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Opensourcepirate posted:Great thread. Voted 5 and went hog wild. The only problem I see with that is that it's not immediately obvious what the flashing means. As I said before, for the moment, there's not really a consensus as to how permissive/protected signals should work. In a few years, when the new MUTCD comes out, hopefully we'll have a national (and Canada, too) standard to work with. From what most states are saying, it looks like it'll be green arrow / green ball / red arrow for protected / permissive / no turn. It's really amazing we've made it so many decades without a real consensus.
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Aug 3, 2009 02:35
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How would you improve this intersection of doom? http://maps.google.com/?ie=UTF8&ll=...,212.68,,0,9.07
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Aug 3, 2009 02:58
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JackBoCracken posted:How would you improve this intersection of doom?  That one was fun, thanks! I'm sure you can tell by now that fixing up this kind of intersection is mostly a matter of keeping the intersections at 3- and 4-legs, at about 90 degree angles. Additionally, I had to keep the intersections far enough apart to allow for the queues that could form there. I also turned some of the old pavement into cul-de-sacs (haha, it's French for "bag's rear end") to provide access to the driveways I cut off. The best part is, I didn't have to bulldoze any buildings! With a million dollars or so, you could make this a reality. Edit: Uhhhh, forgot to attach the image. Cichlidae fucked around with this message at 03:32 on Aug 3, 2009 |
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Aug 3, 2009 03:22
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haha, that's amazing! I doubt the people would give up even an inch of their park but it would make it loads safer...
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Aug 3, 2009 03:49
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JackBoCracken posted:haha, that's amazing! I doubt the people would give up even an inch of their park but it would make it loads safer... If they give up a couple thousand square feet, they can regain twice as much on the other side. Stick in some fake brick sidewalks, couple benches, and a fountain, and they'll buy it. We took a public involvement class a couple weeks ago, and the number 1 thing I took from it is that, even if you can't satisfy everyone's wishes, you can at least get them not to block the project if you throw enough time and money at them.
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Aug 3, 2009 03:56
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Here are two awesome on-ramps. Basically if you're exiting the Allen Parkway onto I-45, they made sure to include a pucker-zone on both the north and southbound entrance ramps. You round the northbound entrance (it's a 30 MPH ramp in a sports-car, and its blind) and you're thrown onto another ramp that joins 45, where the traffic is already doing 50. You can't see poo poo until you've already began merging so that makes it even more fun. The southbound isn't as bad sight-wise (although still bad), but you get tossed into a 60 MPH zone's left-lane, which during non-peak hours, is actually moving about that fast. Good times. At least I-10 is awesome now. Thanks so much for all of the useful information you've posted in this thread. It's nice to see someone so well versed in their profession teaching others about something relevant to their everyday life. grillster fucked around with this message at 08:32 on Aug 3, 2009 |
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Aug 3, 2009 08:29
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grillster posted:Here are two awesome on-ramps. Oh jeez, what the hell is up with that interchange? It's waaaaaaay more complicated than it needs to be. If I had to guess, I'd say there was supposed to be another freeway heading to the East from there, but it got canceled. There's really no other justification for all of the left-hand ramps. Heck, by modern standards, even if there were another freeway, they wouldn't be justified. They obviously went through the effort of putting in collector/distributor roads there, but they're hardly being used! quote:Thanks so much for all of the useful information you've posted in this thread. It's nice to see someone so well versed in their profession teaching others about something relevant to their everyday life. You're welcome! I'm really glad you guys appreciate it. Maybe I'll have to change my career path so I can make another thread in a few more years 
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Aug 3, 2009 12:18
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Excellent thread. I just spent two years working as a transportation planner, though I'm probably going to move toward land use planning once I'm done with my master's degree. I'm still a bit of a roadgeek at heart, but I don't think I'd want to make a career out of traffic engineering. Having to do anything with the Green Book bores me to tears. I'd rather draw lines on maps and let other people work out the details. Still, Synchro is a lot of fun to play with. Anyway, for an actual question: what do you think of the proposed MUTCD updates?
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Aug 3, 2009 15:03
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I pity anyone who lives on treasure island because fuuuuuck http://maps.google.com/maps?f=q&sou...002401&t=h&z=19 There's about 10 car-lengths between the stop sign and a merge with 50+ mph traffic (as high as 70 sometimes). Fuuuuuck!
