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Dutch Engineer posted:The bypass is built higher than the roundabout. If a car would enter it, the height difference would cause damage to the underside of the car. Trucks can easily clear the difference because they have a larger ground clearance. They did something like this in a nearby village here. They built a roundabout near an industrial facility under construction, which required large parts to be transported. At first they just built the entire center of the roundabout like that. as raised concrete, so that the construction trucks could drive over it. After construction was done, they filled in the center. Hope they don't need replacement parts!
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Mar 23, 2012 14:44
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You can see it pretty clearly on street view: http://maps.google.nl/?ll=52.127842...,74.28,,0,15.92 It looks to me like cars could use it, but it's essentially driving up on to the sidewalk so you couldn't do it at speed.
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Mar 23, 2012 15:52
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Oh hey, remember speedbump chat? Well, now there's a very literal speedtrap. A swedish company called Edeva is developing this thing called Actibump which is basically a trapdoor in the road that will make you hit a 6cm tall steel lip if you're speeding.  Can't really see this being a good idea.
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Mar 23, 2012 15:55
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smackfu posted:You can see it pretty clearly on street view: I haven't been there in years, in my memory the barrier used to be higher. Now that I see it again, I see the bypass connects an eastbound lane with a westbound lane. Perhaps that's a good enough deterrent for regular cars. Then again, it would probably deter logging trucks too. Looks like it's only usable for special transport when the road is closed off for regular traffic.
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Mar 23, 2012 15:58
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MrBling posted:Oh hey, remember speedbump chat? Well, now there's a very literal speedtrap. I don't even see how that could be legal. A device that's actively designed to cause a curb impact? I wonder who'll die first. E: I'm pretty sure that installing those would fall under the various anti-booby trapping laws, at least in the US.
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Mar 23, 2012 16:04
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gently caress, I hate to think of an ambulance racing to the hospital going over that. And, isn't this the thread where I read about a police officer dying from a snapped neck speeding over a speed bump? I know this isn't as high as those but, yeah, seems like not a great idea maybe.
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Mar 23, 2012 16:06
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MrBling posted:Oh hey, remember speedbump chat? Well, now there's a very literal speedtrap. I've always thought speedbumps that somehow only activated if you were actually going at above the desired speed were a good idea - especially given that I live in a neighbourhood with particularly annoying ones even if you're going under 20mph (and ones, thankfully mainly gone now, that would scrape the bottom of your car and gently caress up your wheel alignment if you do them at more than 5mph.) Assuming the impact caused by these is no worse than your average speed bump, what's the problem?
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Mar 23, 2012 16:09
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A 6cm right-angle steel lip is more than enough to blow out a tire and dent a steel rim at speed. Plus it comes with the same alignment-loving properties as a pothole. There's a reason speed bumps are graded.
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Mar 23, 2012 17:06
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thelightguy posted:A 6cm right-angle steel lip is more than enough to blow out a tire and dent a steel rim at speed. Would it maybe be possible to do an "inverted speedbump" which uses this system but makes the down and up bits more gradual?
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Mar 23, 2012 17:15
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A friend of mine once watched a fully laden fire truck blow it's rear axle by going over a ridiculous speedbump at ~50 mph. Apparently if you've got a big tank full of water sloshing around in the back you shouldn't do that.
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Mar 23, 2012 17:36
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TELL ME ABOUT: Round about design. How large should they be? How many roads can connect to them? Most seem to be simple 4-way intersections, but what about having 6 roads or 8 roads coming into a traffic circle. Do more roads just add to the diameter? What other factors must be taken into account?
