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Billy Maize posted:I would also be interested in seeing anything in Sim City you've laid out that you're proud of. I love the game and go through phases of playing and not playing, but I usually plan too big of areas and then I get bored zoning them how I want. Do you use the Network Addon Mod (NAM)? I want SimCity 5 so badly  Why, Maxis, why did you have to contract out your franchise to some imitator? I want it more complex, not simpler! I want to place ramps, customize interchanges, set lane widths and signal phasing... but I'm probably the only one who would appreciate the micromanagement. I've never heard of the NAM before. What does it allow you to do?
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Jul 28, 2009 22:01
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DeusEx posted:Not really, overall we have very lax laws considering traffic violations compared to the rest of the EU (except DUI/DWI). Tailgaiting will only be prosecuted if you were REALLY close or drive a truck. Obtaining driving licenses is indeed quite expensive though. "It works amazingly well" is kind of deceptive. I'm sure their accident rate is much higher than it is here. American roads have a much higher emphasis on safety than Indian or Chinese roads, and we sacrifice a lot of capacity and money to keep driver fatalities down. New England, by the way, does a great job of it! The safest four states to drive in are Massachusetts, New York, Rhode Island, and Connecticut. Hard to believe, eh? As to the "take down all the extra signs" concept, that's called naked roads. I'm glad to see it's catching on in Europe. Frankly, I agree that we have too many signs, and it's true that accident rates drop significantly when people are forced to pay attention like that. What's preventing that in the USA is liability. If I don't put up that "school bus stop ahead" or intersection warning or curve warning sign, and someone rear-ends a bus or drives off the road, I could quite easily get sued. It's in my best interest to put up as many signs as possible, whether or not they're really warranted.
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Jul 28, 2009 22:06
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Phone posted:How do you feel about turning left on red arrows? I've gotta say, that feels pretty weird on a gut level. While the country as a whole has a signal control bible (free PDF, check it out to see what I have to deal with), it offers a lot of leniency in what individual states can do. Some states have a flashing red or yellow arrow to indicate a permissive left turn, some (CT and RI included) have a green ball (we call them balls, to you it's a normal circular light), whereas a green arrow indicates protected movements, and the new draft MUTCD proposes even more schemes. Personally, I'm a fan of the green ball, but if I saw some evidence that another scheme was safer, I'd switch over in a heartbeat.
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Jul 28, 2009 22:11
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BadSamaritan posted:Having grown up in Rhode Island, I've always wondered about the Pawtucket S-Curves- why would you do that to a highway? That and the Thurber's Avenue curve- the exit/interchange itself is nice, but the heavily banked, densely packed curve is something else. Really that whole corridor is messed up... What I'm about to tell you is hearsay and absolutely must not be repeated, got it?  JUICY GOSSIP ALERTBack when I-95 was designed in Rhode Island, it was necessary to knock down a few buildings. Sometimes, a building was important enough that the proposed alignment would have to be changed. In Pawtucket, I-95 was supposed to be straight and smooth. Unfortunately for future generations, a powerful politician was a frequenter of an establishment of ill repute slated to be demolished by the freeway. Of course, he wasn't keen on losing his hang-out. I'm sure you can guess what happened, right?  While working at the TMC, it was a rare occurrence to actually see an accident happen in real time. Those S-curves, though... it was like clockwork. We had a camera right near the overpass there, and would catch an accident on film at least once a week. The camera itself, despite being behind guardrail and on an embankment, was demolished by errant vehicles every few months. quote:Why in general would you say New England's highways, especially Boston (oh god Boston) are like this? Is it because of the area's age/growth patterns? You mentioned in the OP it's our fault- what can we do to make it better? This merits a post of its own, because you guys are not going to believe the amount of hosed-up stuff that happened in the 70s.
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Jul 28, 2009 22:17
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Cichlidae posted:
I was just reading about Chicago's Circle Interchange, which is also a stack, but is also apparently the country's third-worst traffic bottleneck. So if a stack is already the highest capacity interchange, what do you do if it's still not enough? Spread everything out more?
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Jul 28, 2009 22:18
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Cichlidae posted:I want SimCity 5 so badly I'm having a hard time finding a good page to link you to (you can download it from sc4devotion.com on their LEX) but the NAM tries to better control the traffic and adds some new things such as light rail, new street textures and new intersections.