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Aug 3, 2009 16:30
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Dominus Vobiscum posted:Excellent thread. I just spent two years working as a transportation planner, though I'm probably going to move toward land use planning once I'm done with my master's degree. I'm still a bit of a roadgeek at heart, but I don't think I'd want to make a career out of traffic engineering. Having to do anything with the Green Book bores me to tears. I'd rather draw lines on maps and let other people work out the details. Still, Synchro is a lot of fun to play with. My boss "asked" me to look through every state's reply to the revisions, as well as some private concerns. Here's what people think, in a nutshell: At least half of the comments are some form letter from RV enthusiasts. They're very happy that roadside signs will now show which hotels, gas stations, etc. are RV-friendly. At the same time, they think the little RV plaque is too small. Old people!  For the most part, the proposed revisions are going over well, with some exceptions. Everyone's hating on the FYG (Fluorescent Yellow-Green) signs for pedestrians. The consensus seems to be that, since they draw so much attention, they should be used specifically for school zones, and not just for peds. New Jersey doesn't like the new section on jughandle signs, and Delaware doesn't like all the new toll signage, but that shouldn't surprise anyone who's ever driven through those states. There are some other signs that people don't like, for example, one says something like "Pull over and let others pass if there are more than 3 cars behind you." Personally, I'm looking forward to it, since private roads will now be held to the same standards as public roads. I'm also looking forward to the "nothing can be mounted to the back of a stop sign" rule, so I can go piss off the shopping plaza down the street by running their stop sign (they're even mounted at the improper height!) and sticking my tongue out at them, going "NYA NYA PUT UP SOME LEGAL SIGNS YOU NINNIES!" There are some parts I don't like, though. One of them is, due to our aging population (surprise surprise), they want to change the visibility standard from 40:1 to 30:1. Currently, a 1-inch-high letter is considered to be legible from 40 feet away. They want to make our lettering 4/3 bigger than it currently is. That doesn't seem like a lot until you consider this: 1) We have tens of thousands of signs that would need to be replaced because of this, all in 5 years, whereas we normally leave them up for 20 before they need to be replaced. 2) By making the sign 4/3 bigger in each dimension, we make the sign 1.8 times larger, which is 1.8 times heavier and 1.8 times as susceptible to ice and wind loading. 3) This means we'd have to replace most of our big sign supports, which, by the way, cost around a quarter million bucks apiece. 4) But every state would need to replace them at the same time, driving prices through the roof, and... you get the picture. It'd cost Connecticut, a small state, hundreds of millions of dollars at least. Luckily, several states have caught on to this, and we might be able to block it.
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Aug 3, 2009 17:24
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Socket Ryanist posted:I pity anyone who lives on treasure island because fuuuuuck What's  so  bad  about  stop-controlled  ramps? We've knocked out hundreds of them, many on an interstate no less, and still have dozens. One of them is consistently the #1 most dangerous spot in the state.
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Aug 3, 2009 17:38
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^^^Right on! Rt 15 is infested with these and there's fender-benders on the ramps literally every day with the occasional catastrophic wreck during failed merges thrown in for good measure. The ensuing traffic jams (every loving day) from rubber-necking and condensing lanes around the wrecks are miserable. The 91/95 interchange in New Haven, especially the parts where Rt 34 sticks its dick into the mess. What the gently caress and is it even possible to fix it? Specifically, everything involving the Q Bridge and, if you have time after that, the whole 91S debacle. It seems like the only answer is "more lanes," but that's not very likely, ever. Is a better design possible or are we just hosed forever? Digger-254 fucked around with this message at 18:23 on Aug 3, 2009 |
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Aug 3, 2009 18:16
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Cichlidae posted:MUTCD It seems to me that the increased visibility requirements would be fine if it were implemented with a long enough time frame that substandard signs get replaced as their service life is over. Down here in Florida, most signs already meet the higher visibility standards (take a guess as to why), but having driven a lot in other states recently, I can see the problem. I like the new diagrammatic guide signs. The existing lane diagrams can be pretty confusing at 70mph if you're in an unfamiliar urban area. What do you think of Clearview?