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Mar 23, 2012 18:18
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Baronjutter posted:TELL ME about : Ideally, you want 12 entrances 
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Mar 23, 2012 20:52
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Mandalay posted:Ideally, you want 12 entrances
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Mar 23, 2012 21:07
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They put a roundabout in a nearby city that works pretty good.  http://binged.it/GNaoBX It has slip roads so traffic turning right can avoid the roundabout entirely. There's a lot of logging in the area, so double-trailer trucks have to negotiate this intersection. Google still has old satellite imagery, so you can still see the "before" picture here: http://g.co/maps/tsnaa It used to be a triangular T intersection where the lanes crossed each other at odd angles. The south and west legs are the main highway in the region, so there were always cars waiting to turn left. Question: why do the northbound legs swerve right before the roundabout? Wouldn't it make sense for them to just be straight like the exit lanes?
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Mar 23, 2012 21:28
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Baronjutter posted:TELL ME about : The size depends on the largest vehicle using it. 100 feet outer diameter (30m) is a pretty good baseline. You ideally want four roads at right angles, or fewer, but I've seen roundabouts with seven. More roads mean a bigger footprint, more conflicts, and more accidents. It also means you'll have higher speeds, because of your larger circle. There are plenty of other factors! You want a low grade (<2%) on the circular roadway, relatively low (<4%) on the approaches, illumination, good visibility to the central island, landscaping that restricts how much an entering motorist can see, pedestrian accommodations if there are pedestrians, truck aprons if there are trucks, public outreach, etc. etc. Bow TIE Fighter posted:Question: why do the northbound legs swerve right before the roundabout? Wouldn't it make sense for them to just be straight like the exit lanes? It's to slow people down before they hit the roundabout. You don't want it sneaking up on someone.
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Mar 23, 2012 22:14
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Cichlidae posted:
It also looks like it's there to properly align the entrance. Two for one meal deals, now at the Marquette Roundabout Cafe!
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Mar 23, 2012 22:49
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MrBling posted:Tangentially related the traffic engineering, but I really wish that the roadworks crews that end up working on these things would pay more attention to where they dig. Interesting. Do you have a link to an article for this?
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Mar 24, 2012 02:14
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nimper posted:It also looks like it's there to properly align the entrance. Two for one meal deals, now at the Marquette Roundabout Cafe! Oh, that's in Marquette? My boss is from Marquette, and he talks about it constantly. Thinks he's Superior or something  There is debate in the roundabout community as to whether left-offset or radial approaches are better. I'm used to the radial approaches in France, so that's what I prefer. You can get better deflection as they enter by ramming them in roughly perpendicular to the circle.
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Mar 24, 2012 02:40
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Jonnty posted:I've always thought speedbumps that somehow only activated if you were actually going at above the desired speed were a good idea - especially given that I live in a neighbourhood with particularly annoying ones even if you're going under 20mph (and ones, thankfully mainly gone now, that would scrape the bottom of your car and gently caress up your wheel alignment if you do them at more than 5mph.) Assuming the impact caused by these is no worse than your average speed bump, what's the problem? Mahmoud Ahmadinejad posted:A friend of mine once watched a fully laden fire truck blow it's rear axle by going over a ridiculous speedbump at ~50 mph. Apparently if you've got a big tank full of water sloshing around in the back you shouldn't do that.
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Mar 24, 2012 09:51
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Mahmoud Ahmadinejad posted:A friend of mine once watched a fully laden fire truck blow it's rear axle by going over a ridiculous speedbump at ~50 mph. Apparently if you've got a big tank full of water sloshing around in the back you shouldn't do that. By the way! Mahmoud Ahmadinejad is arguably the world's most famous traffic engineer. Food for thought.
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Mar 24, 2012 21:34
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Cichlidae posted:By the way! Mahmoud Ahmadinejad is arguably the world's most famous traffic engineer. Food for thought.
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Mar 24, 2012 21:42
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grover posted:Where his largest contribution was the demonstration of improving traffic flow by executing bad drivers. Or so the internet tells me. He has a doctorate. I really wonder what his thesis is about.
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Mar 24, 2012 21:58
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Cichlidae posted:He has a doctorate. I really wonder what his thesis is about. In all seriousness, you've got me curious now, too, but google is turning up very little.
