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from the youtube-dashcam-accidents-guaranteed-for-years-to-com dept.
Sunday Times Driving reports under 50% of surveyed UK drivers know what a roundabout sign looks like, and only 68% knew what the speed bump sign means.
The survey was conducted by the Institute of Advanced Motorists, with 1,000 participants.
Only 32% of drivers knew you should allow at least a two-second time gap to the vehicle ahead when driving on a dry open road. It appears many motorists are conflating this with two car lengths in distance, as 53% of those surveyed responded with that answer.
[...] Younger motorists were the most likely to answer incorrectly, with 17 to 39 year-olds having the lowest correct answer percentage rates in 14 of the 23 questions, but older drivers didn't do very well either.
The Sunday Times article has an embedded googleforms survey, so you can test your knowledge of UK road rules.
(Score: 4, Disagree) by Dr Spin on Monday October 22 2018, @09:03AM (20 children)
If they want us to have 2 seconds from the car in front, they will need 50% more road capacity. If I leave a gap of 2 secs between me and the car in front, it only takes another second before there is a car in it.
Half the problem is that reducing speed limits and closing off side roads has halved road capacity, which has the same effect as doubling the number of cars on the road.
The effect on pollution is even worse, as the traffic grinds to a halt causing pollution without actually moving at all.
I live in London - and the Mayor (Saddiq, Boris, and Ken) are the responsible idiots.
Warning: Opening your mouth may invalidate your brain!
(Score: 5, Insightful) by shrewdsheep on Monday October 22 2018, @09:24AM (12 children)
I challenge this opinion. Road capacity ist the product of vehicle density and average speed. I claim that road capacity is actually maximal at 2 second distance between cars, guaranteeing laminar flow. The lack of discipline of drivesrs, not heeding the 2 second rule, leads to drastic reduction in average speed (turbulent flow, a.k.a. stop and go).
(Score: 3, Informative) by isostatic on Monday October 22 2018, @09:38AM (10 children)
1 car every 2 seconds at 30mph is 1800 cars an hour
1 car every 1 second at 30mph is 3600 cars an hour
(Score: 4, Informative) by c0lo on Monday October 22 2018, @09:59AM (5 children)
That's the theory.
The practice shows that, with 30kph speed limit, at 1 second distance between cars, the actual speed drops to 20 kph.
Before Mythbusters the japanese replicated it [youtube.com]
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 3, Touché) by isostatic on Monday October 22 2018, @10:12AM (3 children)
Assuming a car is 4m long, and the gap is measured from the back of the leading car to the front of the trailing car.
At 20kph (5.5m/second), and a 1 second gap, that's 9.5m for each car + gap, or 2105 cars an hour
At 30kph (8.3m/sec), and a 2 second gap, that's 20.7m for each car + gap, or 1450 cars an hour.
Therefore by your own figures, you get more cars on the road with a 1 second gap than a 2 second gap.
(Score: 5, Touché) by Phoenix666 on Monday October 22 2018, @01:18PM
In practice, merges cross everyone up. If you don't have a 2 second gap, people have trouble merging. When people have trouble merging, or changing lanes, they have to force their way in. Then everything jams up and cheaters want to jump in at the head of the line. Everything stops. So, yes, maybe you have more cars on the road, but none of them are moving.
It's far more efficient to keep adequate spacing. It's far less stressful if traffic moves at a constant speed, instead of stop-and-go.
Washington DC delenda est.
(Score: 5, Insightful) by darkfeline on Monday October 22 2018, @02:03PM (1 child)
In theory, practice and theory are the same. In practice, they are different.
Crunching numbers like you're doing is a pointless exercise since you lack a model that was derived from actual observation of traffic flow.
Join the SDF Public Access UNIX System today!
(Score: 2) by Reziac on Tuesday October 23 2018, @05:24AM
As I was about to say, there speaks someone who has never driven in Los Angeles, where we think bumper-to-bumper at 70mph is normal, tho it scares the shit out of the uninitiated.
And there is no Alkibiades to come back and save us from ourselves.
(Score: 2) by FatPhil on Monday October 22 2018, @01:52PM
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 3, Insightful) by Nuke on Monday October 22 2018, @12:04PM (2 children)
No, because of dynamic instability. When cars are closer, someone slowing down slightly (for whatever reason, including a driver's inability to maintain a constant speed) causes the car behind to slow typically even more, and the effect can build up back along the line until at one point the traffic stops completely - long after the driver who triggered it all has gone on, and got home. I used to watch this happen when I lived on a high floor overlooking a busy road leading into a city.
(Score: 2) by mhajicek on Monday October 22 2018, @02:27PM (1 child)
Around here people typically drive 80mph with about a half second following distance. How does that affect your numbers?