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Jul 28, 2009 22:20
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Undeclared Eggplant posted:I was just reading about Chicago's Circle Interchange, which is also a stack, but is also apparently the country's third-worst traffic bottleneck. So if a stack is already the highest capacity interchange, what do you do if it's still not enough? Spread everything out more? That's a turbine interchange, actually. A stack doesn't require cars to go significantly out of their way. It's a bit confusing sometimes because laypeople use "stack" to refer to any interchange with a lot of ramps. I can see why it would be congested; 300,000 cars is an awful lot. We have about the same amount going through the 95/6/10 interchange in Providence, or the 84/91/6/44 interchange in Hartford, and it leads to some massive backups if things aren't designed perfectly.
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Jul 28, 2009 22:21
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Mister Gopher posted:How do you deal with the different design and funding inputs from a variety of sources (Fed/State/Local) for highways? Do you have a separate set of guidelines for each that you must do, or what? Yes, that's how it works. Different kinds of roads are eligible for different funding sources. There are too many to list here, but basically, you'll get more federal money for something like building a busway or fixing safety problems on an interstate highway than you will for filling in potholes or building a new road. Connecticut gets 80-90% federal funding overall, which is much higher than most states. Now obviously, if you're getting federal funds, you need to meet federal design standards. It's ok to skimp a little bit, but get too slack and the feds can withdraw funding. If you work for a town, getting state funding is pretty tough unless you've got connections or it has a major impact on a state road. Most town jobs I review are a mix of local and federal funding. Town standards are stricter than state standards, overall. Providence, for example, requires granite curbing on its roads (which runs about $30/linear foot!).
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Jul 28, 2009 22:27
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KOFT posted:Have you ever come across three lane roundabouts? What do you think about them? I have, sort of. It was this one:  Hoooooooly poo poo. My French boss drove through that thing blaring opera music like it was nothing, but I think I'd have broken down and cried if someone forced me to drive there. It's simple, sure, but the sheer number of cars surrounding you makes it tough to concentrate. I'm a good driver, too! If you stuck that in America, there'd be so many accidents that they'd have a junkyard in the middle to store that day's totaled cars. I know three-lane roundabouts are smaller and calmer than that, and they're good for high-volume intersections, but I don't foresee them happening in the US anytime soon. Americans, me included, just aren't ready for something that requires them to use their brains while driving.
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Jul 28, 2009 22:32
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Jarlaxle posted:What's your expert traffic-engineer opinion on the city of Worcester, MA? Because as a driver who occasionally has to pass through there, I loving hate those roads. I don't know exactly what it is about them, but it's the only place in New England I've ever had trouble driving in. Most people I know feel the same way, and I'd like to know if there's any actual reasoning to back us up. Oh god, I don't even want to touch Worcester. I stay away from it on principle. I'm so glad that the 146 expressway got finished, so even if I ever have to go there, I can stay off the local roads. (Also because it means Rhode Island will get a new interstate once I-190 takes over 146.) Since this is my thread, though... Worcester's a total nightmare, traffic-wise. All of its roads were laid out before automobiles were around, a bunch of the intersections meet at weird angles, things are so built-up that there's no way to fix the roads, I'd be willing to bet that nothing in the city meets modern design standards. Oh well, I've seen worse. At least it's not East Longmeadow, right? 
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Jul 28, 2009 22:38
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This is one of the coolest A/T threads ever.
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Jul 28, 2009 22:52
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Hey Cichlidae, awesome thread!
voltron fucked around with this message at 16:28 on Jun 24, 2010 |
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Jul 28, 2009 22:54
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Cichlidae posted:
I figure I should actually ask some questions instead of talking about SimCity! I assume mass transit sucks in the US so much because of low-density sprawl (and most people seem to think mass transit is only for poor people) but I would still like to see what you have to say.
