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Old January 25th, 2009, 03:24 PM   #561
ChrisZwolle
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Quote:
Originally Posted by pijanec View Post
What's the point to have a difference between normal expressways and expressways within built-up area? Wouldn't it be just easier to post speed limit signs if section needs lower limit?
Noise pollution. Many more people are living along expressways in urban areas, so more of them "suffer" from higher noise levels. (Although it's strange trains can blast at full speed through a town, creating high Lden dB levels.)

Also, if a road is busier, it's better to "calm" traffic somewhat by lower, but not repressive speed limits. Another problem is that urban expressways often have lower design speed limits.
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Old January 25th, 2009, 03:39 PM   #562
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He was asking why not just put speed-limit signs instead of that special urban sign.

Otherwise, Belgrade also has this sign, but it doesn't have some general speed limit, but 80-km/h sign beside.
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Old January 25th, 2009, 03:52 PM   #563
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Originally Posted by 909
However, for trucks and buses, the limits are lowered to 110, 90 and 80 km/h respectively
110 km/h for trucks? That must be about the highest truck limit in europe.
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Old January 25th, 2009, 04:10 PM   #564
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Well, most trucks are electronically limited to 93, and buses to somewhere about 100. So it's impossible to fulfill it technically (if keeping to the EU requirements). Bulgaria has limits for buses and trucks as follows:
bus truck automobile
built-up: 50 50 50
outside town: 80 80 90
motorway: 100 100 130
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Old January 25th, 2009, 04:12 PM   #565
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Quote:
Originally Posted by Verso View Post
He was asking why not just put speed-limit signs instead of that special urban sign.
Yes. Now drivers have to watch out for a sign with village name. Are at least those signs on sides of both lanes in particular direction?
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Old January 25th, 2009, 04:26 PM   #566
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^ I doubt any other cities have them but Bratislava and Belgrade, as far as Slovakia and Serbia are concerned.
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Old January 25th, 2009, 10:03 PM   #567
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Quote:
Originally Posted by pijanec View Post
This is unique in Europe. What's the point to have a difference between normal expressways and expressways within built-up area? Wouldn't it be just easier to post speed limit signs if section needs lower limit?
Actually, there are signs on merging lines which set 80 km/h speed limit. They are not necessary, but why not. Signs are also on the beginning of the motorway inside municipality.

The signs says Attention (80) Motorway inside municipality:



This is entrance to Bratislava from Győr and Vienna:

Original picture: http://static.panoramio.com/photos/original/2862879.jpg

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Originally Posted by pijanec View Post
Yes. Now drivers have to watch out for a sign with village name. Are at least those signs on sides of both lanes in particular direction?
Obviously they are on both sides. Nevertheless, you definitely don't have to watch out for a sign indicating you are entering Bratislava. The indication you are approaching the city looks like this and you will notice that for sure:


Last edited by Qwert; January 25th, 2009 at 10:08 PM.
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Old February 26th, 2009, 01:28 AM   #568
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Speed limit on the motorway: right or wrong?

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Old February 26th, 2009, 02:59 AM   #569
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My opinion:

All rural motorways should have recommended speeds posted, but no speed limit. Urban motorways should have speed limits only if absolutely necessary - for instance, to reduce congestion.
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Old February 26th, 2009, 05:01 AM   #570
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The main reason for speed limits is to make money from speeding fines. There are few places that actually need low speed limits.
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Old February 26th, 2009, 07:40 AM   #571
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I think there should be speed limits. Only very rural motorways with less than 35,000 vehicles per day could do without one.

I've seen what no speed limits do on busy freeways, people constantly accelerating from 120 to 180 and forced to break down due to slower people or trucks. It also encourages tailgating. Not everybody is comfortable driving at high speeds, and many cars don't even get high speeds, especially smaller ones and vans often don't reach more than 150 km/h. The lack of speed limits also reduces capacity, the highest capacity will be achieved around 90 km/h.

That said, I think many speed limits can be higher though. 100 km/h in rural areas make no sense, as do 80 limits on freeways in urban areas.

I've driven extensively in both France and Germany, but I felt way more comfortable in France, because in Germany you always got the feeling you're being pushed when overtaking a couple of trucks at 130 km/h.
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Old February 26th, 2009, 07:48 AM   #572
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This post was inspired from recent posts in the Belgium thread, about a .de driver being caught doing 246 km/h in .be and being fined 600 euro. Someone said that "[d]epending on when he did that, it could've been extremely dangerous".

I disagree with that. Going higher speeds on the motorways is not a danger factor. In fact, after having driven in .de, I believe that no speed limit actually encourages drivers to be more responsible, and, more important, MORE ALERT to what happens on the motorway. I believe one of the major factors in motorway accidents is boredom.
Are you kidding? At 250 km/h, one little pothole, or steering correction, and you'll fly into the center divided or ditch. 250 km/h = 70 meters per second. There's absolutely NOTHING safe about that, even not on deserted freeways. More alert at higher speeds, yes, but I think you're talking about speeds between 120 and 140, not 180+.
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Old February 26th, 2009, 08:22 AM   #573
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The speed limit serves no purpose here.