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Aug 3, 2009 18:17
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Are the MUTCD comments online? I found this page with the changes (I think): http://mutcd.fhwa.dot.gov/resources/proposed_amend/index.htm Lost Downtown posted:^^^Right on! Rt 15 is infested with these and there's fender-benders on the ramps literally every day with the occasional catastrophic wreck during failed merges thrown in for good measure. The ensuing traffic jams (every loving day) from rubber-necking and condensing lanes around the wrecks are miserable. Obviously the road is just not meant for 75 mph traffic, and doing any work on it will rain down hell from the locals.
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Aug 3, 2009 18:38
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smackfu posted:Are the MUTCD comments online? I found this page with the changes (I think): I know, I know... it just blows my mind that when they were designing the ramps not only did some guy say "Hey guys, lets put half the on-ramps on the wrong side of the underpasses!" but then enough other people were like "Yeah, awesome!!" that it actually loving happened. I'm imagining a similar discussion happened when the question of the angle of the off-ramps was introduced, and the reaction was so overwhelmingly positive that they decided to put the two together in all those cases. Many high-fives were then exchanged while the very first two cars smashed together in the background.
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Aug 3, 2009 19:12
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I was bored and read through the 343 page MUTCD changes presentation. Stuff I noticed: STOP (Except Right Turn). Really? That seems like a bad idea. No all-caps for street name signs, which I thought was the standard practice. "All-way" instead of "4-way" stops. "RIGHT TURN ON RED MUST YIELD TO U-TURN". What does that even mean? Would anyone understand that while driving? Those fluorescent green signs are hideous. There's now a burro warning sign. OK... I guess I'm not that bored, because I could only handle 150 pages of that.
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Aug 3, 2009 21:26
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Lost Downtown posted:^^^Right on! Rt 15 is infested with these and there's fender-benders on the ramps literally every day with the occasional catastrophic wreck during failed merges thrown in for good measure. The ensuing traffic jams (every loving day) from rubber-necking and condensing lanes around the wrecks are miserable. We're taking out more every year! Next on the list is the River Road ramp, and hopefully Route 175 after that. quote:The 91/95 interchange in New Haven, especially the parts where Rt 34 sticks its dick into the mess. What the gently caress and is it even possible to fix it? Specifically, everything involving the Q Bridge and, if you have time after that, the whole 91S debacle. It seems like the only answer is "more lanes," but that's not very likely, ever. Is a better design possible or are we just hosed forever? Well, guess what! It's being reconstructed as part of the Q-bridge project, getting rid of the left ramps and completely redesigning the interchange. The ramp from 91 South to 95 South is getting an extra lane added, as well. I'm not saying there won't be any more traffic in New Haven, but between that and 5 lanes each way over the bridge, things should be much more bearable.
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Aug 3, 2009 21:48
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smackfu posted:"RIGHT TURN ON RED MUST YIELD TO U-TURN". What does that even mean? Would anyone understand that while driving? If someone on the cross street is making a u-turn, anyone turning right on red would have to yield to them. That's an odd one, given that they're trying to reduce the amount of text on signs. I can't imagine it'd be used anywhere other than intersections with a history of right-turning vehicles running into people making u-turns. Why not just prohibit u-turns instead?
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Aug 3, 2009 21:50
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Dominus Vobiscum posted:It seems to me that the increased visibility requirements would be fine if it were implemented with a long enough time frame that substandard signs get replaced as their service life is over. Down here in Florida, most signs already meet the higher visibility standards (take a guess as to why), but having driven a lot in other states recently, I can see the problem. I'm definitely down with the diagrammatic signs, too. We have quite a few already, and they make it extremely easy to find which lane I should be in. As to the phase-in period, we could probably get an exception, but it could jeopardize our shot at federal funding. We bent over and took it when the feds pushed us to switch to metric (while most states just got an exception), and ended up having to switch back to imperial units a couple years later because we were losing so much money with metric. As to Clearview, anything that can get us more visibility without actually enlarging the letters is good. We still have some signs around that use the old old font from 30 years ago, and it's pretty obvious, so I assume that putting up a new font will also garner some attention. That's always a good thing when it comes to signs.