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
(Score: 2, Touché) by Anonymous Coward on Tuesday October 23 2018, @12:23AM
It's usually fine until one of them arse ends the guy in front and the entire lane is out of commission turning the freeway into a giant parking lot.
(Score: 1) by nitehawk214 on Monday October 22 2018, @06:05PM
1 care every 1 second at 30mph on a highway is probably going to cause people to constantly slam on the brakes causing pressure wave traffic jams.
"Don't you ever miss the days when you used to be nostalgic?" -Loiosh
(Score: 3, Interesting) by Dr Spin on Monday October 22 2018, @09:33PM
Road capacity ist the product of vehicle density and average speed. I claim that road capacity is actually maximal at 2 second distance between cars, guaranteeing laminar flow. The lack of discipline of drivesrs, not heeding the 2 second rule, leads to drastic reduction in average speed (turbulent flow, a.k.a. stop and go).
I am claiming that there are two problems here:
1) lack if discipline (or possibly sanity) is fairly common amongst drivers
2) as a driver, I do not have the ability to maintain a 2 second separation, because if I create a two second separation, someone fills it, because he would prefer a one second separation between himself and me to the 0.7 second separation he had between himself and the other cars in the lane he was previously in.
The fact is that vast amounts of road capacity have been removed by "traffic calming" measures (which mostly appear likely to incite road rage) means the result of dividing the length of the road by the total number of cars on the road does not leave much distance to spare.
If my journey takes 10 minutes, then I use the road for ten minutes. If I (and all other road users) am slowed till my journey takes 20 minutes, then there will be twice as many cars on the road if they all attempt to make the same journey at the same time.
If you wish to travel along the Lea Bridge Road in the rush hour (previously 30MPH limit), you would have done well to average 20 MPH. Now it has a limit of 20MPH, you will be passed by heavily pregnant women pushing push chairs through the pollution. I have no doubt that someone thinks this is an improvement in our standard of living, but who ever he is, he does not go down the Lea Bridge Road on foot, in a car or on a bus. (Maybe he is confined to a mental hospital - I do not know). Perhaps he is one of the bikers who do 50MPH on the wrong side of the road?
Disclaimer: I have a Freedom pass, and and therefore use the bus - unless it is quicker to walk - which it mostly is in the "rush hour".
Warning: Opening your mouth may invalidate your brain!
(Score: 2) by isostatic on Monday October 22 2018, @09:41AM
If they want us to have 2 seconds from the car in front, they will need 50% more road capacity. If I leave a gap of 2 secs between me and the car in front, it only takes another second before there is a car in it.
And where does that car come from?
If you have 3 motorway lanes at the usual 50-60mph in heavy traffic, and someone pulls into your lane, that just leaves a gap in the other lanes. Eventually that person will pull out and you'll be back to where you stated.
It's really unintuitive, but traffic is. http://www.smartmotorist.com/traffic-and-safety-guideline/traffic-jams.html [smartmotorist.com] for some interesting views.
(Score: 2) by MostCynical on Monday October 22 2018, @10:09AM (5 children)
Half a second to notice, half a second to fail to react fast enough, and to say "oh, sh.." while ploughing into a stopped car in front..
Here, have some online reaction tests:
online reaction test [justpark.com]
One Australian state's pratice test [nsw.gov.au]
"I guess once you start doubting, there's no end to it." -Batou, Ghost in the Shell: Stand Alone Complex
(Score: 0) by Anonymous Coward on Monday October 22 2018, @12:39PM (1 child)
thank you for the online reaction test thing.
I had 3 tries.
First one got me 72.
Second got me 28.
Third one they said "we're not sure you're human".
I'll be expecting my driver's license in the mail now...
(Score: 2) by dry on Tuesday October 23 2018, @05:30AM
I got an offer to safe a swf file.
(Score: 2) by bob_super on Monday October 22 2018, @06:22PM (1 child)
If you are a second behind a stopped car, and you're not already swerving, stopping or stopped, you shouldn't be on the road.
I tend to leave more distance between me and the car in front, if they block my view (fucking SUVs and pickups) or if they can stop much faster than me (sports cars). Being 1 second behind an 80000 lbs truck is stupid, but it's a lot safer than 1s behind an empty F150.
(Score: 2) by Reziac on Tuesday October 23 2018, @05:31AM
Unless you've got superbrakes like they put on the F350. I've been quite shocked at how fast that durn thing can stop (way faster than my old F100). As discovered when some fuckwit pulled out in front of me and I had to go from 30 to zero in half a second to avoid T-boning him, however richly deserved.
And there is no Alkibiades to come back and save us from ourselves.
(Score: 0) by Anonymous Coward on Tuesday October 23 2018, @05:25PM
It keeps saying I'm not human if I use the keyboard... I suspect my reflexes are about average for a healthy person and the real reason is most people use crap hardware (high latency monitors and input devices).