Birdwatching From South Africa, joined Sep 2003, 3313 posts, RR: 54 Posted (1 year 2 months 3 weeks 1 day 22 hours ago) and read 3411 times:
Bit of a random topic, but after living for years in the US and in Germany, I have noticed how the on-ramps to highways (limited access 4-lane roads) are typically very different in both countries (there are exceptions in both directions)
Here's what I mean:
Typical US design, the ramps will go from both sides of the secondary road. This saves space, is easier to drive, I'd expect less accidents, and in many cases if the secondary street crosses over a bridge, you accelerate downhill to get to highway speed, and decelerate uphill. I LOVE this design.
In Germany, you'll typically find this design: Super tight curves that go down (or up) to the highway, you'll have to go really slow and then speed up like a madman. I'm sure these are much more dangerous for accidents, and they actually use MORE space than the super slim on ramps pictured above.
WHY, WHY, WHY?? Why would you, as an engineer, EVER use the curvy design when you could just as well use the other one? Don't tell me it's about the limited space in Europe, as the German design (in my opinion) uses more space than the other one.
Your opinions?
Soren
When I get sad, I stop being sad and be awesome instead! True story.
KiwiRob From New Zealand, joined Jun 2005, 3628 posts, RR: 2 Reply 1, posted (1 year 2 months 3 weeks 1 day 22 hours ago) and read 3407 times:
Quoting Birdwatching (Thread starter): Super tight curves that go down (or up) to the highway, you'll have to go really slow and then speed up like a madman.
Giving it some welly on those tight curves is fun and a challenge to get it just right.
MD11Engineer From Germany, joined Oct 2003, 12568 posts, RR: 68 Reply 3, posted (1 year 2 months 3 weeks 1 day 22 hours ago) and read 3375 times:
I think the main reason is that when you get off the Autobahn, the kurve forces you to slow down. Else there exists too much temptation to continue with Autobahn speed on the normal road (if you have ever driven for several hours at 120 + km/h, you´ll suddenly find normal roadspeeds like crawling.
In your example for the German intersection there are also houses where the second ramp of the American system would go.
In any case, if necessary you´ll have to slow down or stop at the BEGINNING of the acceleration lane to look for a suitable gap in the slow lane BEFORE accelerating to join the traffic on the Autobahn.
Klaus From Germany, joined Jul 2001, 20144 posts, RR: 57 Reply 4, posted (1 year 2 months 3 weeks 1 day 21 hours ago) and read 3322 times:
Quoting MD11Engineer (Reply 3): I think the main reason is that when you get off the Autobahn, the kurve forces you to slow down.
Only in one of the two directions. That's not it.
My guess would be that it can mean less construction effort: Only two slightly wider ramps will have to be built instead of four just slightly narrower ones.
And this form is a bit more flexible in tighter spaces when it can be put to either side, depending on circumstances.
We've got the other form as well, it's just not the only one.
PanHAM From Germany, joined May 2005, 6512 posts, RR: 25 Reply 5, posted (1 year 2 months 3 weeks 1 day 20 hours ago) and read 3302 times:
With a good driver education one can very easily manage both. As mentioned already, we got both types of highway access and depending on the local conditions. Germany is a bit smaller than the US and existed with build-up areas long before cars came and roads were needed.
Take the picture above, leaving in north western direction you have to enter the tight curve, entering in the same direction you can accelerate as you please. In the southern direction its the other way round.
Both exit and access offer enough slow down resp acceleration lanes, on Autobahns usually 300 meter. And it is really fun to drive the tight curves AND we have the cars t do it.
Quokka From , joined Dec 1969, posts, RR: Reply 7, posted (1 year 2 months 3 weeks 1 day 20 hours ago) and read 3284 times:
There are numerous forms of junctions in Germany and the layout takes into consideration a host of factors , including but not limited to, angle of the intersecting roads/ highways, types of roads that are at the intersection (an intersection of two stretches of Autobahn would be very different to that of an Autobahn and a relatively minor road),amount of space, built and natural environment, traffic densities and volumes, noise, site preparation, cost and other factors. No doubt such factors exist in the US as well and we also see various types of intersections there as well.
Charles79 From United States of America, joined Mar 2007, 1236 posts, RR: 5 Reply 9, posted (1 year 2 months 3 weeks 1 day 19 hours ago) and read 3226 times:
Quoting PanHAM (Reply 5): And it is really fun to drive the tight curves AND we have the cars t do it.
You are right about this statement...having visited Germany 7 times now I have thoroughly enjoyed BOTH driving on the Authobahn AND driving cars that actually drive and handle like...cars!
In response to the OP, it also has to do, I think, with the age of the system. The US Interstate network dates from the 50's, with some of the sections in western states being only 20 years old at most. The availability of space is also an issue, and again the layout you presented is more prevalent in southern and western states where space wasn't at a premium as in the Northeast. For instance, I lived in Connecticut for 5 years and in that state you find all types of on- and off-ramps, even left-lane exits! The style is more or less dictated by the availability of space (be it because of the terrain or existing development), funds, and who knows, maybe even local preferences.
In the end, though, any driver with proper training should be able to handle either situation. I have driven on both systems quite extensively and don't find either one particularly more challenging or worse to drive on than the other one.
rfields5421 From United States of America, joined Jul 2007, 4871 posts, RR: 21 Reply 10, posted (1 year 2 months 3 weeks 1 day 19 hours ago) and read 3207 times:
Quoting Charles79 (Reply 9): The US Interstate network dates from the 50's,
I think a lot of the 'challenging' on/off ramps are older ramps.
