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Old July 24th, 2007, 04:18 AM   #901
Nephasto
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The cars may be safer, but everythink still ocurrs much faster when you're driving at 150 than when driving at 100.

I'm not an appologist of low speed limits or anything, just to point out that no matter how you try to spin it, driving a car at 150km/h is considerably more dangerous than driving at 100km/h.

Anyway, in a rural stretch of a freeway, with not too much traffic its definatly much better to drive at 150 than at 100, no doubt.
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Old July 24th, 2007, 04:22 AM   #902
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Quote:
Originally Posted by geogregor View Post
In Germany where there is no limit on freeways is less accidents than in many countries which have limits.
Indeed. But for a good comparison you would have to compare nowadays Germany (with no speed limit) with Germany with a 130km/h speed limit.

It certainly wouldn't be more dangerous. But it might not be that much safer(less deaths) either...
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Old July 24th, 2007, 08:41 AM   #903
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Quote:
Originally Posted by Tom Marney View Post
The reason speed limits are still low in some places is that lower speed limits significantly improved safety.
I am not an expert in statistics, but to make that assumption, I think they should compare the number of accidents when the limit was higher and when it was lower. I don't know of many instances when the speed limits went from higher to lower given exactly the same conditions. Last time it happened more than 30 years ago, but then the cars and the roads were of significantly different quality than today. For instance, how can Hawaii assume that the limit of 60 mph significantly improves safety compared to higher limits if the latter have never been tried before?
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Old July 29th, 2007, 09:04 PM   #904
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Quote:
Originally Posted by Chris1491 View Post
The Danish risen the speed limit from 110 to 130 a few years ago, resulting in less accidents. I think, that with a low speed limit, people are paying less attention.
Could you get me a source, because i'm always in a discussion about the speedlimits in the Netherlands. I'm pro higher speed limits and they are strongly against.

Also can someone give me legal minimal width of an interstate freeway? I also think the 3,5m width that we use in The Netherlands is not sufficient anymore.

Also every complaining about freeways of being old/outdated is a fool. Environmental issues will be handled in the upcoming century so that wont be a argument/excuse for building more freeways/interstates. Also saying it's old compared to other ways of transport then you havent paid much attention at school. Trains/railway transportation systems are extremely old compared to freeways (about 4/5 times older). Also subways are old compared to freeways (about 2/3 times older), it's the same for trams and even airplanes/airports are older than the interstate system.
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Old July 29th, 2007, 09:11 PM   #905
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Check this topic on the Dutch Motorway forum. Increasing speed limit from 110 to 130 caused 25% less traffic deaths.
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Old July 29th, 2007, 10:15 PM   #906
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Quote:
Originally Posted by Alex Von Königsberg View Post
I am not an expert in statistics, but to make that assumption, I think they should compare the number of accidents when the limit was higher and when it was lower. I don't know of many instances when the speed limits went from higher to lower given exactly the same conditions. Last time it happened more than 30 years ago, but then the cars and the roads were of significantly different quality than today. For instance, how can Hawaii assume that the limit of 60 mph significantly improves safety compared to higher limits if the latter have never been tried before?
Surely the states that kept their speed limits lower did exactly that, don't you think? Not that I blindly trust the judgements of highway agencies-- far from it, actually--, but low speed limits tend to be unpopular, and the political decision to keep them low isn't taken lightly. Then again, it isn't just motorists who pay the bills for accidents-- insurance companies, healthcare providers and government itself are interested parties, and they have political power, too.

OTOH, it doesn't surprise me that in some cases, lower speed limits have a negligible impact on accident rates. A verifiable reduction is hard for me to believe, though. If anyone posts a link to a study documenting reduced accident rates after a rise in speed limits, I'll read it, but I'm not interested enough to do it on my own.

I did once read a study that indicated that so-called safety improvements-- straightening sharp curves, flattening blind hillcrests, etc., had no overall impact on safety, apparently because these improvements simply allowed motorists to become less attentive. More interestingly, the study found that while there was a decline in the overall severity of accidents, the decline was less than what could be reasonably attributed to better cars and emergency medical care, so a statistical case could be made that so-called safety improvements actually made conditions less safe!
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Old July 29th, 2007, 10:29 PM   #907
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Speed difference is a major factor on deadly accident. If the speed limit is lowered, but high speed drivers remain high speeding and more people drive slower, it wouldn't help the situation. If someone decides to drive 80-90mph, they are not going to slow down because the posted speed limit is lowered from 65 to 55mph. As long as it's free flow traffic on the highway, those people who are driving fast are going to drive fast as they are now. The only way to slow everyone down is really put the speed limit in enforcement, more restrictive than today.
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Old July 29th, 2007, 11:06 PM   #908
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Maybe, but in France, the limit is 130km/h (quite fair), very few enforcement, but you generally don't see cars flying low by all the time, in opposite to Germany, where on quiet Autobahns, cars easy drive in the 200's.

So i say, on rural interstates with lower AADT than 80.000, the speed limit can easily be set on 75 or 80 MPH. But i would set a lower speed limit for trucks, driving above 60MPH isn't very fuel economic for trucks.

