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Cichlidae posted:SCATS is highly looked upon by ITS professionals. However, at least in Connecticut, we don't have anything that comes close. To be fair, though, we don't have even block lengths anywhere, which is where a system like SCATS would see the most benefit. Are all lights standalone in Connecticut? Baronjutter posted:What do the squiggly consummate-v lines on the roads mean? It's meant to mean slow down, and it's not used anywhere else in the state of Victoria. Silly VicRoads
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Jan 19, 2012 02:59
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Mandalay posted:slow down He. Asked. What. Those. Squiggly. Lines. Meant. 
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Jan 19, 2012 03:13
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DogGunn posted:Are all lights standalone in Connecticut? Most are isolated, but a decent fraction are on coordinated systems. They often run with an even higher delay, because they're not adaptive in the least. A small fraction of state signals (but a good portion of signals in cities) are on closed loop systems, where the whole thing can be controlled from a central area. They don't have nearly enough system detectors to provide for an adaptive system, though. Our loops break constantly because of the plows and freeze/thaw cycles.
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Jan 19, 2012 03:31
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Didn't New Haven just put in some fancy system that replaced all the lights and added cameras (that they swear aren't for red-light tickets) on them?
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Jan 19, 2012 03:34
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smackfu posted:Didn't New Haven just put in some fancy system that replaced all the lights and added cameras (that they swear aren't for red-light tickets) on them? Yes, that's a closed-loop system. I'm not sure how sophisticated it is. If it's like Hartford's, then it's basically one huge coordinated system with a central controller. Someone in the office can look at each signal, put in calls, change timings, and all that. New Haven is blessed with a relatively regular block system, so they might have something a bit more advanced. I worked a tiny bit on that project, but it's not in my district, so I don't know much else. What's really infuriating is when we spend millions on a fancy closed-loop system, hook it all up, and then they just disconnect the master and stick it in a closet, leaving all the signals on free operation. (I'm looking at you, Glastonbury...)
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Jan 19, 2012 04:11
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Cichlidae posted:Alternates A, B, C, and "none of the above" I like Alternate C the best, mainly because you were able to eliminate the 180° off-ramp, but I'm concerned about the 91N on-ramp. The way you have it, the cars are accelerating from a stop and joining the fast lane of the 15N-91N off/on-ramp, and then become a middle lane on 91N. How bad is it to have an on-ramp come in from the left? Do they have enough room to accelerate? I see you used another approach in alternate A, but at the cost of building a bridge. What if you had the on-ramp connect directly to 91N and moved the 15N-91N ramp further north? It'd eliminate a bridge, but would having two on-ramps that close together cause other problems? I just saw the I-84
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Jan 19, 2012 05:44
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I just got back from an NYC trip, and I noticed that CT seems to take much better care of its section of I-684 than New York does. Good job! Also, do you guys have a fetish for "No turn on red" or something? It's worse than MA there.
Airconswitch fucked around with this message at 06:17 on Jan 19, 2012 |
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Jan 19, 2012 06:06
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Bow TIE Fighter posted:I like Alternate C the best, mainly because you were able to eliminate the 180° off-ramp, but I'm concerned about the 91N on-ramp. The way you have it, the cars are accelerating from a stop and joining the fast lane of the 15N-91N off/on-ramp, and then become a middle lane on 91N. How bad is it to have an on-ramp come in from the left? Do they have enough room to accelerate? I see you used another approach in alternate A, but at the cost of building a bridge. What if you had the on-ramp connect directly to 91N and moved the 15N-91N ramp further north? It'd eliminate a bridge, but would having two on-ramps that close together cause other problems? If I moved the ramp from 15, I'd probably push it further south, which would avoid a new structure. I like keeping all the on-ramps together, but it's not really essential. quote:I just saw the I-84 Sure, give it a shot. That thing was built for another interstate that never panned out, so I'm sure there are improvements to be had. Airconswitch posted:I just got back from an NYC trip, and I noticed that CT seems to take much better care of its section of I-684 than New York does. Joke's on you, New York maintains that section! We have a maintenance agreement with them. I don't know why they take better care of the CT section, though. quote:Also, do you guys have a fetish for "No turn on red" or something? It's worse than MA there. We used to have a policy that mandated NTOR pretty much anywhere near a school, or anywhere else there was decent pedestrian activity. That's no longer the case, but we haven't been going around removing needless NTOR signs, either.
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Jan 19, 2012 13:28
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The most frustrating interchange near my place is one that doesn't exist--there's simply no direct link (without local streets) between I-5 and CA-261: http://maps.google.com/?ll=33.717946,-117.792422&spn=0.005452,0.006534&t=h&z=18&vpsrc=6 I think the traffic volumes justify an interchange but am having trouble googling up any information that would support this point. How would you design it? The toll road was planned before many of the surrounding businesses were built..