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Aug 3, 2009 21:54
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smackfu posted:Are the MUTCD comments online? I found this page with the changes (I think): Yep, that's the page. Unfortunately, you can only get just text (which seems to leave out tables), or just figures (not including tables). I open the text on one monitor and the tables on the other. Hardly ideal, but they give us dual monitors for a reason, I guess! quote:The offramps are pretty bad too. Signed at 15 mph. I took out one of the caution signs at the exist 37 in Darien once because the roads were wet and my car just went straight when I braked. The funny part is that the speed "limit" signs on the ramps aren't even legal restrictions. Yellow sign? Not enforceable. It's just a suggestion. (Again, not an excuse to drive like an idiot, you can still get pulled over for reckless driving!) As to the Parkway's design speed, considering it was made in the 1930s, I'd guess it's somewhere around 40 mph. It's a good thing trucks aren't allowed, or it'd be crash city day in and day out.
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Aug 3, 2009 21:58
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Lost Downtown posted:I know, I know... it just blows my mind that when they were designing the ramps not only did some guy say "Hey guys, lets put half the on-ramps on the wrong side of the underpasses!" but then enough other people were like "Yeah, awesome!!" that it actually loving happened. I'm imagining a similar discussion happened when the question of the angle of the off-ramps was introduced, and the reaction was so overwhelmingly positive that they decided to put the two together in all those cases. Many high-fives were then exchanged while the very first two cars smashed together in the background. Hell, you think that's bad, there was actually an at-grade crossing on the Parkway for 2 decades after it opened. Kind of like Route 9 is now, actually. For those who aren't familiar, CT 9 is a 50-mile-long freeway with three at-grade intersections right in the middle.  See that lighter-yellow section in the middle? Yeah... 
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Aug 3, 2009 22:03
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smackfu posted:I was bored and read through the 343 page MUTCD changes presentation. You must have been REALLY bored. quote:Stuff I noticed: To me, too, but every sign has a context. Perhaps it's at a channelized right turn lane, like so:  Or, the MUTCD could just be retarded. It is still a draft, after all. quote:No all-caps for street name signs, which I thought was the standard practice. WAS standard practice. All street signs from now on will (probably) be put in Proper Case. Surprise! quote:"All-way" instead of "4-way" stops. Well, when I get to an intersection with a 4-way stop, I don't want to have to look around and count the legs to make sure there isn't a fifth free-flow leg. quote:"RIGHT TURN ON RED MUST YIELD TO U-TURN". What does that even mean? Would anyone understand that while driving? I certainly do, but that's probably just because I'm a traffic engineer. I wouldn't put a sign up at all, though. People should already know they need to yield. SHOULD. Edit to add, in response to Dominus Vobiscum: I agree, it really goes against the MUTCD's goals. A channelized right turn lane, cat tracks for the U-turn, or NTOR would all be appropriate. quote:Those fluorescent green signs are hideous. They sure are, that's why so many states want to keep them just around school zones. "I say, what in the blazes is that vomit-coloured sign doing there?" "I daresay we'd best drive carefully, Percival. Methinks we've entered a cretin zone." quote:There's now a burro warning sign. Hey, we've gotta get New Mexico to sign on to this. What can we do to make them happy? What IS there in New Mexico, anyway? Oh, I know! quote:OK... I guess I'm not that bored, because I could only handle 150 pages of that. I thought so. Policy books are drier than Mercury in August. Cichlidae fucked around with this message at 22:16 on Aug 3, 2009 |
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Aug 3, 2009 22:14
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Cichlidae posted:To me, too, but every sign has a context. Perhaps it's at a channelized right turn lane, like so:  Where I've seen these, they just aren't signed. Aha, Google revealed this, which was probably why they standardized it: http://www.pacode.com/secure/data/067/chapter212/s212.107.html quote:When a major traffic movement at an intersection is a right turn, the Except Right Turn Sign (R1-1-1) may be placed below the Stop Sign (R1-1) on that approach to minimize the total delay at the intersection. When this sign is used, Stop Signs (R1-1) are required on all other intersection approaches except for the approach with a corresponding left-turn movement (And I really just looked the pictures.)
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Aug 3, 2009 22:24
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Sorry if I missed this or you don't want to elaborate, but what kind of hours and pay do you get doing this? What changes will come to your job with advancement?