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Jul 28, 2009 22:58
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Lots of people posted:Great thread! voltron posted:So to ask my question, why are the lights timed such that it’s green ahead (with no traffic) while I’m at the previous light waiting at a red light. Why do the lights turn red if the previous light just turned green to move the traffic along? Why is VDOT moving traffic along Atlantic Blvd like herds of sheep? It’s loving driving me insane. It's pretty obvious the signals are coordinated, otherwise they wouldn't always line up the same day to day. My guess is that more traffic is going North than South, and the signals are coordinated so that northbound traffic doesn't have to stop. It's a tough decision for a traffic engineer to prioritize one direction at the expense of the other. My office has a sort of in-joke, that goes like this: "When in doubt, zero offset." That means that all the lights on a road turn red or green at the same time. It's safer, since people won't race to make the next light, and they all have a good idea of what's going on. Better understanding of the road means safer driving. Unfortunately, it also means more delay, but you can't please everyone. In your case, I'm sure you'd much rather get stuck at 2 or 3 lights than every single one! If VDOT hasn't acquiesced to your demands yet, chances are slim. I hate to tell you this, because I hate when people do it to me, but you CAN get it fixed if you send lots of letters to the higher-ups at the DOT. They don't care so much about delay, and they'll gladly force their engineers to do what the voting public says just to get you off their backs.
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Jul 28, 2009 23:06
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Cichlidae posted:If VDOT hasn't acquiesced to your demands yet, chances are slim. I hate to tell you this, because I hate when people do it to me, but you CAN get it fixed if you send lots of letters to the higher-ups at the DOT. They don't care so much about delay, and they'll gladly force their engineers to do what the voting public says just to get you off their backs. Haha, I pretty much gave up. If it's for safety, it's for safety. The locals definitely don't race down the street to make the green lights, because they know it'll turn red before they can make it. In that respect, I agree, it's safer. Thanks for the reply!
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Jul 28, 2009 23:08
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Billy Maize posted:I figure I should actually ask some questions instead of talking about SimCity! Yes, those are two very good reasons! Amtrak's done a decent job recently of bucking the "pauper's transport" mentality by providing only first-class and business-class on the Acela (I can't believe I'm actually praising Amtrak...), and ridership has been increasing massively. As to the density problem, the northeast is blessed (blursed?) by its ancestry. We still have tight city centers and our suburbs aren't as extensive as they are out west, so mass transit still has a chance. New York, for example, is home to half of the train riders in the whole country! Phoenix's attempt to put in light rail, though, is pretty much doomed. Unless you put a streetcar stop in front of every driveway, who's going to walk in 115 degree heat to get on the tram and make 3 transfers as they cross the suburban wasteland, when they could take their air-conditioned car straight to work instead? Don't get me wrong, light rail WILL reduce congestion and pollution, but it's not going to come anywhere near replacing automobiles as the main mode of transport. I'd be shocked if a dozen tram lines replaced 10% of Phoenix's car trips. Compare that to Washington DC - New York trips, 14% of which are currently made with our 100-year-old railroad network! Edit: Thank god they used to put the CD key on the back of the jewel case. I have no clue where the original boxes or manuals are. 
Cichlidae fucked around with this message at 02:20 on Jul 29, 2009 |
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Jul 28, 2009 23:28
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voltron posted:Haha, I pretty much gave up. If it's for safety, it's for safety. The locals definitely don't race down the street to make the green lights, because they know it'll turn red before they can make it. In that respect, I agree, it's safer. Thanks for the reply! Thanks for not ruining some engineer's day  Here's a bad customer story for you guys! My department doesn't deal with complaints directly, but I've done some digging and found some pretty hilarious things, and we'll rarely get a misguided phone call from some concerned citizen. Here is one such event! Worth reading, despite its length! Note: This is an actual email, horrible syntax preserved, names removed. Let's hope it fits in one post. Someone in serious need of help posted:Dear {boss^3},
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Jul 28, 2009 23:39
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Now that there's a lull in questions, let me tell you about Hartford. The city is filled with highway oddities, and looking at them with no context can be downright confusing. That picture shows 16 places, all in the Hartford area, where you can still see evidence of missing freeways. I said earlier that traffic is so bad because of you, but really, it's because of your parents. NIMBY was the number one killer of freeways back in the 70s. What was the death toll? Check out this diagram from Kurumi, my second-favorite source for Connecticut road details after my boss.  You see, we only managed to build about 1/3 of the freeways Hartford needed to thrive. Lack of access has stunted the city, and the freeways that were built are horribly mangled by planned connections to canceled roads. By the way, the 16 locations shown in the first image all fit into about 1/4 of Kurumi's map. That's right, there's a lot more! If there's any interest, I'll go over the canceled freeways, one by one.