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Jan 19, 2012 20:40
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Mandalay posted:The most frustrating interchange near my place is one that doesn't exist--there's simply no direct link (without local streets) between I-5 and CA-261: http://maps.google.com/?ll=33.717946,-117.792422&spn=0.005452,0.006534&t=h&z=18&vpsrc=6 I don't see any way to build an interchange there without demolishing tens of millions of dollars worth of property. The nearby interchange to the north complicates matters further, as interchanges should (ideally) be 1 mile apart, so either you're looking at C-D roads (and all-new bridges up and down the stretch), or a quadrant interchange cutting a huge swath out of the urban landscape.
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Jan 20, 2012 04:14
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That is a clusterfuck. I wonder how some of that land between the on-ramp and the expressways was ever sold. The state should have bought it when it was building the interstate and held onto it before anything was ever built there.
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Jan 20, 2012 15:27
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I don't know if this was pasted somewhere previously in the thread, but while we're on the subject of interchanges there's a great one near where I live, the Somerville Circle, also known colloquially as "The Circle of Death" http://maps.google.com/maps?q=Somer...Jersey&t=h&z=18 202 and 206 are very heavily used roads, so this is always a fun interchange anytime there's traffic, and the road on the circle isn't maintained as well as it should be so you MAY slide a bit on the west end of the circle going under the overpass  .There's a stoplight next to the TGI Fridays that determines whether the offramp or the exit gets to proceed, and the red cycle is the only chance for traffic stopped at the stop sign in the circle has to really get out and proceed. There's a red light down past Fresh Food Kitchen that controls entry into the circle, but it doesn't really seem to affect things very much aside from preventing gridlock on the south east side of that circle just before the stop sign. How would you suggest changing this to not make me take my life into my own hands as I drive through? As a note, the structure just southwest of the circle closest to it is condemned and slated for demolition, so that's cheap. But don't you dare touch Fresh Food Kitchen, it's healthy fast food and they play classical music <  >
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Jan 20, 2012 19:51
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Over here in London, the Hammersmith Flyover (link) was suddenly shut completely because someone noticed that it was falling apart: It's maybe the single most important route into central London, letting traffic avoid a heavily congested roundabout below, along with the centre of Hammersmith and its bus station, tube stations and shopping centre. It's been around since the 1960s and apparently no one bothered to properly have a look at it for the past 50 years. There was a whistleblower who alerted Transport for London that there may be a problem. They denied it, then checked for themselves a few days later and immediately closed it on the 23rd of December to all traffic, right in time for Christmas.  The problem appeared to be that the past few years of (relatively) harsh winters meant that extra salt laid down helped to corrode the cables. Recently they decided to reopen 1 lane on the edge of the bridge to light traffic only, but it look like the situation will remain this way for months. Maybe years if the entire thing has to be replaced. They promise it will be fixed for the Olypmics though (this is the route from Heathrow Airport so this is quite an issue). nozz fucked around with this message at 20:07 on Jan 20, 2012 |
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Jan 20, 2012 20:04
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Volmarias posted:Somerville Circle Jesus Christ, I hate the Somerville Circle. 206 is a good cutoff from the Philly area to upstate New York, rather than the added tolls and mileage from staying on the turnpikes, but the downside is you have to drive through that mess. I've only been through it a few times, but every time I've been going south, it's been a memorably confusing and harrowing experience.
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Jan 20, 2012 20:19
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Volmarias posted:I don't know if this was pasted somewhere previously in the thread, but while we're on the subject of interchanges there's a great one near where I live, the Somerville Circle, also known colloquially as "The Circle of Death" Easy! I can re-use the existing structures and require only minor widening.  Alternatively, with some structural work, you could do the same thing with a SPUI instead of a diamond. The real trick is setting up good access management so you don't have commercial driveways on your ramps. noblergt posted:Over here in London, the Hammersmith Flyover (link) was suddenly shut completely because someone noticed that it was falling apart: I'm REALLY glad someone caught that. Who knows how many structures are in bad shape with no hope of being spotted? There is one tunnel in Fall River, Massachusetts that, it turns out, hadn't been inspected because the City and the State each thought the other was doing it. Lo and behold, the ceiling panels rotted and fell, crushing someone below on I-195. I think scenes like this are going to become much more common in the coming decade.