When the US Interstate system was first built - the IDEAL on/off ramp configuration was the cloverleaf with four 270 degree turns for on/ off ramps. The join lane on the main freeway was less than 100 yards long.
Over the years, the US has learned such ramps are not very safe, they are not supportive of good traffic flow and that the type ramp you show above is better. At a cost of 100s of billions of dollars, many older ramps have been demolished and replaced. That process is continuing today.
I suspect, but do not know, that many of the worst ramps in Germany were first built over 50 to 80 years ago. I would like to see a comparison of a completely new entrance/ exit ramp built in Germany in the past 10 years.
The US hasn't figured it out in many places. For one, many areas still lack long acceleration and merge lanes. Nothing like coming down a ramp (no matter what speed your at), and having dump straight in the freeway. Hope there's not a semi-truck there. Second, many areas have similar layouts to your German example, especially in major cities. The worst, IMO, is when it's a four clover-leaf style exit where the acceleration lane from the "On-Ramp" is the same lane as the deceleration lane for the "Off Ramp". You come up the on-ramp around the curve at 20-30 mph and have highway traffic flying along at 60-70 mph, little time to accelerate and get over because if you stay in the lane, you'll be right back on the off-ramp, and you have some of that traffic that's doing 60-70 mph trying to get in your lane so they can get off at the exit. I HATE the interstate highways in Ohio for both of these reasons.
sebolino From France, joined May 2001, 3611 posts, RR: 6 Reply 12, posted (1 year 2 months 3 weeks 1 day 18 hours ago) and read 3200 times:
The difference is obvious. In the "curvy" design you never cross a road, you just enter or exit the highway on your right and enters or exit the other road on the right. It's the most common used for highways in France.
In the first design, you have to enter a crossroad with redlights or stop signs when you get out of the highway, possibly at full speed. This is the design used for the peripheric highway around Paris. I 'm not sure it's safer, but for sure it needs less space.
PanHAM From Germany, joined May 2005, 6512 posts, RR: 25 Reply 13, posted (1 year 2 months 3 weeks 1 day 18 hours ago) and read 3193 times:
Quoting rfields5421 (Reply 10): suspect, but do not know, that many of the worst ramps in Germany were first built over 50 to 80 years ago. I would like to see a comparison of a completely new entrance/ exit ramp built in Germany in the past 10 years.
all of the very old on/off ramps in Germany have been rebuilt. You won't find a single one of the original Autrobahn ramps in the country. The last of the "tricky" ones i can remeber were some of the Aschaffenburg exits and the are all new now.
Super80DFW From United States of America, joined Oct 2007, 1595 posts, RR: 13 Reply 14, posted (1 year 2 months 3 weeks 1 day 18 hours ago) and read 3155 times:
Quoting Birdwatching (Thread starter): WHY, WHY, WHY?? Why would you, as an engineer, EVER use the curvy design when you could just as well use the other one?
I'm willing to bet the engineer drives a BMW equipped with some kind of sport suspension, so he probably loves the german on-ramps!
But really, in the german picture, on the SE corner of the intersection there appears to be a building of some sort very close to the corner. Possibly that has something to do with it in this instance, and maybe many more?
Right now there is an AA MD-80 flying over my house.
1337Delta764 From United States of America, joined Oct 2005, 5088 posts, RR: 2 Reply 16, posted (1 year 2 months 3 weeks 1 day 18 hours ago) and read 3146 times:
Of course, the ideal design is the multi-level stack interchange, as they can handle the most traffic and do not require signaling.
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ALTF4 From United States of America, joined Jul 2010, 988 posts, RR: 3 Reply 17, posted (1 year 2 months 3 weeks 1 day 16 hours ago) and read 3067 times:
They've been re-doing a lot of the ramps around here to be the cloverleaf style. I have mixed feelings, as others have said. The cloverleaf cuts down on congestion, as the traffic can continously flow onto the ramp without waiting at a light (the one pictured in the OP is only a half cloverleaf - real ones have another half on the other side of the secondary road). On the other hand, though, trying to merge soon enough to not get forced back off while not getting rammed by some idiot going 80mph in the exit lane... well... it can get messy.
That said, ramp metering makes a mess out of everything, though, because the meters are slow enough that a traffic light would not affect the ramp traffic. Also, metering traffic only 100 feet before the merge is a stupendously stupid idea, because you get up to 25 mph after flooring it, only to merge into 80 mph traffic.
The above post is my opinion. Don't like it? Don't read it.
Fly2HMO From , joined Dec 1969, posts, RR: Reply 18, posted (1 year 2 months 3 weeks 1 day 16 hours ago) and read 3059 times:
Quoting TheCommodore (Reply 2): compared to the USA, 12.3 deaths per 100.000 inhabitants.
That just goes to show that 99% of my fellow countrymen just don't know how to drive.
Many freeways and interstates are just as good if not better than the autobahn, yet people still manage to kill themselves. It would help if getting your license in the US took more than just having a heartbeat and the capability to breathe.
ALTF4 From United States of America, joined Jul 2010, 988 posts, RR: 3 Reply 19, posted (1 year 2 months 3 weeks 1 day 16 hours ago) and read 3043 times:
Quoting Fly2HMO (Reply 18): It would help if getting your license in the US took more than just having a heartbeat and the capability to breathe.