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Jul 29, 2009 00:59
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Cichlidae posted:Thanks for not ruining some engineer's day Hooooooooly poo poo, that guy's nuts! Like... please lock me up in a rubber room and throw away the key nuts. I would not want to meet that guy on the street. EDIT: ^^^^ Please talk about canceled freeways!
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Jul 29, 2009 01:20
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I have lots of questions (I studied economics in school) but I'll try to restrain myself. I apologize if I accidentally ask something that's already been asked. (This thread is awesome, by the way.) Given what you've said, do you agree with The Economist's assertion that the de facto speed limit in the US is 10 over? I've often heard cops say that if they stopped everyone going 10 over there'd be riots or something to that effect. Do you think the fact that most people speed most of the time reduces respect for road laws and/or police officers? Why do some huge interchanges meet in big cities? Wouldn't it make far more sense to do those fairly distant from the city and just save the inside for local traffic? What do you think of Beijing and its 6 ring roads? Is this an efficient design? Was it worth the massive amount of bulldozing and other nonsense to make them, especially the last two? Do you ever work with economics graduates or professors? I've heard some of them take this kind of thing as contract work. Why can't protected left turns be on a timer so that, during low traffic periods, they aren't in effect? I've read a lot about what you've said on the topic so far, but I'm still curious. Why are automatic signal changers for ambulances/fire engines designed so poorly? Not only do they seem to skip a whole traffic signal cycle, sometimes it seems like it's more than one, or that it makes the red light cycle excessively long. Is driving guided by inertia, conscious thought, or something else? I can never tell if people drive slow in the fast lane because they just happen to be in that lane/need to get over at some distant point or to consciously slow other traffic down. I've heard people say both. And here is my $10,000 question. When stopped, why do some drivers leave gigantic spaces between themselves and the next car, even in tight left turn lanes and other very congested spaces? This has to be one of the worst and most avoidable forms of congestion. Yet I can never find any consistent reason why people do it. I've asked a lot of people and no one really seems to know why. Because of that, I think it must be some unconscious force, like an excessive desire for control or safety or something. Any thoughts?
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Jul 29, 2009 02:31
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Thanks for posting the Arc de Triomphe roundabout, I spent a fun evening just hanging out there and watching the craziness of the traffic, with the number of lanes seeming to change from 3 to 6 within seconds. Do you know why it is done in such a crazy way? I don't remember seeing any lane markings at all. Have you heard of any road construction methods to reduce heat generation in cities? Sydney, Australia data shows that the city are is on average nearly 20 degrees Celsius warmer than it was 150 years ago due to urban heat, and I would think roads would be one place we could try to reduce urban heat, whether by different materials or some sort of paint covering. I have no idea on this though. On Aus cities, have you come across Melbourne hook turns? they always seem to confuse visitors nicely. ZikiMike fucked around with this message at 03:25 on Jul 29, 2009 |
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Jul 29, 2009 03:01
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I'm not qualified to answer your other questions but...Arafa posted:And here is my $10,000 question. When stopped, why do some drivers leave gigantic spaces between themselves and the next car, even in tight left turn lanes and other very congested spaces? This has to be one of the worst and most avoidable forms of congestion. Yet I can never find any consistent reason why people do it. I've asked a lot of people and no one really seems to know why. Because of that, I think it must be some unconscious force, like an excessive desire for control or safety or something. Any thoughts? I was under the impression that people do this so if someone slams into them from behind, they won't be crunched into the car in front of them.
