Actually, traffic does behave like a liquid... kinda...
The traffic simulations I've seen use a particle model to work out traffic flows. The idea being that people over and under estimate the speed of their own car, and others on the road. The result of this is each car "vibrates" against others (with a certain air gap, hopefully).
The result of *that* is that traffic tends to slow *more* than the slowest driver would travel at. Which is why you get congestion at points of merging and corners for no apparent reason - nervous/careful people slow down, and it cascades into a near stop for everyone else.
Side note, slowing traffic down "for safety reasons" is inane. Traffic will slow itself down as volumes increase (eg, peak times) all you engineers have to do is make the road flow smoothly.
Which is why you get congestion at points of merging and corners for no apparent reason - nervous/careful people slow down, and it cascades into a near stop for everyone else.
You hit the nail on the head with that one. I really wish there was a way to keep people who are unaware of their impact on the flow of traffic off the freeway. Like the people who decide that it's time to go 40mph when they see their exit ahead. Just one of them can turn the right lane into one big clusterfuck real fast. Of course,
Part of this problem can be helped if people stop driving so close to the car in front. That way you can slow down a lot more gracefully and nobody needs to hit the brakes. This probably reduces overall speed but it does mean a more consistent slightly slower speed than fast sections between jams.
Speeding does slow you down. Especially when it's significantly faster than the limit/traffic flow.
The reasoning is simple, there are enough people who don't want to get ticketed, die in a car wreck, ect. that when you are trying to maintain the high rate of speed you will eventually have to go around one of them, and sooner or later you will get stuck in the outside lane by one. The outside lane is called the slow lane for a reason. By the time you Unstick yourself the cars you were in front of in the
I mostly agree with you. My motto is "drive smarter, not faster", but it includes driving a bit faster when it will mean not having to stop at a light. This is in opposition to the people who drive with their balls instead of their brains. I know you're familiar with their habits.
The freeway is a bit different. Since there are no lights forcing you to stop every block or three, going fast can make a signifigant difference in travel time. (Even five miles per hour over the limit adds up if you can maintain
Anyone who routinely uses the brake on the motorway/freeway is not a competent driver.
That's exactly what they taught me in driving school. Of course, they also scared me shitless by making me drive a non-roadworthy vehicle on the freeway during rush hour.... o_O
This is really easy to work out.
If we select describe the mean journey length, l, and we have a maximum speed s, then the journey time t = l/s.
If we decrease the maximum speed, then we can see that this increases the mean journey time.
People will start there journeys at different times. This means that there will be a rate of journeys being started, and they will exist for a time (mean journey time).
A journey, means a car on the road.
If you increase the amount of time a journey takes, you must inc
It's not that simple. The stoping distance increases with speed, so therefore the space taken up by a car will increase. Secondly, unless you drive at a constant speed at all times, the algorithm to calculate your time on the road is not correct. It is possible that when speeding your journey will take exactly the same time.
Yeah, I know it's not *that* simple, but I guess what I was getting at, is that even with an incredibly simple model (increase speed, reduce journey time), this is affected by the increased severity of accidents - which represent a critical failure of the road network.
But the algorithm is correct in its own terms (mean journey length, speed limit) means that there is a minimum mean time a journey can take.
But of course traffic behaves like the weirdest fluid ever. It doesn't just expand and contract at
Speeding does slow you down. Especially when it's significantly faster than the limit/traffic flow.
The reasoning is simple, there are enough people who don't want to get ticketed, die in a car wreck, ect. that when you are trying to maintain the high rate of speed you will eventually have to go around one of them, and sooner or later you will get stuck in the outside lane by one. The outside lane is called the slow lane for a reason. By the time you Unstick yourself the cars you were in front of in the
Doesn't slower speed increase congestion? (Score:2, Funny)
Re:Doesn't slower speed increase congestion? (Score:0)
This is one of those cases. If traffic was a liquid flowing smoothly through a pipe, then it would be. But traffic does not behave like a liquid.
Re:Doesn't slower speed increase congestion? (Score:5, Informative)
The traffic simulations I've seen use a particle model to work out traffic flows. The idea being that people over and under estimate the speed of their own car, and others on the road. The result of this is each car "vibrates" against others (with a certain air gap, hopefully).
The result of *that* is that traffic tends to slow *more* than the slowest driver would travel at. Which is why you get congestion at points of merging and corners for no apparent reason - nervous/careful people slow down, and it cascades into a near stop for everyone else.
Side note, slowing traffic down "for safety reasons" is inane. Traffic will slow itself down as volumes increase (eg, peak times) all you engineers have to do is make the road flow smoothly.
Re:Doesn't slower speed increase congestion? (Score:1)
You hit the nail on the head with that one. I really wish there was a way to keep people who are unaware of their impact on the flow of traffic off the freeway. Like the people who decide that it's time to go 40mph when they see their exit ahead. Just one of them can turn the right lane into one big clusterfuck real fast. Of course,
Re:Doesn't slower speed increase congestion? (Score:1)
Re:Doesn't slower speed increase congestion? (Score:2)
The reasoning is simple, there are enough people who don't want to get ticketed, die in a car wreck, ect. that when you are trying to maintain the high rate of speed you will eventually have to go around one of them, and sooner or later you will get stuck in the outside lane by one. The outside lane is called the slow lane for a reason. By the time you Unstick yourself the cars you were in front of in the
Re:Doesn't slower speed increase congestion? (Score:1)
The freeway is a bit different. Since there are no lights forcing you to stop every block or three, going fast can make a signifigant difference in travel time. (Even five miles per hour over the limit adds up if you can maintain
Re:Doesn't slower speed increase congestion? (Score:2)
Anyone who routinely uses the brake on the motorway/freeway is not a competent driver.
Re:Doesn't slower speed increase congestion? (Score:1)
That's exactly what they taught me in driving school. Of course, they also scared me shitless by making me drive a non-roadworthy vehicle on the freeway during rush hour.... o_O
Slower speed does increase congestion...but (Score:1)
Re:Slower speed does increase congestion...but (Score:1)
Re:Slower speed does increase congestion...but (Score:1)
Re:Slower speed does increase congestion...but (Score:3, Insightful)
The reasoning is simple, there are enough people who don't want to get ticketed, die in a car wreck, ect. that when you are trying to maintain the high rate of speed you will eventually have to go around one of them, and sooner or later you will get stuck in the outside lane by one. The outside lane is called the slow lane for a reason. By the time you Unstick yourself the cars you were in front of in the
Re:Doesn't slower speed increase congestion? (Score:2)
Traffic Waves [amasci.com].