What fuel are US trucks driving on anyway?
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Old July 30th, 2007, 04:20 AM   #909
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Quote:
Originally Posted by Tom Marney View Post
I did once read a study that indicated that so-called safety improvements-- straightening sharp curves, flattening blind hillcrests, etc., had no overall impact on safety, apparently because these improvements simply allowed motorists to become less attentive. More interestingly, the study found that while there was a decline in the overall severity of accidents, the decline was less than what could be reasonably attributed to better cars and emergency medical care, so a statistical case could be made that so-called safety improvements actually made conditions less safe!
Well,I don't buy that.
If how have a road where there are certain points were there are many accidents, and you correct them, those points of concentration of accidents will no longer exist and the road will become safer.
That was done for example here in Portugal in IP4 and IP5 with very good results! With very significant reductions in road casualties in those roads, after the improvements were made.



Quote:
Originally Posted by Chris1491 View Post
So i say, on rural interstates with lower AADT than 80.000, the speed limit can easily be set on 75 or 80 MPH. But i would set a lower speed limit for trucks, driving above 60MPH isn't very fuel economic for trucks.
I'd say that practically any rural interstate will have an AADT way below 80000.
Taken into account that 80000 is a very high traffic volume (minimum 3 lanes, 4 recommended). Here in Portugal for example we only have such values of traffic intensities in urban freeways of Porto and Lisbon.
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Old July 30th, 2007, 07:12 AM   #910
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Quote:
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What fuel are US trucks driving on anyway?
Diesel, natürlich! Do you know how much benzine those 18-wheeler monsters would eat?
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Old July 30th, 2007, 01:41 PM   #911
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But the real question here is, why aren't the authorities increasing the speed limit to 130 km/h (85mph?) everywhere?
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Old July 30th, 2007, 05:10 PM   #912
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Quote:
Originally Posted by Nephasto View Post
Taken into account that 80000 is a very high traffic volume (minimum 3 lanes, 4 recommended). Here in Portugal for example we only have such values of traffic intensities in urban freeways of Porto and Lisbon.
Nah, most rural motorways in the Netherlands have around 60.000 - 100.000 vehicles a day, and you'd better don't expect 2x3 lanes there.

There are even motorways (A28 near Amersfoort, and near Zwolle) which have over 120.000 AADT and are still 2x2 lanes. But there are also roads in the 180.000 - 200.000 area, which are only 2x3 lanes. Hence the traffic jams.

Under 70.000 is commonly seen as a quiet motorway here.
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Old July 30th, 2007, 05:53 PM   #913
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The netherland is far from being a common example.

As I've said, I think you will find very few rural interstates wich such amount of traffic.
Here in Portugal, Brise (main motorway owner) has to enlarge to 2x3 if the traffic is above 30000 and 2x4 if it's above 60000.
Anyway, as they don't administrate urban motorways, there are obviously many urban motorways which don't respect that.
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Old July 30th, 2007, 06:07 PM   #914
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Originally Posted by ZeTaCy View Post
But the real question here is, why aren't the authorities increasing the speed limit to 130 km/h (85mph?) everywhere?
$$$$ <--That's why.

If the speed limit is raised, a large portion of revenue is cut.
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Old August 2nd, 2007, 04:50 AM   #915
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Will all the defenders of the US interstate highway system please STFU now that a bridge carrying I-35 in DT Minneapolis just collapsed?
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Old August 2nd, 2007, 04:55 AM   #916
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The interstate highway system has nothing to do with the maintenance of one bridge. Each state has its way to maintenance the interstate infrastructure. A bridge fails doesn't mean the whole system is a failure
.
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Old August 2nd, 2007, 05:00 AM   #917
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Quote:
Originally Posted by ZeTaCy View Post
But the real question here is, why aren't the authorities increasing the speed limit to 130 km/h (85mph?) everywhere?
The speed limit is the safe travel speed at a normal road condition.
Raising speed limit to 85mph or 130 km/h is way too high for wet condition; plus highway design (at least for most part of the US) speed is around 85 - 90 mph. It is the limit of the highway design, travelling at that speed is actually in danger for the drivers, especially at curve sections.

Of course the drivers should slow down even slower than the speed limit if road condition and/or visibility is/are bad like during heavy rain storm and snow.
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Old August 2nd, 2007, 05:21 AM   #918
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Quote:
Originally Posted by EricIsHim View Post
The interstate highway system has nothing to do with the maintenance of one bridge. Each state has its way to maintenance the interstate infrastructure. A bridge fails doesn't mean the whole system is a failure
.
The burden of maintaining interstates has fallen to the states because the federal government has abrogated its duty to pay for the upkeep of the nation's roads.

The federal government has the resources to take care of the nation's road infrastructure, states have big problems coming up with the needed funds, which is why they push back and scale down road construction and improvement projects.
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Old August 2nd, 2007, 07:43 AM   #919
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Quote:
Originally Posted by hoosier View Post
Will all the defenders of the US interstate highway system please STFU now that a bridge carrying I-35 in DT Minneapolis just collapsed?
Well, being far from the defenders of the US interstate system, I should point out that the reasons for this failure are still unknown. The bridge might have collapsed because of the poor maintenance or because of the engineering fault during the construction or because something else.

I too am a proponent of the exclusively federal funding for all interstates, but in this case I would not jump to a quick conclusion that the bridge collapsed because the feds left it up to the states to maintain their portions of interstates. And of course, this bridge collapse alone could in no way be a proof of the entire interstate system failure.
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Old August 2nd, 2007, 08:51 AM   #920
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Will all the defenders of the US interstate highway system please STFU now that a bridge carrying I-35 in DT Minneapolis just collapsed?
I think the Interstate highway system is great. One cool thing I can say is that this same Interstate goes right through my town which is over 1000 miles away. One thing I really love about the Interstate system is that it takes you to the center of town. In other countries you usually have to take a city street top reach the center of town. Smart people who designed Interstates to reach the center of town.
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