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Aug 3, 2009 22:25
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smackfu posted:Here's the amusing example. Yeah, that makes sense. If your predominant movement is frickin' tractors, though, you may as well just slap up four STOP signs and call it a day. Colawa posted:Sorry if I missed this or you don't want to elaborate, but what kind of hours and pay do you get doing this? What changes will come to your job with advancement? I work 8 hours a day, Monday to Friday, and get about $29 an hour. We have a wage freeze for the next year or so, maybe longer, so I don't expect that to increase much for a while. As to advancement, with so many people retiring lately, I hope I can get a bump up sooner or later. I'll probably move to the private sector before long, though. There's only so much you can learn in one place, and I have an appetite for knowledge!
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Aug 3, 2009 22:31
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What's the deal with this: I used to drive this (green) route every day. You're going east on cross bronx expressway and want to go north on bronx river parkway. You have to exit off cross bronx onto a local street, take the "U" ramp, cut across the local street and take the ramp onto bronx river parkway (which has a traffic signal). It doesn't help that a lot of people coming from the local (yellow) street want to go straight which means they have to merge right and people going the green way need to merge left to take the U ramp. Sometimes you get lucky and the light is red at the intersection north east of the U ramp and you can go w/o problems. At some point I got fed up and just started going through the intersection (left and another left) instead of trying to take the U ramp. I apologize if my description is a little confusing.
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Aug 3, 2009 22:42
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PessiMister posted:What's the deal with this: I get what you're saying; it's a weaving issue. Looks like there just aren't that many cars (or weren't, when it was designed) making the maneuver that you do, otherwise it'd be advantageous to build a flyover ramp to add a direct movement from 95 N to the Parkway N. Or, it could be that they want to limit the traffic taking the Parkway by making it difficult to access. A third option is that one or more of the roads there used to be a toll road, and the interchange was designed to specifically funnel traffic through booths. All of that's pretty much trumped, though, by this monster a mile up the road:  
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Aug 3, 2009 22:57
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Really interesting thread, thanks. What's your take on Magic Roundabouts, such as this beauty in Swindon, UK?
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Aug 3, 2009 23:13
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SelfHealer posted:Really interesting thread, thanks. What's your take on Magic Roundabouts, such as this beauty in Swindon, UK? An interesting novelty, but they don't seem particularly safe, and I'd certainly go out of my way to avoid driving in one. I wouldn't even consider putting in a new one. I understand they're a source of national pride for England, which would prevent removal for safety reasons. I just bet a couple signalized intersections would do as good of a job without confusing the hell out of everyone who's not familiar with it.
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Aug 3, 2009 23:19
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I'd be interested to hear your thoughts on Highway 401 in Ontario, specifically in Toronto. Here are 3 big interchanges: http://maps.google.ca/maps?f=q&sour...=k&z=16&iwloc=A http://maps.google.ca/maps?f=q&source=s_q&hl=en&ie=UTF8&t=k&ll=43.729429,-79.447889&spn=0.011614,0.023153&z=16 http://maps.google.ca/maps?f=q&source=s_q&hl=en&ie=UTF8&t=k&ll=43.716062,-79.51679&spn=0.011616,0.023153&z=16 This stretch of the 401 is busiest freeway in North America I believe. It can be 16 lanes across and in certain areas it's almost always a traffic jam (like the first link).
