riding my bike through Banff national park and rode at the upper end of how fast traffic was moving …. about 130 km per hour. For the most part people drove 120 - 130 km/hr. Fortunately there wasn’t a sole driving the posted speed of 90 km/hr. How should we view speed limits? Is a speeding ticket simply a driving tax?

[Groover]

I wish someone would explain the problem with differential speed to our lawmakers. I am not a commercial truck driver but I believe that having lower speed limits for them creates more problems than it solves.

Truck differential speeds is one reason that I am looking forward to the Tesla semi. The Tesla semi has enough power to pull the vast majority of hills at whatever speed the cruise control is set on and with regenerative breaking speeding going downhill has no benefit as the energy can be saved by other means.

[valhalla360]

toedtoes wrote:
No, I am saying that the data does not suppoet your hypothesis that slow moving vehicles are the cause of collisions.

The facts are well established. The engineering community pushes the 85% speed because it's safer and the primary reason is it reduces differential speeds. You don't have to believe it but it's true.

[JRscooby]

rhagfo wrote:
Wow, how we digress!
Following distance, I like allowing enough space that I don’t need to be constantly watching the vehicle in front of me. I prefer to be looking a 1/4 mile or more ahead of me, I hate surprises! By looking well down the road I will see slowing, and or braking well ahead of me so I don’t need to be slamming on the brakes.
I see way too many lines of vehicles traveling at 60 to 70 mph less than a car length apart! This is how you get 30 car pileups!

Yes, much better to see the reason the car in front of you will slow down, before he starts to slow. But that does not help for say the deer that can't read the crosswalk sign.
Now once the tailgating gets tight enough that bumpers bump before the driver can hit brakes, it is better that they run real close together. When the first slows, the 2nd will hit while doing near the same speed.

[ssthrd]

spoon059 wrote:

Bumpyroad wrote:
If one kid has an IQ of 100 and another gets in with an IQ of 100 the combined IQ would total out to about 60.
bumpy

None of us are as dumb as all of us...

Well said, bumpy. Funny things happen when a couple of youngins get together in a car.

[rhagfo]

Wow, how we digress!
Following distance, I like allowing enough space that I don’t need to be constantly watching the vehicle in front of me. I prefer to be looking a 1/4 mile or more ahead of me, I hate surprises! By looking well down the road I will see slowing, and or braking well ahead of me so I don’t need to be slamming on the brakes.
I see way too many lines of vehicles traveling at 60 to 70 mph less than a car length apart! This is how you get 30 car pileups!

[toedtoes]

Bumpyroad wrote:

Thunderbolt wrote:

I have to agree. this discussion is silly, bordering on stupid.
bumpy

Since when is a discussion on safe following distance silly ? There are many silly things discussed on this forum, but safety isn't one of them. Just because people have a differing opinion on what is safe makes it silly ?

I was referring to the quibbling about 3 or 4 seconds, of F-150 PU or VW bug, that debate was silly bordering on stupid.
bumpy

Actually what is silly is thinking everyone can easily judge distances while in a moving vehicle.

[Bumpyroad]

Thunderbolt wrote:

I have to agree. this discussion is silly, bordering on stupid.
bumpy
Since when is a discussion on safe following distance silly ? There are many silly things discussed on this forum, but safety isn't one of them. Just because people have a differing opinion on what is safe makes it silly ?

I was referring to the quibbling about 3 or 4 seconds, of F-150 PU or VW bug, that debate was silly bordering on stupid.
bumpy

[JRscooby]

fj12ryder wrote:
The 2 second rule is decent, but they say that stopping distance increases at about the square of speed. So if you're going twice as fast, the stopping distance is 4 times as long as it was at the slower speed. So you're probably right that the 2 second rule doesn't work as well at higher speeds.

Ok, your stopping distance increases on the square. Does the other guy's stopping stay at the same rate as his speed increases? The 2 seconds is the time for you to realize the car is slowing, and how fast, and get on the brake to slow your vehicle. The issue really gets bad is when the lead vehicle can slow at a faster rate. Sometimes a truck will hit a car, knock it well out in front of the truck, then hit it again.

[Thunderbolt]

Bumpyroad wrote:

toedtoes wrote:

Bumpyroad wrote:

toedtoes wrote:

Bumpyroad wrote:

toedtoes wrote:

They changed the wording from "at least one car length per every 10mph" to "at least three seconds" because it is easier to figure out.