Hey now, I had to be able to turn this thing called a "steeling wheel" or a "steering wheel" or something like that. At any rate, the lady told me it "makes the car go where you want it to go".
I had to unhitch my house from the back of my car, though, before I could take the test.
/s
The above post is my opinion. Don't like it? Don't read it.
moose135 From United States of America, joined Oct 2004, 1834 posts, RR: 14 Reply 20, posted (1 year 2 months 3 weeks 1 day 16 hours ago) and read 3032 times:
Quoting PanHAM (Reply 13): all of the very old on/off ramps in Germany have been rebuilt. You won't find a single one of the original Autrobahn ramps in the country.
I believe the 8th Air Force helped with that effort in the mid-1940s.
aero145 From Iceland, joined Jan 2005, 3045 posts, RR: 27 Reply 22, posted (1 year 2 months 3 weeks 1 day 15 hours ago) and read 2976 times:
I can and can not understand your rant.
Of course it’s not comfortable to have to “accelerate like a mad man” while driving onto the Autobahn, but I cannot understand why you don’t mention the very common cloverleaf interchanges. This one is maybe not a real cloverleaf interchange, but it’s annoying enough to drive KA-Damm into the east and onto the A565 into the north or A565 into the north onto KA-Damm into the west.
courtesy of Maps.Google.de
When coming off A565, I sometimes have to put the pedal to the metal to go past accelerating cars on the right lane, and sometimes I have to brake heftily after accelerating a bit while entering the Autobahn because of people coming off the Autobahn that drive with 100 km/h.
The cloverleafs are IMO the only intersections that shouldn’t exist, because of the collision hazard. The others may be annoying, but not as dangerous.
To date I haven’t had any real problems with the cloverleafs, but I’ve been in a car where the driver didn’t really understand the concept and we were only lucky that the other driver had a quick reflex, otherwise we would have been pretty screwed.
travelin man From United States of America, joined Mar 2000, 3262 posts, RR: 0 Reply 23, posted (1 year 2 months 3 weeks 1 day 15 hours ago) and read 2956 times:
The US probably has as many variations in interchanges as Germany does. Heck, just in Los Angeles you have:
Cloverleaf:
Albeit not including the crossing of the traffic flows like in my example, yours only has a loop while driving onto the freeway, not driving off it – I could live with those.
chrisair From United States of America, joined Sep 2000, 1461 posts, RR: 4 Reply 26, posted (1 year 2 months 3 weeks 1 day 14 hours ago) and read 3087 times:
Quoting travelin man (Reply 23): Heck, just in Los Angeles you have:
Cloverleaf:
N1120A From United States of America, joined Dec 2003, 25729 posts, RR: 86 Reply 28, posted (1 year 2 months 3 weeks 1 day 13 hours ago) and read 3083 times:
Quoting Birdwatching (Thread starter): and in many cases if the secondary street crosses over a bridge, you accelerate downhill to get to highway speed, and decelerate uphill.
There is plenty of the opposite too.
Quoting Charles79 (Reply 9): The US Interstate network dates from the 50's, with some of the sections in western states being only 20 years old at most
The German network is older, but they actually spend money on infrastructure there.
Quoting ALTF4 (Reply 17): Also, metering traffic only 100 feet before the merge is a stupendously stupid idea, because you get up to 25 mph after flooring it, only to merge into 80 mph traffic.
The point of metering is that you do it at times where the traffic isn't going fast, in order to control congestion.
Mangeons les French fries, mais surtout pratiquons avec fierte le French kiss
Glom From United Kingdom, joined Apr 2005, 2793 posts, RR: 11 Reply 29, posted (1 year 2 months 3 weeks 1 day 12 hours ago) and read 3003 times:
Quoting ALTF4 (Reply 17): They've been re-doing a lot of the ramps around here to be the cloverleaf style.
They're putting in cloverleaf interchanges? I thought they were supposed to be taking them out because of the horrendous weaving problems they cause. At least partially unroll it, like at the interchange of the M40 and M25.
travelin man From United States of America, joined Mar 2000, 3262 posts, RR: 0 Reply 31, posted (1 year 2 months 3 weeks 1 day 8 hours ago) and read 2864 times:
Quoting Glom (Reply 29): They're putting in cloverleaf interchanges? I thought they were supposed to be taking them out because of the horrendous weaving problems they cause.
Here in SoCal they've been taking OUT the cloverleaf freeway interchanges.
The 60/215/91 interchange used to be a traditional full cloverleaf, but they rebuilt it a year or two ago and replaced two of the cloverleafs with flyovers:
The 5/55 interchange was also completely rebuilt from a traditional cloverleaf (you can still kind of see where the old cloverleafs used to be):
Cloverleafs are really not a good design for interchanges of two freeways with high speed lane changes.
dfwrevolution From United States of America, joined Jan 2010, 755 posts, RR: 54 Reply 33, posted (1 year 2 months 3 weeks 1 day 4 hours ago) and read 2744 times:
Quoting TheCommodore (Reply 2): Not sure about which is safer, German or US. Check out the accident rate between both countries, per capita of Pop.
Germany, 4.5 deaths per 100,000 inhabitants, compared to the USA, 12.3 deaths per 100.000 inhabitants.