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Mar 24, 2012 22:30
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I found the card catalog for his university's library but can't search it because it wants IE only. Anyone who speaks farsi is welcome to grab this torch and run with it: http://translate.googleusercontent....GLxKxuqHtCzb6lg
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Mar 25, 2012 18:08
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DoctorWhat posted:In NYC on the FDR Drive going uptown, the 96th Street exit is totally hosed up. The second-avenue-Subway idiocy doesn't help. The things's a mess of directional lights that prioritize southbound-on-the-FDR over people getting off by twisting the exit around so that it crosses the main lane. Why would they do that and how can it be fixed? Since you called the 2nd ave. subway "idiocy," I'm guessing you've never ridden the 4/5/6? The Lexington Ave. line is so incredibly overcrowded, I can't wait for the Second Ave. line.
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Mar 25, 2012 18:18
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BrooklynBruiser posted:Since you called the 2nd ave. subway "idiocy," I'm guessing you've never ridden the 4/5/6? The Lexington Ave. line is so incredibly overcrowded, I can't wait for the Second Ave. line. I've always been amazed at how the Lexington Avenue line alone carries more riders per day than the entire rail transit system in any other city in the US.
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Mar 25, 2012 19:40
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Dominus Vobiscum posted:I've always been amazed at how the Lexington Avenue line alone carries more riders per day than the entire rail transit system in any other city in the US. Having been one many times, it doesn't amaze me at all. GodDAMN is the Lexington Ave. line crowded.
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Mar 26, 2012 01:40
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BrooklynBruiser posted:Since you called the 2nd ave. subway "idiocy," I'm guessing you've never ridden the 4/5/6? The Lexington Ave. line is so incredibly overcrowded, I can't wait for the Second Ave. line. I ride the 4/5/6 every day or so, and it is obscenely overcrowded, and the idea of the 2nd Avenue Subway isn't BAD per se, but the displacement of buisness, traffic problems, and mismanagement involved is cartoonish in its ineptitude. So while the idea of a Second Avenue line isn't idiotic, the implementation is frustrating and long overdue, which makes it even more frustrating.
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Mar 26, 2012 01:43
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DoctorWhat posted:I ride the 4/5/6 every day or so, and it is obscenely overcrowded, and the idea of the 2nd Avenue Subway isn't BAD per se, but the displacement of buisness, traffic problems, and mismanagement involved is cartoonish in its ineptitude. Varance fucked around with this message at 04:06 on Mar 26, 2012 |
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Mar 26, 2012 03:58
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Knockknees posted:gently caress, I hate to think of an ambulance racing to the hospital going over that. And, isn't this the thread where I read about a police officer dying from a snapped neck speeding over a speed bump? I know this isn't as high as those but, yeah, seems like not a great idea maybe. Pretty sure ambulances and police would have transmitters that make the bump not activate.
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Mar 26, 2012 11:10
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Hippie Hedgehog posted:Pretty sure ambulances and police would have transmitters that make the bump not activate. Electronics fail all the time.
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Mar 26, 2012 12:08
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Hippie Hedgehog posted:Pretty sure ambulances and police would have transmitters that make the bump not activate. A large proportion of municipalities (Hartford included) don't even use pre-emption. The equipment is expensive, and they're responsible for upkeep, which is a burden many are reluctant to shoulder. On top of that, our DOT's official policy is that pre-emption is for fire trucks only - ambulances are strictly off-label, which means if there's an accident caused by it not picking one up, it's the ambulance's fault, not ours. KozmoNaut posted:Electronics fail all the time. If it gets snowplowed a couple of times, who knows what would happen?