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Jul 29, 2009 03:12
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Arafa posted:I have lots of questions (I studied economics in school) but I'll try to restrain myself. It's a bit of an understatement in some places (I've seen freeways signed at 25 mph), but 10 over is a good guideline. I don't think it diminishes respect for officers; I know I feel much more reasonable toward police when I don't get pulled over for driving 75 in a 65 mph zone. But respect for the road laws? Definitely. Speed limits are some of the most imposing signs out there, other than WRONG WAY and STOP, and people already don't stop. quote:Why do some huge interchanges meet in big cities? Wouldn't it make far more sense to do those fairly distant from the city and just save the inside for local traffic? It's because most people want to get downtown, and the point of a freeway is to bring people as close to their destination as possible. Some cities use the model you're proposing; Paris is a good example. You see a lot more people using mass transit when it's available, but if it's not, the inner city will just rot from lack of patrons. quote:What do you think of Beijing and its 6 ring roads? Is this an efficient design? Was it worth the massive amount of bulldozing and other nonsense to make them, especially the last two? I have a feeling that most public works projects in China are done more to impress people and provide jobs than to actually prepare for the future. It's certainly an imposing gesture to traffic engineers, because we realize that, no matter how many highways you build, they'll always end up packed. I'm not an international policy laureate, though, so I'll leave the final explanation to those who are quote:Do you ever work with economics graduates or professors? I've heard some of them take this kind of thing as contract work. Nope, not directly. When we want a study done that analyzes the economic effects of building something, for example, we pay a contractor to do it for us. That sort of study doesn't happen often enough for the state to hire full-time staff. quote:Why can't protected left turns be on a timer so that, during low traffic periods, they aren't in effect? I've read a lot about what you've said on the topic so far, but I'm still curious. I said before that, the more motorists know about the system, the safer they drive. That's a good general rule, but there are some cases where it can lead to trouble, and changing signal operation by time of the day is one of them. A good analogy is if I had a road with a reversible lane. From 6 AM to noon, it goes northbound, and from noon to 6 PM it goes southbound. You've lived there for years, you know when it switches over. So when you get there at 11:58, even if it says the lane's closed, do you take it? Ask 1000 people, and at least one will answer yes. That's the guy we have to worry about. If people get too savvy about our timings, they'll learn to cheat the system. You'll hear more about that when I get around to discussing red lights! quote:Why are automatic signal changers for ambulances/fire engines designed so poorly? Not only do they seem to skip a whole traffic signal cycle, sometimes it seems like it's more than one, or that it makes the red light cycle excessively long. It's to be as safe as possible. What you're talking about is pre-emption, and it works in many ways. Some systems use radio communications, some listen for sirens. The signal can't tell exactly how far away the fire truck or ambulance is, so it plays it safe. It's better to delay a few motorists by 30 seconds than to risk someone t-boning an ambulance because the light turned green too early. Another interesting tidbit is that we can change which phase gets served after the pre-emption turns off. If the signal was just about to serve your phase, then gets pre-empted for 1 minute, then gets reset to the phase after yours, you're effectively waiting for about 3 cycles, which gets REALLY annoying. I can feel your pain. quote:Is driving guided by inertia, conscious thought, or something else? I can never tell if people drive slow in the fast lane because they just happen to be in that lane/need to get over at some distant point or to consciously slow other traffic down. I've heard people say both. Once you find out, tell the hundreds of PhD students who are constantly trying to perfect the driver model. The one used in VISSIM assumes that drivers won't react to other cars unless they're within a certain threshold, and then they'll react more strongly the closer they get. How far they think ahead, though? It's different for every driver, every minute of every day. quote:And here is my $10,000 question. When stopped, why do some drivers leave gigantic spaces between themselves and the next car, even in tight left turn lanes and other very congested spaces? This has to be one of the worst and most avoidable forms of congestion. Yet I can never find any consistent reason why people do it. I've asked a lot of people and no one really seems to know why. Because of that, I think it must be some unconscious force, like an excessive desire for control or safety or something. Any thoughts? Some people can't judge the lengths of their cars is one answer. Another is that we've learned (some of us the hard way) that cars can roll backward before going forward. I've heard of people who accidentally leave their cars in reverse gear and slam into someone. Davenport has another good idea up there. These are all subtle psychological problems, and I'd say most of them stem from distrust of other drivers. Bit of traffic engineering know-how: Cars stopped in a queue take up 25 feet apiece, as a rule of thumb! Have a lane that's 200 feet long? That'll fit 8 cars.
