Let's devise a sensible national speed limit
Discussion
Assuming there should be a speed limit on roads, let's see if we can think of one on first principles that should not be exceeded on any road whatsoever.
I will start with Mach 1. Firstly, this creates a sonic boom, so is f
king loud. Secondly, it prevents anyone from being able to hear oncoming traffic. Therefore this speed should be illegal in all circumstances on the public highway.
I suspect the next obvious higher bound will be related to the ability of the human eye to pick up an obstacle on the highway that could materially interfere with the car. Be nice if other folk with more knowledge could work that one out for me, otherwise I shall do it later.
Any more ideas to create an upper bound?
I will start with Mach 1. Firstly, this creates a sonic boom, so is f
king loud. Secondly, it prevents anyone from being able to hear oncoming traffic. Therefore this speed should be illegal in all circumstances on the public highway.I suspect the next obvious higher bound will be related to the ability of the human eye to pick up an obstacle on the highway that could materially interfere with the car. Be nice if other folk with more knowledge could work that one out for me, otherwise I shall do it later.
Any more ideas to create an upper bound?
Another idea that came into my head: It has to be possible for observers to be able to gauge your speed before pulling out in front of you, without risk of collision. Again, I can work this out on Sunday if I really have to, but would prefer it if someone else could. This will quite possibly lead to different speed limits in different lane-d carriageways.
I want to be clear that this is not a sensible attempt to set a national speed limit; I don't believe that there should be any such thing. But if there is to be such a thing, it ought to be a speed which it is always unsafe to exceed. Sixty or seventy are pathetic jokes... there is no way that anything less than three hundred is justifiable.
I want to be clear that this is not a sensible attempt to set a national speed limit; I don't believe that there should be any such thing. But if there is to be such a thing, it ought to be a speed which it is always unsafe to exceed. Sixty or seventy are pathetic jokes... there is no way that anything less than three hundred is justifiable.
Edited by Somewhatfoolish on Friday 25th February 20:36
hehe, just thought of another one
has to be less than mach 0.5. Otherwise the top end of your wheel is travelling supersonic. Or have I not thought this through properly?
edit: no I haven't thought that through properly. It's rubbish. But leaving it as an example of the kind of things we need to think of!
has to be less than mach 0.5. Otherwise the top end of your wheel is travelling supersonic. Or have I not thought this through properly?
edit: no I haven't thought that through properly. It's rubbish. But leaving it as an example of the kind of things we need to think of!
Ive never understood why NSL cant be No Speed Limit. I mean almost all NSL roads are relatively well sighted, reasonably straight roads. As long as you're not suicidal, you should be able to judge how fast you can go before it all gets a little bit silly.
It might also make people think twice about blindly pulling out of junctions, and force them to pay attention when driving.
Of course it'll never happen because most drivers these days seem to struggle to breathe and turn the round shaped object in front of them
It might also make people think twice about blindly pulling out of junctions, and force them to pay attention when driving.
Of course it'll never happen because most drivers these days seem to struggle to breathe and turn the round shaped object in front of them
Current tyre technology seems to hit a wall around 300mph or so; you'd more or less need to be running on solid rubber after that and it wouldn't be nice.
But that's not really the issue; braking is. Most of the motorways are "safe" to drive on at 90mph, the difficulty arises due to the big speed differentials between cars and trucks at that point, especially if one pulls out to overtake. So you want your average car to brake as quickly from whatever speed it's doing to a stop as cars do now from 90. That'll need aero braking of some kind, to reduce the load on the tyres and brakes. You could probably get an extra g of deceleration that way. If your car is a gas turbine range extended hybrid you could always deploy reverse thrust too.
But that's not really the issue; braking is. Most of the motorways are "safe" to drive on at 90mph, the difficulty arises due to the big speed differentials between cars and trucks at that point, especially if one pulls out to overtake. So you want your average car to brake as quickly from whatever speed it's doing to a stop as cars do now from 90. That'll need aero braking of some kind, to reduce the load on the tyres and brakes. You could probably get an extra g of deceleration that way. If your car is a gas turbine range extended hybrid you could always deploy reverse thrust too.
davepoth said:
...
...the difficulty arises due to the big speed differentials between cars and trucks at that point, especially if one pulls out to overtake...