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Aug 3, 2009 23:21
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swalk posted:I'd be interested to hear your thoughts on Highway 401 in Ontario, specifically in Toronto. This one is under construction in the picture, so it's not really a fair assessment, but... Only two through lanes North and South seems to be a bottleneck, if the traffic shown there is any indication. There are two left entrances, which aren't a good idea. Left exits and entrances on the C/D roads normally don't count, but since they have so many lanes, it could exacerbate the problem. By the way, this kind of freeway is known as dual-divided, or dual-dual. Much nicer, all right exits and entrances, and each approach only has one exit, which then splits. Bonus points for the rail down the middle of the interchange. That's a great way to implement mass transit in a shared right-of-way. One small drawback is that eastbound traffic in the inner lanes of 401 can't exit. Overall, I consider this interchange to be very well designed. Left entrances and exits galore! Oh dear, that's not how to build a freeway... The two exits from 400 northbound should be consolidated into one. There's only one ramp from the inner lanes of 401. For full access, three more are needed, but it's not necessary. And there is no access to the inner lanes, either. Oh dear! quote:This stretch of the 401 is busiest freeway in North America I believe. It can be 16 lanes across and in certain areas it's almost always a traffic jam (like the first link). Yep, as I've said before, there's no way to build a freeway that won't jam. It's all a matter of how long it lasts before it does 
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Aug 3, 2009 23:47
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Cichlidae posted:It's a good thing trucks aren't allowed [on Rt 15], or it'd be crash city day in and day out. As I was driving up 15 on my way from the NYC metro area to western MA last week, I had the awesome luck to be in the left-hand lane just preceding a big-rear end tractor trailer entering by the ramp immediately south of the West Rock tunnel. I'm not sure how the timing worked out exactly (luck again? I can't imagine the cops camp out 15's onramps waiting for trucks to try and sneak on?) but a police cruiser came TEARING up the onramp in pursuit of the truck with his lights on, and either because of him or just because of what was going on, the car traffic came to a halt. This allowed the truck driver to continue through the tunnel in the middle of the 2 lanes (the only way he could fit) with the cruiser following him, lights on, till he exited at the next offramp. I'm still not sure whether the truck driver was trying to get away at first, or if the cop ordered him through knowing he wouldn't be able to turn around. Gave me flashbacks to when one of the Manhattan-Jersey tunnels got shut down a year or two ago by a trailer trying to drive through and getting its top peeled off like a can of sardines. Anyway, yea. The Merritt and its avg-75-mph-in-a-55-mph-zone traffic -- especially at night, with the nonexistent lighting the parkway has -- scares the bejeezus out of me every time. Sorry for the e\n. To try and be on topic: have there been, or are there will be any, plans to try and curb the speeding on 15, or is it just one of those facts of life?
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Aug 4, 2009 01:16
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bitprophet posted:As I was driving up 15 on my way from the NYC metro area to western MA last week, I had the awesome luck to be in the left-hand lane just preceding a big-rear end tractor trailer entering by the ramp immediately south of the West Rock tunnel. I'm really glad he got caught! The few trucks that are allowed on the Parkway are required to get a special permit, and for good reason. quote:To try and be on topic: have there been, or are there will be any, plans to try and curb the speeding on 15, or is it just one of those facts of life? As I mentioned earlier, there are really only two ways to stop speeding: changing the geometry to force people to drive slower, and ramp up enforcement. The former wouldn't work very well on an expressway, where people expect to be able to speed. The latter is feasible, but it's out of my hands; when and where the cops choose to set up speed traps is up to them.
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Aug 4, 2009 01:35
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Dominus Vobiscum posted:That's an odd one, given that they're trying to reduce the amount of text on signs. I can't imagine it'd be used anywhere other than intersections with a history of right-turning vehicles running into people making u-turns. Why not just prohibit u-turns instead? Sometimes people need to make u-turns! (roads with medians and they need to enter a driveway on the opposite side).
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Aug 4, 2009 02:22
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Socket Ryanist posted:Because people making U-turns have the right of way (as they have a green light, and not a red one). The sign is just informative. I meant that only in specific cases of intersections where there is a history of RTOR vs u-turn crashes, where they'd likely be placing these signs. Prohibiting RTOR or u-turns would probably be more effective in solving a safety issue than putting up a sign with a lot of text on it reminding people of something they should already know. Of course, it'd be dependent on how removing RTOR would affect the operation of the intersection, too.
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Aug 4, 2009 02:32
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Dominus Vobiscum posted:I meant that only in specific cases of intersections where there is a history of RTOR vs u-turn crashes, where they'd likely be placing these signs. Prohibiting RTOR or u-turns would probably be more effective in solving a safety issue than putting up a sign with a lot of text on it reminding people of something they should already know. Of course, it'd be dependent on how removing RTOR would affect the operation of the intersection, too. We could also invest in better driver training, or make the rules for getting a license more stringent... naaaaaaaah. 'Merca! What I mean is, I feel that driver's education in the USA is really lacking in quality. The fact that some people (a majority, even) don't know how to assign the right of way is frankly rather frightening. I realize that cars are viewed as a necessity, and even a right, here. However, I don't think that everyone should drive. If we took the worst 5% of drivers off the road, whether through stricter licensing standards or more rigorous enforcement, I feel that we could prevent tons of accidents. Cichlidae fucked around with this message at 03:10 on Aug 4, 2009 |
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Aug 4, 2009 02:39
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I've really been enjoying this thread, and feel like I've learned a thing or three. Thanks! I've got my own pet intersection that you might be amused by. This one's in Victoria, BC, and just has the most ridiculous layout (okay, not as bad as some of the nightmares that have been posted, but still goofy). The phasing of the lights always seemed hosed up until I read this thread, and now it makes a bit more senes, but still, there's a little patch of pavement in the middle of the intersection where cars can actually be stopped, while all six other directions speed around them.  http://tinyurl.com/nhr5t8  Is there anything that could be done to make this a less ... broken intersection? The traffic's never as bad as you expect it to be through here, although I'm sure that's more due to people just avoiding it.