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Jul 29, 2009 03:41
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ZikiMike posted:Thanks for posting the Arc de Triomphe roundabout, I spent a fun evening just hanging out there and watching the craziness of the traffic, with the number of lanes seeming to change from 3 to 6 within seconds. Do you know why it is done in such a crazy way? I don't remember seeing any lane markings at all. There are no markings there, from what the satellite photos and memory tell me. The drivers who use it are so familiar that they just weave between other cars with no concern for where lanes begin or end. quote:Have you heard of any road construction methods to reduce heat generation in cities? Sydney, Australia data shows that the city are is on average nearly 20 degrees Celsius warmer than it was 150 years ago due to urban heat, and I would think roads would be one place we could try to reduce urban heat, whether by different materials or some sort of paint covering. I have no idea on this though. I've never heard of that being an issue here, but keep in mind that New England is relatively cold. Logically, lighter-colored roads could help with the problem. Painting the roads white, though, is a problem, since it doesn't provide adequate contrast with pavement markings. I think the MUTCD says you'd have to put the white stripes on a black background, and that's expensive. quote:On Aus cities, have you come across Melbourne hook turns? they always seem to confuse visitors nicely. Melbourne's signals along the tramways confuse me in ways hook turns never could
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Jul 29, 2009 03:45
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Civil Engineer here. I took one transportation class and probably the only thing I took away from it is to run red lights. At signalled intersections there is a point when the lights in all directions will be red. It is called the ALL RED phase and I believe it lasts for 3 seconds. It is there as a safeguard to make sure the intersection is clear before the perpendicular direction turns green. Anyway, I am all to familiar with stop and go traffic as I drive in Chicago frequently. I almost feel like idiot drivers can be blamed for slowdowns just as much as the highway design. They think that weaving in and out like a Nascar driver will save them time. Question for you, say you are driving on a 3 lane freeway(I-55 in my case(stop&go traffic)) with traffic merging in on the right. What lane typically moves the quickest? I usually stay in the middle lane...I never really go in the right lane as I fear that the Queueing would slow me down to much. If you understand what I am asking I would like to hear your thoughts on what lane moves the quickest.
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Jul 29, 2009 03:56
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It's bedtime, but don't let that stop you from asking questions. Try to ask only a couple at a time, please. You guys ask great questions, and I don't want to write too much about pedantic little things (not yet, at least.) I like to keep the text broken up with pictures every now and again! Here's what VISSIM looks like when it's simulating traffic. The colored bars on the ground represent what color the signal is.  Major props to anyone who can figure out where this is! I'd be willing to bet at least one goon lives within 5 miles of it.
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Jul 29, 2009 03:56
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fake eh seizure posted:Civil Engineer here. I took one transportation class and probably the only thing I took away from it is to run red lights. At signalled intersections there is a point when the lights in all directions will be red. It is called the ALL RED phase and I believe it lasts for 3 seconds. It is there as a safeguard to make sure the intersection is clear before the perpendicular direction turns green. I'll be devoting a full post to this sometime soon. Things like that are why I put the disclaimer in the OP. (Our red clearances are usually less than 3 seconds, though.) quote:Anyway, I am all to familiar with stop and go traffic as I drive in Chicago frequently. I almost feel like idiot drivers can be blamed for slowdowns just as much as the highway design. They think that weaving in and out like a Nascar driver will save them time. Yep, they're to blame in more ways than one. If we didn't have to design roads for the stupidest .01% of the population, we could be driving on much higher-speed facilities with more lanes. quote:Question for you, say you are driving on a 3 lane freeway(I-55 in my case(stop&go traffic)) with traffic merging in on the right. What lane typically moves the quickest? I usually stay in the middle lane...I never really go in the right lane as I fear that the Queueing would slow me down to much. If you understand what I am asking I would like to hear your thoughts on what lane moves the quickest. Due to some fun cognitive biases, it's always going to seem like your lane is moving the slowest. In theory, the leftmost lane should always drive fastest (It's the law here). If there are left entrances or exits, lane drops, narrow shoulders, or heavy congestion, then the middle lanes can be faster. When I explain basic vs. auxiliary lanes, you'll see why things are a bit more complicated than just "stay right except to pass."