I don't think that going down the road counting one thousand one, one thousand two, etc. and restart when another car pulls in front of you is easier than to estimate a car length behind a vehicle. in any event, there will not be any precision into any method is used to determine distance.
bumpy

Many people have difficulty estimating distances. And what "is" a car length? Is it a vw bug or a pickup or a sedan or a station wagon? Counting to three seconds takes those arguments out of the equation.

is that count to three, or one onethousand, two two thousand, etc.? what cadence do you use? when that car length was used many years ago I would assume that it was for a standard sized vehicle so it would probably equate to 1.273 of today's vehicle length.
bumpy :S

You're just being silly now. Is that 1.273 of a fiat or a Suburban?

I have to agree. this discussion is silly, bordering on stupid.
bumpy

Since when is a discussion on safe following distance silly ? There are many silly things discussed on this forum, but safety isn't one of them. Just because people have a differing opinion on what is safe makes it silly ?

[Thunderbolt]

Cummins12V98 wrote:
The braking and handling of cars now compared to 1973 when I took my Drivers Ed simply do not compare. 2 seconds then makes 2 seconds now much safer.

Our teacher had us set in a chair in front of the class one at a time. He held a yardstick by the tips of his fingers with it dangling to the left of our right foot at one foot off the ground. He would let go and the challenge was to hit the stick before it hit the ground once he let it loose. No one could do this. He used this as an example of how long it takes to react.

Great teacher, when traveling at 70 on I-5 he always kept on us saying "keep it on the top side of 70". It was actually scary doing so in a 72 LTD boat of a car going thru the curves along Lake Samish.

I know what you mean about the handling of the car. I learned in a 74 Dodge Monaco which is about the same. After driving one of those cars any new car today feels like a sports car.

[time2roll]

Car length maybe 18 feet max.

60 mph gives 108 feet by length, 264 with 3 seconds (88 fps)

Go with the three seconds.

[Bumpyroad]

toedtoes wrote:

Bumpyroad wrote:

toedtoes wrote:

Bumpyroad wrote:

toedtoes wrote:

They changed the wording from "at least one car length per every 10mph" to "at least three seconds" because it is easier to figure out.

I don't think that going down the road counting one thousand one, one thousand two, etc. and restart when another car pulls in front of you is easier than to estimate a car length behind a vehicle. in any event, there will not be any precision into any method is used to determine distance.
bumpy

Many people have difficulty estimating distances. And what "is" a car length? Is it a vw bug or a pickup or a sedan or a station wagon? Counting to three seconds takes those arguments out of the equation.

is that count to three, or one onethousand, two two thousand, etc.? what cadence do you use? when that car length was used many years ago I would assume that it was for a standard sized vehicle so it would probably equate to 1.273 of today's vehicle length.
bumpy :S

You're just being silly now. Is that 1.273 of a fiat or a Suburban?

I have to agree. this discussion is silly, bordering on stupid.
bumpy

[toedtoes]

Thunderbolt wrote:

MFL wrote:

Cummins12V98 wrote:
"but as you increase speed you also need more distance to give enough time to react"

My statement does exactly that! Faster you drive there will be more distance between you. Two seconds at 90 the distance between will be greater than at 55.

I stand by Mr Purvis' drivers ed recommendations many years later.

Exactly...I knew someone would question this, not thinking it through! I drove to drivers ed, but was not old enough to have a license yet. D's ed was fun, and I did learn from the experience.

Jerry

I have thought it through and regardless I stand by that 2 seconds will not be enough at greater speeds. Even though the distance will be greater I just don't see the increase being enough to compensate for the increased stopping distance it would take to react and actually stop if something happens in front of you. Most of the accidents as well as traffic jams I see on my 40 mile commute to work are from people following to close to the cars in front of them. I understand what you guys are talking about as I was taught the 2 second rule as well, but I just don't think it is enough at greater speeds. To each there own.

The rule is actually "at least three seconds" not "two seconds". As I mentioned above, the two seconds started being used to try to get commuters to back off the car in front of them without having them complain about other vehicles moving into that empty space.

The "at least" is to account for other factors - such as high speeds.

[toedtoes]

Bumpyroad wrote:

toedtoes wrote:

Bumpyroad wrote:

toedtoes wrote:

They changed the wording from "at least one car length per every 10mph" to "at least three seconds" because it is easier to figure out.

I don't think that going down the road counting one thousand one, one thousand two, etc. and restart when another car pulls in front of you is easier than to estimate a car length behind a vehicle. in any event, there will not be any precision into any method is used to determine distance.
bumpy

Many people have difficulty estimating distances. And what "is" a car length? Is it a vw bug or a pickup or a sedan or a station wagon? Counting to three seconds takes those arguments out of the equation.

is that count to three, or one onethousand, two two thousand, etc.? what cadence do you use? when that car length was used many years ago I would assume that it was for a standard sized vehicle so it would probably equate to 1.273 of today's vehicle length.
bumpy :S

You're just being silly now. Is that 1.273 of a fiat or a Suburban?