Deaths per inhabitant is a just about meaningless if the population of one country drives significantly more than the other. Normalize for kilometers driven, and Germany suffers 7.2 fatalities billion km versus 8.5 per billion km in the USA. That's a whopping 18% difference rather than the 270% you tried to portray. These are numbers from your own source.
Lots of factors could easily account for an 18% difference that have nothing to do with engineering competence or driver skill. For example, rural undivided roads in any country are going to be less safe than divided controlled access freeways. If Americans drive more miles on rural roads, that will slant the statistics against the US. Only 12% of Germany's population lives in rural areas compared to 20% of Americans. Seems like that is probably a safe assumption.
Even the faulty per capita numbers you provided are determined by averaging fatalities over millions of people. It would make no sense to use such an average to conclude that any given highway design in Germany is safter than any given highway design in the U.S. You could basically find an untrafficed intersection in Germany and leave the traffic lights green in all directions without even budging the fatalities per capita for Germany. Would you take a snapshot of that intersection and hold it as safer than a U.S. intersection because of the per capita fatality statistic is lower for Germany?
Quoting Birdwatching (Thread starter): Typical US design, the ramps will go from both sides of the secondary road. This saves space, is easier to drive, I'd expect less accidents, and in many cases if the secondary street crosses over a bridge, you accelerate downhill to get to highway speed, and decelerate uphill. I LOVE this design.
I happen to agree 100%. While this design is common in the U.S., it is not universal. The interstate highways in New York happen to use the "German" style on/off-ramps. I they make it considerably easier to enter the wrong direction of traffic, especially if you are unfamiliar with the particular intersection. They also make it more difficult to access road-side services like gas stations, restaurants, shops, or hotels.
mham001 From United States of America, joined Feb 2005, 2557 posts, RR: 3 Reply 34, posted (1 year 2 months 3 weeks 1 day 4 hours ago) and read 2746 times:
Quoting Fly2HMO (Reply 18): That just goes to show that 99% of my fellow countrymen just don't know how to drive.
It might be more accurate to compare deaths with miles driven. I read today Americans drove 3 trillion miles last year.
California is phasing out cloverleafs. They have mostly settled on the frontage road style or whatever its called. It uses less space overall. I like cloverleafs, in some places its the only chance you get to go around a curve. its nice for making highway u-turns too without stopping.
dfwrevolution From United States of America, joined Jan 2010, 755 posts, RR: 54 Reply 35, posted (1 year 2 months 3 weeks 1 day 4 hours ago) and read 2731 times:
Quoting N1120A (Reply 28): The German network is older, but they actually spend money on infrastructure there.
And the $300 billion we spend per year is chopped liver?
N1120A From United States of America, joined Dec 2003, 25729 posts, RR: 86 Reply 36, posted (1 year 2 months 3 weeks 1 day 3 hours ago) and read 2693 times:
Quoting dfwrevolution (Reply 33):
Deaths per inhabitant is a just about meaningless if the population of one country drives significantly more than the other. Normalize for kilometers driven, and Germany suffers 7.2 fatalities billion km versus 8.5 per billion km in the USA. That's a whopping 18% difference rather than the 270% you tried to portray. These are numbers from your own source.
Meanwhile, the US has ridiculously low speed limits on its highways, while Germany has vast portions that are unlimited and still more that are 130 km/h. The only US highways that come close are the 80 mph/128 km/h portions of Interstates 10 and 20 in extremely sparsely populated portions of Texas.
Quoting dfwrevolution (Reply 35):
And the $300 billion we spend per year is chopped liver?
Except, of course, that you claim we spend nearly twice than we actually do. If we spent $300 million a year, we might actually get things done.
dfwrevolution From United States of America, joined Jan 2010, 755 posts, RR: 54 Reply 37, posted (1 year 2 months 3 weeks 18 hours ago) and read 2556 times:
Quoting N1120A (Reply 36): Except, of course, that you claim we spend nearly twice than we actually do. If we spent $300 million a year, we might actually get things done.
The $146 billion in your source is just for highways. We spend money on lots of other types of infrastructure, too.
Quoting N1120A (Reply 36): Meanwhile, the US has ridiculously low speed limits on its highways, while Germany has vast portions that are unlimited and still more that are 130 km/h. The only US highways that come close are the 80 mph/128 km/h portions of Interstates 10 and 20 in extremely sparsely populated portions of Texas.
We've already established that controlled access highways are safer than uncontrolled roads, which due to the demographics of the U.S., more Americans drive on than Germans.
MD11Engineer From Germany, joined Oct 2003, 12568 posts, RR: 68 Reply 38, posted (1 year 2 months 3 weeks 17 hours ago) and read 2544 times:
Quoting dfwrevolution (Reply 37): We've already established that controlled access highways are safer than uncontrolled roads, which due to the demographics of the U.S., more Americans drive on than Germans.
You haven´t been to Germany lately? We have a lot of rural regions without Autobahn acccess. I drive 25 km to work and back every day on such roads (called Landstrasse in German). Most of them have only one lane in each direction. Maximum speed is 100 km/h.
Depending on where they are, they are often curvy (especially in the hills and mountains) and bordered by ditches and trees.
Jan
1337Delta764 From United States of America, joined Oct 2005, 5088 posts, RR: 2 Reply 39, posted (1 year 2 months 3 weeks 15 hours ago) and read 2458 times:
Quoting Glom (Reply 29): They're putting in cloverleaf interchanges? I thought they were supposed to be taking them out because of the horrendous weaving problems they cause. At least partially unroll it, like at the interchange of the M40 and M25.