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Jul 29, 2009 04:02
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Thanks for the thread! If everyone knew someone from a DOT or a traffic engineer or what have you, there would be approximately 99% less bitching due to misinformation or supposition. I just wondered about dynamic message signs, or, as you may call them in Connecticut, variable message signs or changeable message signs! I can't remember which you guys call them; it seems to vary from state to state. You mentioned that you had some sort of experience with them, so I wanted to ask what types of attributes you looked for in them. What features are important to you? What types of problems have you had with them that make technicians heads explode? Also, have you helped with writing any specs or anything for DMS contracts? If so, what goes into that process? I assume it's usually low bid, but are there manufacturers that you prefer over others? Thanks again!
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Jul 29, 2009 04:40
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They're putting roundabouts in right next to where I live on the highway here. The highway begins here at Lake Ontario (I-590) and and goes to meet up with the other interstate branches and eventually I-90. The first 2 or 3 miles of it, has always been 4 stoplights. The one I use to enter the highway gets way too many accidents a year. People going 55, tend to try and beat the lights as often as possible. They stay yellow for a long time, which I think gives people the confidence to just go for it. Unfortunately, many miscalculate the time and distance needed and careen into cars making left's or right's onto the highway. So they dropped the speed limit to 50, and that did absolutely nothing. So now it's roundabout time! They're about a month from completion, and they look horribly awkward. But I'm excited nonetheless. But the people around here are pretty scared of them, since exactly 100% of the population around here has never been through one, and I'm sure many of them hadn't even heard of them until now. You can see it here: http://maps.google.com/maps?f=q&sou...013272&t=h&z=17 The "Sea Breeze Expressway" from that soccer field North is this stretch of road. The 4 stoplights (Titus ave, Seneca Ave, Pt. Pleasant ave and Durand Blvd), are whats being converted to roundabouts. I wonder how long it'll take google maps to update with the changes to it. Didn't realize there was a streetview. But here's the light that has tons of accidents (and the one I use). Now all 4 corners of the lots here were bought up by the town, and are currently large piles of dirt. http://maps.google.com/maps?f=q&sou...12,1.66,,0,9.95 Binge fucked around with this message at 05:43 on Jul 29, 2009 |
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Jul 29, 2009 05:38
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voltron posted:Hey Cichlidae, awesome thread. I have a traffic question about a stupid light timing issue that has bugged me so much that I’ve written several E-mails to the local VDOT (Virginia Department of Transportation) to no avail. I think the reason the light is always red at DCP is that most people coming from Atlantic or Nokes turn right, some left, but mostly right at DCP. Since so few go straight they have it red. Atlantic isn't supposed to be smooth. I think the designers assumed that people would be using 28. I'm pretty familiar with the area and if you jumped on 28 you'd get to Orbital pretty quick, even quicker now with them getting rid of the lights in that area. In any case I have to contend with driving from Lowes Island area on 7 to Tysons which really is a red light traffic nightmare if you hit the wrong lights. Though when there's not to much traffic and everyone drives the speed limit or slightly below you can make it through most on green.
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Jul 29, 2009 06:32
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Very interesting thread; thanks, OP! Here's an issue I'd love to hear your input on. I'm an avid bicyclist, and there's no end of argument on the various bicycling forums out there as to what's the all-around "best" arrangement for a reasonably busy road: 1. A dedicated bike lane, or other segregated facility. 2. An outside vehicle lane that's wide enough for a car and a bike to share safely side-by-side, or 3. The bike takes the full lane and forces car traffic to change lanes to pass. Of course it's a lot more complicated than just this in the real world -- for example, a lot of bike lanes are located dangerously close to parallel-parked cars, so anyone who rides in them is practically begging to get doored. But I'm curious what sort of attention the spandex brigade gets in your simulations, and if you've arrived at any conclusions on "best practices" regarding us.
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Jul 29, 2009 06:39
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Cichlidae posted:It's bedtime, but don't let that stop you from asking questions. Try to ask only a couple at a time, please. You guys ask great questions, and I don't want to write too much about pedantic little things (not yet, at least.) It's been a number of years since I lived in CT, but I think that's west of Meriden by I-84.