Its posted at 100km/h, but everyone is going at least 115-120. If you do less than 110 you'll probably get rammed! :-P

IMO the speed system in France works the best. 130 in good conditions, 110 in rain, 80 in hazardous conditions (like a blizzard or something).
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Old February 26th, 2009, 10:10 AM   #574
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Quote:
I've driven extensively in both France and Germany, but I felt way more comfortable in France, because in Germany you always got the feeling you're being pushed when overtaking a couple of trucks at 130 km/h.
It´s not a feeling it´s a fact. Especially cars with yellow plates make some German drivers mad and they keep pushin´. (Holländer schubsen)

In my opinion every human being should have the right to drive as fast as he wishes (on autobahns).
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Old February 26th, 2009, 01:47 PM   #575
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Quote:
Originally Posted by ChrisZwolle View Post
The lack of speed limits also reduces capacity, the highest capacity will be achieved around 90 km/h.
Ummm... you're wrong.
It's like in the basic flow area equation which states:
Q (m3/s) = v (m/s) * A (m2)
i.e. the flow is equal to speed times flow area section.
Obviously the higher the speed, the higher the capacity.

It's the same in the road capacity problem. Of course, one could say that increasing the speed also increases the mean inter-car distance, which reduces capacity. In a road with good flow and good driver behavior, the inter-car distance increase should be offset by the speed increase when it comes to computing flow.

Capacity of the road increases linearly with the speed of the cars. (Of course, if all drivers go at about the same speed, but this condition is necessary at any speed).

Last edited by wdw35; February 26th, 2009 at 02:18 PM.
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Old February 26th, 2009, 01:55 PM   #576
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Old February 26th, 2009, 02:11 PM   #577
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I sort of already thought my post could spark a discussion like this one ^_^;

About capacity: it's a bit unrealistic to think everybody is actually going to drive more than 130 km/h, so you'd end up with accidents due to people driving harder and people driving slower which in the end results in a grave loss of capacity.

Also, when driving faster you have to keep more distance between the car in front of you, which also results in less capacity.

I do agree with the speed difference depending on the weather conditions. There's only one problem: when exactly do you describe the weather as rainy? Some people say it's rainy when a drop of water falls from the sky, some say it's rainy when water is pouring down the sky. Only with a dynamic display system on the motorway that could become an objective system. Otherwise you'll only get discussions about whether it's rainy or not.

Greetings,
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Old February 26th, 2009, 02:15 PM   #578
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Those complaining about the speed limits in Europe should spare a thought for Australians. The maximum in most rural areas is 100km/h, with far fewer motorways and outback roads at 110km/h (and 130km/h only in the Northern Territory). And every time a speed limit changes, it gets slower. Its true the roads, drivers and vehicles are bad here. But this is in a country that is vast with long driving distances and few people or traffic in remote areas.

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Old February 26th, 2009, 02:16 PM   #579
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Driving on most German autobahns you have the choice of going either slow, or VERY fast, and moving between the two lanes is extremely dangerous. And if you drive at what is considered to be normal in the UK (130-140km/h) you have big mercs and audis up your arse. The autobahns are too busy on the whole to not have speed limits. I think only rural motorways in off peak periods with 3x3 lanes should have no limit.
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Old February 26th, 2009, 02:25 PM   #580
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Quote:
Originally Posted by wdw35 View Post
Ummm... you're wrong.
It's like in the basic flow area equation which states:
Q (m3/s) = v (m/s) * A (m2)
i.e. the flow is equal to speed times flow area section.
Obviously the higher the speed, the higher the capacity.

It's the same here. Capacity of the road increases linearly with the speed of the cars. (Of course, if all drivers go at about the same speed, but this condition is necessary at any speed).
Not true. Your model does not include safety issues, like spacing, and human factor. You cannot expect drivers to drive tight with little spacing at 200 km/h! Usually at very high speeds you have to mind greater spacing than at lower speeds, just for the sake of safety. Greater spaces means that you can squeeze less cars on the given stretch thus reducing capacity.

Another thing. Think of emergency braking. At higher speeds you are going to expect much more of that than at consistent but lower ones. Now when one driver just brake a little bit, another driver behind him is going to brake even harder, the same for all the drivers behind him. This will cause a chain reaction which will make cars decelerate drastically or even make them stop and create a jam. With lower speeds, driving is more predictable, which means less braking and more consistent flow of the highway.

Besides, there were several scientifical surveys carried out which revealed that optimal capacity is at around 80-90 km/h, as Chris mentioned.
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