My guess is that they are actually putting in stack interchanges, not cloverleafs. I have met some people who think the Big I (I-25/I-40 interchange) in Albuquerque is a cloverleaf, when in truth it is a 5-level stack interchange.
The Pink Delta 767-400ER - The most beautiful aircraft in the sky
aa757first From United States of America, joined Aug 2003, 3289 posts, RR: 10 Reply 40, posted (1 year 2 months 3 weeks 14 hours ago) and read 2445 times:
Quoting ALTF4 (Reply 17): That said, ramp metering makes a mess out of everything, though, because the meters are slow enough that a traffic light would not affect the ramp traffic. Also, metering traffic only 100 feet before the merge is a stupendously stupid idea, because you get up to 25 mph after flooring it, only to merge into 80 mph traffic.
80 MPH traffic? I wish. When highways go on meter here in Northern California, traffic is going 35 MPH on a good day.
Quoting Fly2HMO (Reply 18): That just goes to show that 99% of my fellow countrymen just don't know how to drive.
Many freeways and interstates are just as good if not better than the autobahn, yet people still manage to kill themselves. It would help if getting your license in the US took more than just having a heartbeat and the capability to breathe.
I was surprised when riding on the Autobahn. I thought California's highways were far safer and better designed. I'd much rather be going 110 MPH on the I-880 (I don't) than 110 MPH on the segments of the Autobahn I was on.
But, like you said, Americans can't drive. Its not our fault, really, since our license tests are a joke. In PA, you have to answer 15 out of 18 multiple choice questions on a computer, complete 50 hours of driving with a parent and then take your driver's test. I had to put on my hazard lights, honk my horn, parallel park and drive around the block. One driving license center would just make kids drive around the parking lot if it was raining because they didn't want them out on the road.
Kind of scary to look back on the way I drove when I was 16...and I was one of the better drivers I knew.
rfields5421 From United States of America, joined Jul 2007, 4871 posts, RR: 21 Reply 41, posted (1 year 2 months 3 weeks 14 hours ago) and read 2430 times:
One question about the original post - the German example looks to me like many in the US which were built for Toll Roads - with space to allow vehicles stopping to make payment at a toll booth for both entrance and exit to not back up traffic into the regular regular road and high speed roadway.
I've seen quite a few in the US like that, though they are disappearing as more and more roads go to No Stop electronic tag charges and license plate billing.
Garpd From UK - Scotland, joined Aug 2005, 2103 posts, RR: 4 Reply 42, posted (1 year 2 months 3 weeks 14 hours ago) and read 2412 times:
All these junctions seem perfecty safe and easy to me.
Right in my area there is one of the most ill thought out on and off ramp I have ever come across.
Traffic wanting to use the off ramp (orange arrow) have to dodge people crawling onto the motorway from beside and being them (Red Arrow). The section the red arrow is on is a steep climb and folks rarely get up to speed before joining the motorway. It has caused many an accident as slow drivers pull out into fast moving traffic. Or someone who is fast on the On ramp pulls up alongside to a vehicle merging off and BANG.
Now, it strikes me as logical that on OFF ramp should always come before an ON ramp!
Only 300 yards up the same road is the tightest on ramp you'll ever see!
It's a down hill, sharp right hand bend which prone to getting covered in slippy morning dew or icing in winter. It is followed by a sharpish left turn to align with the motorway. The quick direction change has caused many vehicles to spin out there as the g-forces are unloaded and loaded quickly. Consequently many drivers crawl along and do not get up to speed, thus causing motorway traffic to break.
Quoting MD11Engineer (Reply 3): (if you have ever driven for several hours at 120 + km/h, you´ll suddenly find normal roadspeeds like crawling.
There is one Autobahn exit I regularly take which does not have a curve, but goes straight for one or two kilometers. The speed limit goes down to 70 km/h and then to 50 km/h. I really need to watch the speed-indicator more closely then since my perception of speed has definitely changed. It gets back to normal I'm forced to slow down before a curve, though... so they serve a purpose, whether intended or not.
Et là tu montes encore plus haut et ça persiste, alors on vole
Aesma From France, joined Nov 2009, 3001 posts, RR: 3 Reply 44, posted (1 year 2 months 3 weeks 12 hours ago) and read 2347 times:
The comparison in the first post is flawed as one is an intersection between a freeway and a town street, it seems. You can get this in France too, and my guess is Germany has the same. Out of the highway/freeway, you get a stoplight. In the cloverleaf design, you don't have to stop, however it may need more merging skills, which is something we learn for our driver's license (mandatory 20h training, and an exam roughly half takers have to pass several times, with more training).
What is really better than this is the stacked system, but that is far more expensive to build (and probably maintain). BTW, is it reasonable to build those in earthquake prone California ?
Quoting Garpd (Reply 42): Traffic wanting to use the off ramp (orange arrow) have to dodge people crawling onto the motorway from beside and being them (Red Arrow). The section the red arrow is on is a steep climb and folks rarely get up to speed before joining the motorway. It has caused many an accident as slow drivers pull out into fast moving traffic. Or someone who is fast on the On ramp pulls up alongside to a vehicle merging off and BANG.
Now, it strikes me as logical that on OFF ramp should always come before an ON ramp!