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Jul 29, 2009 08:49
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Cichlidae posted:I'll be devoting a full post to this sometime soon. Things like that are why I put the disclaimer in the OP. (Our red clearances are usually less than 3 seconds, though.) There's an intersection in my city that has an all-red phase which lasts 5 seconds, instead of the standard 3 seconds found everywhere else. This can be confusing if you don't know about it. I often see people expecting the standard 3 seconds, causing the whole line of cars in the front to lurch forward only to have to wait another 2 seconds for the lights to go green. If you are further back in the queue, it's even more apparent as you see all the cars letting go of their brakes at the same (wrong) time, just to inch forward a bit and stop again, often a metre or two into the crossing lane. This phenomenon has resulted in our DOT adding very long shades on the sides of many traffic lights, so that the cars in the side lanes cannot see when the light has turned yellow. Is this kind of thing common?
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Jul 29, 2009 09:25
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Cichlidae posted:I've gotta say, that feels pretty weird on a gut level. While the country as a whole has a signal control bible (free PDF, check it out to see what I have to deal with), it offers a lot of leniency in what individual states can do. Some states have a flashing red or yellow arrow to indicate a permissive left turn, some (CT and RI included) have a green ball (we call them balls, to you it's a normal circular light), whereas a green arrow indicates protected movements, and the new draft MUTCD proposes even more schemes. Personally, I'm a fan of the green ball, but if I saw some evidence that another scheme was safer, I'd switch over in a heartbeat. Can I print this off as a "get out of jail free" card when an officer eventually pulls me over for making a left on red? As a driver, I seriously feel that protected lefts fall into two categories: 1. Unsafe intersection to yield/use own judgement 2. Cover up some retarded design or to appease some locals who go 5 miles under the speed limit An example of #1 could 6 lanes divided intersection or stuff that's on hills or around bends; fairly legit. #2 is way more common and can be found on 4 lanes divided local highways where it's completely level and visibility is whatever the weather dictates.
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Jul 29, 2009 09:33
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Why do certain places have those god awful traffic lights that are impossible to tell which color they are until you're right under them? I get it, "ha ha! Those pesky drivers will have to slow down to see if they're ok to pass through the intersection!" but really, I imagine it would just create more traffic.
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Jul 29, 2009 09:36
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Everytime a thread like this comes up I always post this link: https://www.cbrd.co.uk You think "oh a site about roads in the UK that sounds loving great fun  "Then two hours later you realise you're still reading it and that it's actually very interesting. There's also this: http://www.pathetic.org.uk/ Which is quite amusing.
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Jul 29, 2009 14:49
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Apparantly VISSIM has a trial that last 2 monthes - I'm downloading it right now to give it a shot. Any other good/fun software you can recommend for us to try out? I'd like to try to create some of the interchanges you mentioned above! Edit: Okay so by good/fun I don't mean VISSIM. Talk about being in over my head! MarshallX fucked around with this message at 15:41 on Jul 29, 2009 |
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Jul 29, 2009 15:31
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Great thread OP, I've been making an effort to complain less about the brainless idiots who must have designed my commute. problematique posted:if you jumped on 28 you'd get to Orbital pretty quick, even quicker now with them getting rid of the lights in that area. This has been so weird to see, watching 28 become a highway (complete with a speed limit raise!)
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Jul 29, 2009 16:05
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Fantastic thread, if I had decided to do any other discipline of engineering I think it would have been traffic. Requesting Coordination 102. The time-space diagrams illustrate how this works on a one dimensional plane, but what about at the intersection of large roads? Is there a way to render this in 3D or a better way than to just have two separate diagrams viewed in parallel? What are the metrics used and how are they weighted against each other? I'm thinking of a situation like if you can increase traffic by x cars per hour by making a few people wait an extra 30 seconds, versus improving it 1.5x per hour by making them wait 2 minutes. Everything here in San Diego is based on sensors, is there a lot of data fed back to a central database for optimization? I feel like with so much continuous data collection it should be trivial to write algorithms to minimize wait times.
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Jul 29, 2009 16:41
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OP - anybody who has ever driven by, in, or around DC has had to deal with this monstrosity. On top of being incredibly confusing (I've driven through it numerous times on the way to and from school, and I still get off on the wrong exit), it also seems like the amount of congestion resulting from it is constantly a problem. Can you see any logic behind what the engineers building this interchange were thinking? Also, what's your opinion of driving in DC? I'm convinced that the murder rate in that city is a result of a road system that could turn Joanie Mitchell into a mass murderer.
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Jul 29, 2009 19:17
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