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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: 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