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Jan 21, 2012 16:31
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Dominus Vobiscum posted:Jesus Christ, I hate the Somerville Circle. 206 is a good cutoff from the Philly area to upstate New York, rather than the added tolls and mileage from staying on the turnpikes, but the downside is you have to drive through that mess. I've only been through it a few times, but every time I've been going south, it's been a memorably confusing and harrowing experience. By "That Mess" I assume you mean 206 because I will go out of my way to avoid that road south of it merging into 202/206. And god help you when you get near Princeton. Cichlidae posted:Alternatively, with some structural work, you could do the same thing with a SPUI instead of a diamond. Yeah, a spui would probably work just fine there. One thing that you can't really on the map is a little prefab building in the center of that circle with electrical boxes near it; I suspect that it's used by the DOT for some signal control things but I have no idea what, so moving the roads may be more expensive than you'd expect.
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Jan 22, 2012 15:16
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Consider the following interchange/giant clusterfuck: http://g.co/maps/25hmu A short onramp (and the turn from Charleston onto 101 is sharper than it looks on the map), a short merge, and for the poor souls coming down 101 southbound, a short offramp which may or may not have someone going 30 miles an hour come out of nowhere trying to get on at the same time. I'm honestly surprised there aren't a ton of accidents here. My question is this: why not just block off the path from Charleston directly? Traffic trying to get to 101 could just take a right instead.
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Jan 23, 2012 03:04
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Incoherence posted:Consider the following interchange/giant clusterfuck: http://g.co/maps/25hmu I'm betting it's because the existing on-ramp is already at/over capacity. It's got two (three?) lanes merging onto the freeway in the space of about 200 feet, which is a LOT of traffic to dump on without a lane add. Our policy in CT is not to build any new on-ramps with two lanes feeding them, because it hurts the freeway LOS badly. Now whether leaving the second on-ramp open is an adequate solution to this problem is certainly up for debate. No-build is very attractive to engineers, not just because of costs, bur because if you start mucking with a substandard situation, you're compelled to fix the whole thing, which would mean completely redesigning the interchange.
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Jan 23, 2012 03:51
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Neutrino posted:That is a clusterfuck. I wonder how some of that land between the on-ramp and the expressways was ever sold. The state should have bought it when it was building the interstate and held onto it before anything was ever built there. That development predates the toll road (but not 5) by probably several decades. 261 is a fairly new road.
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Jan 23, 2012 06:00
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nm posted:That development predates the toll road (but not 5) by probably several decades. 261 is a fairly new road. The Irvine side of the Marketplace, Kia Motors HQ, and a few other pieces were developed after CA-261 broke ground IIRC.
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Jan 23, 2012 08:09
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Also I reckon I-5 can't handle more traffic as-is. Another freeway dumping cars onto the 5 would make things worse.
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Jan 23, 2012 13:50
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So here's an unusually poo poo intersection in AZ. City of Gilbert engineers can bite my rear end for this crap. Google Maps link  It's hard to see in the street view, and the signal head shown seems out of date, but when approaching this combined intersection heading westbound and wanting to turn left, you stop at the near signal. In a single left turn lane. With a left-on-green-arrow-only signal, despite complete unobstructed views for a mile ahead of the empty road. With a no-turn-on-red sign, despite no right turn being available at the near stoplight. One is available at the far light, but no NTOR! Oh, and no U-turn, when there are three lanes of through traffic in each direction. Looking at Street View, it looks like it used to be a protected left with permissive lefts afterwards. Why did they get rid of it?
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Jan 27, 2012 01:25
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IOwnCalculus posted:So here's an unusually poo poo intersection in AZ. City of Gilbert engineers can bite my rear end for this crap. Bizarrely enough, while we spent the last 50 years teeing up intersections, there's a growing movement to split 4-way intersections into two T-intersections. It works better than a single intersection, provided there's not much traffic going between the two side streets. Basically, there are fewer conflict points (9X2 vs. 32) and the signals can operate efficiently with three phases. The NTOR sign basically assumes that people treat the whole thing as one intersection, and it's to prevent them from creeping through the first signal and pulling a right. Not that the people who would be dumb enough to do that would pay attention to a sign, but hey, gotta cover your rear end. quote:Looking at Street View, it looks like it used to be a protected left with permissive lefts afterwards. Why did they get rid of it? It would certainly be protected-only here. It's a decision based on many factors, and there is some wiggle room, but essentially, if it's crossing two or more lanes, protected-only is much better. 
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Jan 27, 2012 03:19
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Cichlidae posted:It would certainly be protected-only here. It's a decision based on many factors, and there is some wiggle room, but essentially, if it's crossing two or more lanes, protected-only is much better.  stop coddling drivers
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Jan 27, 2012 04:11
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Mandalay posted:
It costs about $4 million for each fatality, and tens to hundreds of thousands for any significant accident. Protected-permitted phasing might result in an extra two significant accidents per year compared to protected-only, and they'll likely be severe, as they'll be head-on or t-bone. The exact number depends on many factors, so that's just an educated guess. That's about $200k a year, give or take, versus the 2 passenger-minutes per cycle saved by allowing permissive lefts. It's all a balancing act of safety vs. capacity. You could solve the problem more effectively by getting all the lousy drivers off the road, but I don't think that will happen.
