It's not about whether the car can handle the speed in terms of power or grip - it depends on other factors. For one thing, at closing speeds of 100mph, every little miss can lead to hitting the guardail. There's also the effect of wind gusts (even from other cars), changes in the light in different times of day and when passing through shaded road parts or tunnels, and other effects to bear in mind.
Also, cars aren't made to withstand hits at anywhere near those speeds, so it's best not to reach them. These speeds are also faster than the flow of traffic and cause conflicts with naturally slower traffic like trucks, with merging traffic and with the potential presence of stalled cars, pedestrians and wildlife.
Also, if traffic is moving at such speeds, than lack of safe margins in between cars become much more common because the proper distance would seem very large and because of dramatic changes in stopping distances between cars with different braking abilities, and any little inaccuracy in maintaining a safe gap would end with a very serious collision.
It's reasonable to say that the speed limit on some highways are currently set too low. It is not so reasonable to say that the absolute speed on open highways does not matter. In particular, one should distinguish between some highways which are little more than dual-carriageways and a proper motorway which yields a few extra characteristics to allow even higher speeds.
Furthermore, in many countries, it would seem like the regulators are too quick to crown dual-carrigeways as proper motorways - with very little to support this decision.
Of course, any kind of speeds - even up to the limiter - is not very substantial in terms of collisions on the road, surely not when compared to speeding in school areas and residential streets. But it still is something to consider.
In my book, a reasonable speed limit to yield is something like what is customary in most European roadways:
1. School areas and little streets: 15mph
2. Residential streets: 25mph
3. Town roads: 30mph
4. Dual-Carriageway: 60mph
5. Motorway: 80mph
Safe speed should be slightly under your skill level, equipment capability, and road conditions. For the last 10 years I have limited myself to driving no more than 8/10ths. I will now reduce that to 7/10ths. That still puts me ahead of most of the "steerers" as opposed to actual drivers.
"7/10ths is good for track days - but it does not offer the necessary safety margins on normal roads. I would consider 6/10ths as the most high limit of performance for road driving".
Astraist: I may not have a good comprehension of 10ths. On track days I would consider 7/10s would put a skilled race driver at the back of the pack. Slightly short of 10/10ths would put the skilled race driver in the lead. My definition of 8/10ths is taking curves at the maximum speed, for driver skill and road conditions while staying in your lane and not breaking traction with any wheel and staying at or below the posted speed. Because of my age I have lowered my threshold to 7/10ths. At 8/10ths I had to disable traction control. At 7/10ths I can leave it engaged. I was not advocating driving at 70% of your vehicles maxiimum speed. 130mphX70%-91mph.
sgtrock21 wrote:
I remember reading a study of "drivers" tolerance (when they became uncomfortable) of lateral "G" force. The average was .27 "G"! I don't think I could feel .27 "G" of lateral accelleration!!! The worst handling vehicles sold in the U.S. are capable of .75 "G"! !
Handling has nothing to do with the G-force you can experience. G-forces are all up to the grip the car can generate and how much it's chasis can withstand and last but not least - how aerodynamic it is. A car could never exceed one G unless it has somekind of aerodynamic assistance.
Astraist: I agree. Some vehicles that can approach 1.0 latteral G on a skidpad are "evil" when it comes to handling on the street.
sgtrock21 wrote:
My biggest problem with excessive speed is residential streets. I have seen vehicles speeding up to 50mph in a 25mph zone. There are children playing in these speed zones! I am very sensitive to this. In 1973 I was going between 25 or 30 mph on a residential street. A 4 y/o boy ran into the street from between parked cars. I locked the brakes but still punted him about 40 feet. Fortunately he survived with a broken arm and major road rash. I tend to drive less than 25mph on residential streets since that accident.
Excessive speed relative to the road conditions (And driver, and car and etcetra) is a problem everywhere: In residential streets, in main city roads, in single-carriageways and in highways.
Even an open highway does not justify driving at speeds such as 100mph or more. In particular, many highways don't have the necessary conditions the be considered motorways or autostrades - like wide shoulders, special guardrails, open curves and protection against animals entering the road - so they require even slower speeds.
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