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Aug 4, 2009 08:54
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Now, we get a lesson on route choice! Observe: As you can see, we have 2 routes. Route 1 is a bit out of the way, but it can carry a lot of traffic, whereas Route 2 is rather direct, but can't handle as much. Somehow, we figured out that the travel times associated with each route are linear equations that vary directly with the number of cars using them. Obviously, this is a very simplified situation! Now, if you're a car leaving the origin, let's assume you have a pretty good knowledge of what conditions will be like. As a driver, you'll want to choose whichever path will get you to the destination in the least time. Now, if everyone acts to choose the optimal path, we'll minimize delay, right? Well, not quite! It turns out, in order to minimize delay, we need to force some drivers to take a slower route. It seems a little bizarre, I know, so let's look at it mathematically. In the first case, known as user optimal routing, we set the travel time on the two routes equal to each other. However, on the system optimal routing, we need to minimize the total delay. It's some pretty simple algebra and calculus, so have a look! code:1) How do we find out what is optimal in the real world, when we don't know where people are going? 2) How do we convince drivers to take a path that they know will take them longer? 3) Won't this get incredibly complicated once we look at a system with hundreds of potential paths, and whose travel time equations include hundreds of variables? Ladies and gentlemen, this is the future. Someday, somehow, we'll be able to feed motorists efficiently through our routes. Until then... mind the delays.
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Aug 4, 2009 17:34
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Simkin posted:I've really been enjoying this thread, and feel like I've learned a thing or three. Thanks! I gave it a quick go; tell me what you think.  To make a real assessment, I'd need to see the traffic volumes, look at what buildings I'd have to demolish, check out sight lines, etc. The way I arranged it, there's a jughandle (didn't someone wonder where they were used?), and I assume people going between 1A and Government Street can use Rock Bay Ave. If there's really a lot of traffic on Government Street, I'd turn Hillside Ave into a dead-end there and tee up Government Street into 1 directly. In other Canada news, I looked more into fabled route 401 today, and it turns out it's actually the busiest road in the world, carrying 40% of trade between the USA and Canada. On some days, the busiest (18-lane) parts of the freeway see half a million cars! That introduces another fault of the interchanges I reviewed earlier: they just don't have enough through lanes. I couldn't tell this from the aerial photo, but it seems like the lanes are also quite narrow.
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Aug 4, 2009 17:47
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Cichlidae posted:To make a real assessment, I'd need to see the traffic volumes, look at what buildings I'd have to demolish, check out sight lines, etc. Gov't street/Highway 1 sees the heaviest volume, with Hillside secondary to that. The only building that your plan would demolish is a lovely liquor store that sells to meth addicts, so no big loss. quote:The way I arranged it, there's a jughandle (didn't someone wonder where they were used?), and I assume people going between 1A and Government Street can use Rock Bay Ave. If there's really a lot of traffic on Government Street, I'd turn Hillside Ave into a dead-end there and tee up Government Street into 1 directly. Government street is pretty bad for the duration of regular peak volume times, which is just exacerbated by having far too many unprotected lefts across a busy 2-3 lanes of traffic. The really bad (traffic wise) intersections around here aren't even particularly complicated ones, they just happen to be on a route between the city and recent (pooly planned for) maaaaaasive developments.  I do like the way that you tidied that intersection up, though, and hopefully at some time in the future, the city will wise up and bulldoze that whole stupid interchange.
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Aug 4, 2009 20:56
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