Speed limits

Car length maybe 18 feet max.

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

Go with the three seconds.

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

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.

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?

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

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.

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.

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.

valhalla360 wrote:

toedtoes wrote:
You are making your own conclusion that hasn't been shown.

The data shows that you are more likely to Be IN A COLLISION if driving at the much slower speed. It does NOT show that the slow driving person is the CAUSE of the collision. Per the data from the NHTSA study, the CAUSE of that collision is most likely because the other driver was distracted, speeding, tailgating, not correctly judging the amount of space, overcorrecting, falling asleep, etc.

You are still focused on finding fault. I'm talking about eliminating accidents. I don't care about "fault" I want to eliminate crashes.

I want to enjoy driving and eliminating crashes is not that terribly important to me. Reducing speed limits for everyone because we know that some are texting while driving or for some other reason are incapable of driving 80 mph down a divided highway is frustrating. Occasionally we drive in a small city that has determined that some people are incapable of safely making left hand turns at uncontrolled intersections … they’ve got concrete curbs poured all over everywhere forcing traffic to make safe right hand turns…. I find driving to be getting more and more frustrating the safer it gets.

valhalla360 wrote:


Speed certainly isn't the only reason for crashes but it's been decades where it has been beaten into the American conscious that "speed kills", so not surprising, no one "claimed" is was low speed.

Increase space sounds good but in foggy conditions, if you slow down more than most, that means you have more interactions with cars passing you (or creating long lines of closely spaced cars behind you). It's not a simple problem for a human driver to solve but if you are doing 25mph in a 70mph zone because of visibility, you should be getting off the road entirely (short of an emergency). Adaptive speed control that can see thru fog and react more quickly is our best bet for solving low visibility issues.

Pile ups in foggy conditions are not because ONE person was driving 25. It is because too many people are driving 70 and driving too close to one another - all it takes is one vehicle to change lanes and a single car to hit their brakes and the chain reaction begins. None of those vehicles has enough space at the speeds they are driving to avoid hitting the car in front of them.