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Mar 26, 2012 12:28
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KozmoNaut posted:Electronics fail all the time. Agreed. If I designed such a system, I would try to make it so that if power failed, or the speed radar failed, or anything failed at all, it should NOT activate. I.e. "locked into place" should be the default state unless a magnetic coil is powered, which pulls the support out, or similar. I'm pretty sure the reason that thing was in the news recently is that it has just been tested over a Swedish winter, and as I understood it it came out OK. Edit: A google-translated excerpt from the Swedish transport authority's report on the project, looks fairly promising but seems like they are not rolling it out on a big scale yet. quote:The project aimed to develop an active speed bump that makes it possible to combine good accessibility and safety for professional drivers with low speed and a safe traffic environment for vulnerable road users such as pedestrians and cyclists. Hippie Hedgehog fucked around with this message at 12:50 on Mar 26, 2012 |
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Mar 26, 2012 12:37
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Hippie Hedgehog posted:Agreed. If I designed such a system, I would try to make it so that if power failed, or the speed radar failed, or anything failed at all, it should NOT activate. I.e. "locked into place" should be the default state unless a magnetic coil is powered, which pulls the support out, or similar. But that doesn't cover the electronics in the emergency vehicles. Presumably a relatively standard RF system will be used. What if something happens to be jamming the signal or causing interference? What if the transmitter in the vehicle fails in a silent manner? I have an electronics-related education and my dad has been working with this kind of stuff for over 30 years. I have helped him troubleshoot RF-related problems before and while these errors are very uncommon, they do occur from time to time. And while they claim to have tested the system's resilience to gravel etc., all mechanical systems wear out. How well will the system work in 5 or 10 years time?
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Mar 26, 2012 13:16
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Isn't the point of speed bumps to improve safety? Seems like such a drastic system would cause more accidents, injuries and possibly deaths than it will ever save. Most people who speed do not in fact crash. Things are different when they hit a 6inch high steel plate on the other hand. Seems like at best hundreds of dollars worth of damage and at worst death is a bit of a stiff penalty for speeding.
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Mar 26, 2012 17:54
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Seems like a more sane way to do it would be to have two metal plates which are hinged on the outside but not on the inside, with the one that cars will run over first in the normal direction of travel on the top of the two. Put the same hardware that creates this 'speed bump' underneath but make it wider. Cars going too fast will still get a shock, but instead of being a narrow and steep bump, it's a more noticeable and less evil wide, slanted gap. When pre-empted or approached by a car at normal speeds, an actuator raises and the plates level out to something on par with the temporary plates installed during road work.
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Mar 26, 2012 23:32
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When I was in europe I noticed many of the level crossings there had these little ~1m metal ramp things in front of the railways. When the crossing guards go down, these plates raise up so that a car trying to enter the track would hit it, but a car already on the track could drive over it, pushing it back down and letting them escape. Seemed like a pretty good idea, what with the amount of idiots trying to play chicken with trains.
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Mar 26, 2012 23:48
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Baronjutter posted:When I was in europe I noticed many of the level crossings there had these little ~1m metal ramp things in front of the railways. When the crossing guards go down, these plates raise up so that a car trying to enter the track would hit it, but a car already on the track could drive over it, pushing it back down and letting them escape. Seemed like a pretty good idea, what with the amount of idiots trying to play chicken with trains. Sounds foolproof, doesn't it? Well, almost...
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Mar 26, 2012 23:53
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Cichlidae, is there any news on the I-84 Waterbury widening? Particularly exits 23-25A in each direction really make make my commute miserable. I'm hoping that after the fiasco with the widening through Cheshire they'll do a good job the first time.
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Mar 28, 2012 00:04
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After weeks spent in VISSIM, I've got the solution to the Route 34-New Haven problem. It's still going to mess up the freeways pretty badly, but at least it's something of an improvement over the no-build. Edit: ^^^^ That's not my district, unfortunately, but I haven't seen it budgeted in the biennial Capital Plan, which means it probably won't be beginning in the next 2 years. Cichlidae fucked around with this message at 01:56 on Mar 28, 2012 |
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Mar 28, 2012 00:08
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