There is the same stuff near where I live, and I take it very infrequently when coming back from vacation, several times I didn't understand what was going on until it was too late and I didn't exit as I should have. It's downhill however so the major problem is exiting while people merging are already at full speed.
Quoting Luftfahrer (Reply 43): There is one Autobahn exit I regularly take which does not have a curve, but goes straight for one or two kilometers. The speed limit goes down to 70 km/h and then to 50 km/h. I really need to watch the speed-indicator more closely then since my perception of speed has definitely changed. It gets back to normal I'm forced to slow down before a curve, though... so they serve a purpose, whether intended or not.
There is this in miniature in my town, with a 110Km/h national road exiting in a straight line for quite an unusual distance, before an almost 90° turn. I would usually continue almost at full speed, coasting until the last moment, until I once saw cops there, stopping people doing like me...
New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
BMI727 From United States of America, joined Feb 2009, 11547 posts, RR: 27 Reply 46, posted (1 year 2 months 3 weeks 5 hours ago) and read 2235 times:
Quoting travelin man (Reply 31): Here in SoCal they've been taking OUT the cloverleaf freeway interchanges.
That seems to be the trend around the country. Cloverleafs are pretty space efficient, but the situation where traffic coming in must merge left and traffic leaving must merge right within a short space of a couple hundred feet can slow traffic down at best and be dangerous at worst.
Quoting N1120A (Reply 36): Meanwhile, the US has ridiculously low speed limits on its highways
That gets really annoying.
But here is my rant: Why can't the US put in more roundabouts? It doesn't take much space, it's efficient since cars don't have to stop in lighter traffic, and there is far less need to be jockeying to get into the correct lane to get where you are going. Of course, when encountering one of the few roundabouts there are here, most American drivers don't seem to have a clue of what to do.
Why do Aerospace Engineering students have to turn things in on time?
photopilot From Cuba, joined Jul 2002, 2418 posts, RR: 22 Reply 49, posted (1 year 2 months 2 weeks 6 days 20 hours ago) and read 2117 times:
Quoting Birdwatching (Thread starter): WHY, WHY, WHY?? Why would you, as an engineer, EVER use the curvy design when you could just as well use the other one?
Because European cars are designed with HANDLING and CONTROL in mind while the typical USA car is designed to go like stink in a straight line, but handles like sh*t.
Quoting PanHAM (Reply 5): And it is really fun to drive the tight curves AND we have the cars t do it.
Garpd From UK - Scotland, joined Aug 2005, 2103 posts, RR: 4 Reply 50, posted (1 year 2 months 2 weeks 6 days 20 hours ago) and read 2108 times:
Quoting photopilot (Reply 49): Because European cars are designed with HANDLING and CONTROL in mind while the typical USA car is designed to go like stink in a straight line, but handles like sh*t.
ALTF4 From United States of America, joined Jul 2010, 988 posts, RR: 3 Reply 51, posted (1 year 2 months 2 weeks 5 days 17 hours ago) and read 1886 times:
Quoting aa757first (Reply 40): 80 MPH traffic? I wish. When highways go on meter here in Northern California, traffic is going 35 MPH on a good day.
Quoting N1120A (Reply 28): The point of metering is that you do it at times where the traffic isn't going fast, in order to control congestion.
Feel free to try to gently let my local DOT know how metering is supposed to work. I have tried. They turn metering on when there is speed limit traffic (well, 55mph speed limit in the city, but people go 75+ all the time) and I have yet to see the meters running during rush hour on the ramp I use the most.
Quoting Glom (Reply 29): They're putting in cloverleaf interchanges?
Yep - in order to cut down on the problems with left-turn lanes and arrows and congestion for entering the freeway.
The above post is my opinion. Don't like it? Don't read it.
sebolino From France, joined May 2001, 3611 posts, RR: 6 Reply 52, posted (1 year 2 months 2 weeks 5 days 16 hours ago) and read 1837 times:
Actually, the most disturbing in Germany, is that the sign which tells you were to exit the highway is at the end of the desceleration way and not at the start. Very dangerous in my opinion.
Slider From United States of America, joined Feb 2004, 6219 posts, RR: 42 Reply 53, posted (1 year 2 months 2 weeks 5 days 14 hours ago) and read 1776 times:
Quoting TheCommodore (Reply 2): Check out the accident rate between both countries, per capita of Pop
dfwrevolution already answered this quite appropriately, but to elaborate, I don't think comparisons are fully valid.
Quoting rfields5421 (Reply 10): Over the years, the US has learned such ramps are not very safe, they are not supportive of good traffic flow and that the type ramp you show above is better. At a cost of 100s of billions of dollars, many older ramps have been demolished and replaced. That process is continuing today.
Not to mention that from a cost standpoint, it's far easier and more expeditious to have a straight exit than a curved one, generally speaking.
Quoting 1337Delta764 (Reply 16): Of course, the ideal design is the multi-level stack interchange, as they can handle the most traffic and do not require signaling.
They are, however, the most costly...any time you elevate concrete for the large overpasses, the cost climbs significantly. So in the States, as I'm sure in many places, engineers have to balance cost to volume when designing and constructing.