There's some merit in passing the truck reasonably quickly so you spend less time along side, in the blind spot, etc. I agree that the differential between 90 and 56 is a bit too much, especially on 2 lane dual carriageways, but I also feel it to be a little too low sometimes when travelling within the 70 limit....the difficulty arises due to the big speed differentials between cars and trucks at that point, especially if one pulls out to overtake...
So perhaps an 80 limit on 2 lane DCs/motorways and a 90 on 3 lane DCs/motorways.
I tend to go slower these days anyway due to the fuel prices and a tight wallet! I'll still apply the odd burst of speed to avoid 'elephant racing' with trucks, as I think I'd come out worse in an altercation!
Somewhatfoolish said:
I will start with Mach 1.
As an absolute speed this will vary throughout the day, the year, the latitude and the height of the road (the speed of sound through air is affected by temperature). This variability will give vonhosen palpitations.Somewhatfoolish said:
It has to be possible for observers to be able to gauge your speed before pulling out in front of you, without risk of collision.
The Germans do OK with speed differentials of over 100mph. But the issue is not so much with a slower driver gauging the speed of an approaching vehicle that one can see, as with seeing an approaching vehicle that is travelling at very high speed in sufficent time to take appropriate action (and v.v.).Streaky
Funkateer said:
So perhaps an 80 limit on 2 lane DCs/motorways and a 90 on 3 lane DCs/motorways.
Ordinary DC with no hard shoulder 70 is about max ( even for the 3 lane ones) DC with a hard shoulder same as motorway = 80.Easy way is to check the traffic speeds. The A74M/M74M has mean speeds of around 74 ( lovely symmetry), so the limit ought to be 80.
Monkeylegend said:
It would probably be unsafe to exceed the speed of light so I propose 186,000 miles per second, or what ever it is. Should make the world a smaller place.
Not so sure about fuel consumption though.
What about if we abandoned relativity?Not so sure about fuel consumption though.
We'd have to travel at 67,000 mph to stand still
saaby93 said:
Monkeylegend said:
It would probably be unsafe to exceed the speed of light so I propose 186,000 miles per second, or what ever it is. Should make the world a smaller place.
Not so sure about fuel consumption though.
What about if we abandoned relativity?Not so sure about fuel consumption though.
We'd have to travel at 67,000 mph to stand still
Slightly OT I know, but interesting none the less.
Funkateer said:
davepoth said:
...
...the difficulty arises due to the big speed differentials between cars and trucks at that point, especially if one pulls out to overtake...
... I agree that the differential between 90 and 56 is a bit too much, especially on 2 lane dual carriageways, but I also feel it to be a little too low sometimes when travelling within the 70 limit....the difficulty arises due to the big speed differentials between cars and trucks at that point, especially if one pulls out to overtake...
So perhaps an 80 limit on 2 lane DCs/motorways and a 90 on 3 lane DCs/motorways...
Monkeylegend said:
I seem to recall reading somewhere a proposal to reduce travel times by flying straight up to the edge of space, hovering whilst the earth rotated below you, then coming straight back down again when your targetted destination was below you. You could get from here to New Zealand in 90 mins or so apparantly.
Slightly OT I know, but interesting none the less.
Would still take 12 hours to get to the opposite side though.Slightly OT I know, but interesting none the less.
If people were trained properly then I don't see any reason why NSL couldn't equal No Speed Limit. Or even no speed limits anywhere, with it being up to the judgement of the driver what is a reasonable speed.
But with the average standard of driving on the roads, I think the current limits are about right.
But with the average standard of driving on the roads, I think the current limits are about right.
streaky said:
Somewhatfoolish said:
I will start with Mach 1.
As an absolute speed this will vary throughout the day, the year, the latitude and the height of the road (the speed of sound through air is affected by temperature). This variability will give vonhosen palpitations.Monkeylegend said:
Mr Sparkle said:
Monkeylegend said:
I seem to recall reading somewhere a proposal to reduce travel times by flying straight up to the edge of space, hovering whilst the earth rotated below you, then coming straight back down again when your targetted destination was below you. You could get from here to New Zealand in 90 mins or so apparantly.
Slightly OT I know, but interesting none the less.
Would still take 12 hours to get to the opposite side though.Slightly OT I know, but interesting none the less.
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