Glom From United Kingdom, joined Apr 2005, 2793 posts, RR: 11 Reply 54, posted (1 year 2 months 2 weeks 5 days 14 hours ago) and read 1771 times:
Quoting BMI727 (Reply 46): But here is my rant: Why can't the US put in more roundabouts? It doesn't take much space, it's efficient since cars don't have to stop in lighter traffic, and there is far less need to be jockeying to get into the correct lane to get where you are going. Of course, when encountering one of the few roundabouts there are here, most American drivers don't seem to have a clue of what to do.
Where though? Since this topic is about highways, the subject roads are grade separated, meaning no roundabouts, lights or stop signs. Unless you mean more roundabout interchanges. But while roundabout interchanges work very well and better than diamonds generally, I would not bemoan the abundance of high quality free flowing interchanges you have over there.
PHLBOS From United States of America, joined Mar 2004, 6974 posts, RR: 31 Reply 55, posted (1 year 2 months 2 weeks 5 days 13 hours ago) and read 1753 times:
Quoting BMI727 (Reply 46): Why can't the US put in more roundabouts? It doesn't take much space, it's efficient since cars don't have to stop in lighter traffic, and there is far less need to be jockeying to get into the correct lane to get where you are going.
In Massachusetts, they're called rotaries and they usually work fairly well. Although the one along Route 128 just east of the Anniquam River Bridge crossing in Gloucester can catch a few motorists off-guard. The northbound lanes have some lengthy skidmarks at the approach end of the rotary.
In New Jersey they were called traffic circles and have been, by and large, phased out over the last decade or two. There are still a handful remaining though; US 30/130 in Collingswood and the Route 70/73 in Marlton, the latter is being replaced with an highway-type interchange. The reasons why traffic circles had issues in NJ were:
1. The rules for entry were the exact opposite of what Massachusetts had for its rotaries. In NJ, the traffic entering the circle had the right-of-way; whereas in MA, the traffic IN the rotary had the right-of-way.
2. The turning radius of the NJ circles were typically smaller than those of MA rotaries; which became an issue for roadways that had higher traffic volumes. Such conditions warranted the erection of traffic signals at each circle entry point.
3. The scenario described in #2 would cause traffic to back up on the mainline roadways.
Quoting BMI727 (Reply 46): Of course, when encountering one of the few roundabouts there are here, most American drivers don't seem to have a clue of what to do.
Different states having conflicting rules regarding which vehicles have the right-of-way at a traffic circle/rotary doesn't exactly help either.
From my experience (born in and learned how to drive in the Greater Boston area), the Massachusetts rule (where the INSIDE traffic has the right-of-way) seems to work better.
Quoting N1120A (Reply 28): Quoting ALTF4 (Reply 17):
Also, metering traffic only 100 feet before the merge is a stupendously stupid idea, because you get up to 25 mph after flooring it, only to merge into 80 mph traffic.
The point of metering is that you do it at times where the traffic isn't going fast, in order to control congestion.
The ones along US 22 in ABE area and the ones along I-476 (west of Philly, for the 1st 20 miles) in PA are only turned on during rush hours.
Quoting ALTF4 (Reply 51): Feel free to try to gently let my local DOT know how metering is supposed to work. I have tried. They turn metering on when there is speed limit traffic (well, 55mph speed limit in the city, but people go 75 all the time) and I have yet to see the meters running during rush hour on the ramp I use the most.
What state do you reside in that does that?
Quoting rfields5421 (Reply 41): One question about the original post - the German example looks to me like many in the US which were built for Toll Roads - with space to allow vehicles stopping to make payment at a toll booth for both entrance and exit to not back up traffic into the regular regular road and high speed roadway.
On the contrary, that diamond-type interchange is a lot more common along freeways than tollways. Many toll road interchanges in the eastern U.S. (particularly ones that involve taking a toll ticket upon entry and paying when leaving or getting EZ-Pass scans - MA, NJ, OH, PA Turnpikes and NY Thurways as prime examples) consist of 2 trumpet-ramp style interchanges linked with a connector road that has the toll/EZ-Pass plaza situated in-between. This type of design requires a lot more land.
The only time I've seen toll booths on a diamond-type interchange are along tolls roads involving the majority of tolls being taken/collected along plazas located along the mainline highway; the Garden State Parkway and the Atlantic City Expressway in NJ are examples of these.
Quoting rfields5421 (Reply 41): I've seen quite a few in the US like that, though they are disappearing as more and more roads go to No Stop electronic tag charges and license plate billing.
Guess again, along the upper-end of the PA Turnpike's Northeast Extension (I-476); some of the newer interchanges between mainline plazas have this type of toll booth/ramp arrangement (w/one of them being an EZ-Pass lane).
Quoting BMI727 (Reply 46): Cloverleafs are pretty space efficient, but the situation where traffic coming in must merge left and traffic leaving must merge right within a short space of a couple hundred feet can slow traffic down at best and be dangerous at worst.
Having separate frontage/collector-distributor lanes can help alleviate that somewhat.
Quoting N1120A (Reply 36): The only US highways that come close are the 80 mph/128 km/h portions of Interstates 10 and 20 in extremely sparsely populated portions of Texas.
Doesn't Montana have some posted 80 mph daytime speed limit stretches along their Interstates as well? They used to have un-numbered daytime speeds which had signs that read Reasonable and Prudent from 1995 through 1998(?).
Quoting mham001 (Reply 34): They have mostly settled on the frontage road style or whatever its called. It uses less space overall. I like cloverleafs, in some places its the only chance you get to go around a curve. its nice for making highway u-turns too without stopping.
See above, they're usually referred to as collector-distributor roads. The nearest example of such where I live is the I-95/Route 420 interchange in Essington, PA (near PHL).
Quoting Slider (Reply 53): Quoting 1337Delta764 (Reply 16):
Of course, the ideal design is the multi-level stack interchange, as they can handle the most traffic and do not require signaling.
They are, however, the most costly...any time you elevate concrete for the large overpasses, the cost climbs significantly. So in the States, as I'm sure in many places, engineers have to balance cost to volume when designing and constructing.
Not to mention the additional land-takings. That said, I'm still waiting for the long-promised fly-over ramps being proposed for the congested I-93/I-95 (Route 128) cloverleaf interchange in Woburn, MA.
"TransEastern! You'll feel like you've never left the ground because we treat you like dirt!" SNL Parady ad circa 1981
MD11Engineer From Germany, joined Oct 2003, 12568 posts, RR: 68 Reply 56, posted (1 year 2 months 2 weeks 5 days 13 hours ago) and read 1731 times:
Quoting sebolino (Reply 52): Actually, the most disturbing in Germany, is that the sign which tells you were to exit the highway is at the end of the desceleration way and not at the start. Very dangerous in my opinion.
The sign marks the point from which on normal road rules apply (e.g. slower traffic by cyclists and pedestrians, speed limit of 100 km/h (outside urban areas) or 50 km/h (inside urban areas)). You should have slowed down to this speed by the time you reach the sign, in most cases there are speed limit signs on the decelaration lane.
DiamondFlyer From United States of America, joined Oct 2008, 1107 posts, RR: 3 Reply 57, posted (1 year 2 months 2 weeks 5 days 13 hours ago) and read 1726 times:
Quoting BMI727 (Reply 46): But here is my rant: Why can't the US put in more roundabouts? It doesn't take much space, it's efficient since cars don't have to stop in lighter traffic, and there is far less need to be jockeying to get into the correct lane to get where you are going. Of course, when encountering one of the few roundabouts there are here, most American drivers don't seem to have a clue of what to do.
For the same reason we have really low speed limits. We give a drivers license to anyone with a pulse and the ability to turn the key. Personally, I've seen some roundabouts put in, in locations that shall we say, aren't in urban areas. People don't know what the heck to do with the thing.
MD11Engineer From Germany, joined Oct 2003, 12568 posts, RR: 68 Reply 58, posted (1 year 2 months 2 weeks 5 days 13 hours ago) and read 1722 times:
Quoting sebolino (Reply 52): Actually, the most disturbing in Germany, is that the sign which tells you were to exit the highway is at the end of the desceleration way and not at the start. Very dangerous in my opinion.
The sign marks the point from which on normal road rules apply (e.g. slower traffic by cyclists and pedestrians, speed limit of 100 km/h (outside urban areas) or 50 km/h (inside urban areas)). You should have slowed down to this speed by the time you reach the sign, in most cases there are speed limit signs on the decelaration lane.
aloges From Germany, joined Jan 2006, 7588 posts, RR: 51 Reply 59, posted (1 year 2 months 2 weeks 5 days 13 hours ago) and read 1722 times:
Quoting sebolino (Reply 52): Actually, the most disturbing in Germany, is that the sign which tells you were to exit the highway is at the end of the desceleration way and not at the start. Very dangerous in my opinion.
I guess you're thinking of the "Ausfahrt" sign. While that is indeed right where you'd crash into the guardrail if you kept going in a straight line, we do have signs announcing the exit: usually a big one 1 km before the exit, then a smaller one at 500 m and three even smaller ones at 300, 200 and 100 m - which you'll see anyway since you're in the right lane by that time if you do want to exit the Autobahn.
Walk together, talk together all ye peoples of the earth. Then, and only then, shall ye have peace.
sprout5199 From United States of America, joined Feb 2005, 1673 posts, RR: 2 Reply 60, posted (1 year 2 months 2 weeks 5 days 12 hours ago) and read 1687 times:
Quoting Garpd (Reply 42): Right in my area there is one of the most ill thought out on and off ramp I have ever come across.
I can see, as everyone is driving on the wrong side of the road.
rfields5421 From United States of America, joined Jul 2007, 4871 posts, RR: 21 Reply 61, posted (1 year 2 months 2 weeks 5 days 11 hours ago) and read 1667 times:
We used to have several of those 'consolidated' toll exchanges along what is now I-30 between Dallas and Fort Worth - which was originally built as a toll road opening in 1957. After 1977 it was no longer a toll road and all but one of those type interchanges has been demolished and replaced with the diamond type exit.
There were a few others scattered around the state which are now gone.
I've also seen them in Oklahoma, and a few which were the straight through diamond type. The newer builds appear to be the straight through type.
Last October the wife and I were visiting her son in Fort Lauderdale where they have several of the consolidated exchanges and they told us that the plans are to demolish those in favor of the straight in/ out diamond exchanges.
Consolidating the entry and exit traffic from four separate routes to one or two routes saves a lot of money on the cost of toll booth operations - but with the trend toward toll tags and direct billing based on license plate ID - I would expect it to be cheaper to do the diamond type exchange.
There was a lot of debate about the people who use toll tags having to subsidize the people without them who ignore the bills for the toll roads here in Texas. I guess in states where the toll enforcement has been very high, that might be a bigger issue.
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