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Jan 27, 2012 04:46
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Cichlidae posted:You could solve the problem more effectively by getting all the lousy drivers off the road
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Jan 27, 2012 04:56
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grover posted:I like this plan. Make it so. An oil embargo would be a good start, or we could brute-force it by dropping concrete barriers in front of every driveway.
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Jan 27, 2012 05:04
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Cichlidae posted:It would certainly be protected-only here. It's a decision based on many factors, and there is some wiggle room, but essentially, if it's crossing two or more lanes, protected-only is much better.  By that logic, almost every left turn at every intersection in the metro Phoenix area should be protected-only. Protected-permissive is on almost every intersection here where there's only one left turn lane, and most lighted intersections here are four-ways between two arterials. Almost anything counting as an arterial is at least two lanes in each direction, and many are three...I can think of at least a couple spots where there are four.They actually just recently completed a project on one of the freeway overpasses nearby my place to change the two left signals for traffic getting onto the freeway - green/yellow arrow and red ball for protected left, then flashing yellow arrow for permissive left. Edit: Clearly they follow that flowchart since every other intersection I can think of with protected-only lefts meets at least one of those criteria. I do still find it amusing how certain intersections just seem to be accident magnets. The one next to where I grew up is still to this day a major crash magnet, despite all four approaches being straight, level, and easy to see, but it probably gets twice as many wrecks as any of the intersections one mile away. IOwnCalculus fucked around with this message at 06:03 on Jan 27, 2012 |
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Jan 27, 2012 05:58
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Cichlidae posted:we could brute-force it by dropping concrete barriers in front of every driveway. I'm pretty sure this would result in only lousy drivers being on the road.
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Jan 27, 2012 07:26
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That's alright, they'll wipe each other out until eventually we end up with the highlander of bad driving. The Idiot King. Able to wipe out entire highways in a single merge.
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Jan 27, 2012 07:47
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Cichlidae posted:It costs about $4 million for each fatality, and tens to hundreds of thousands for any significant accident. Protected-permitted phasing might result in an extra two significant accidents per year compared to protected-only, and they'll likely be severe, as they'll be head-on or t-bone. The exact number depends on many factors, so that's just an educated guess. Those dollar figures are  e: Occupy Intersections, make them all roundabouts
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Jan 27, 2012 18:39
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Mandalay posted:e: Occupy Intersections, make them all roundabouts Turbo roundabouts! The most leftist of roundabouts.
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Jan 27, 2012 19:41
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Koesj posted:Turbo roundabouts! The most leftist of roundabouts. I want to get fantastically rich just so I can buy my own town and fill it with roundabouts, trams, and mixed-use developments. 
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Jan 27, 2012 19:52
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Koesj posted:Turbo roundabouts! The most leftist of roundabouts. I love the smug feeling you get as a Brit when reading these things. "Oh, that sounds cool, I wonder what that is...oh, we already have that everywhere. Right."
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Jan 27, 2012 19:53
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Jonnty posted:I love the smug feeling you get as a Brit when reading these things. "Oh, that sounds cool, I wonder what that is...oh, we already have that everywhere. Right." Dude I used to be able to bike down to the airport and fly to London inside an hour  UK Motorway signage is poo poo though.
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Jan 27, 2012 21:03
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Koesj posted:Dude I used to be able to bike down to the airport and fly to London inside an hour I've always thought it's pretty good, in the sense that a bunch of people sat down in the 60s and went "right, how do we do this properly" and seemed to do a pretty good job, rather than letting it evolve and half-standardise or whatever. What do you mean? I suppose I don't get a full experience of them cos I live in Edinburgh and don't have much cause to go to Glasgow or the south where motorways have more lanes and signs and complicated junctions and things.
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Jan 27, 2012 21:13
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Mandalay posted:Those dollar figures are Yeah, no kidding! That's how we justify spending tens of millions on guard rail improvements. Heck, even rumble strips have a 50:1 benefit:cost ratio. SO! I had some free time, and did a little work in  VISSIM. The latest version doesn't delete things by clicking on them. Progress! Still can't copy or paste anything, though, and no undo.     ...    
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Jan 27, 2012 22:57
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Cichlidae posted:Can you... can you fill it with cars?
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Jan 28, 2012 00:22
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Cichlidae posted:Yeah, no kidding! That's how we justify spending tens of millions on guard rail improvements. Heck, even rumble strips have a 50:1 benefit:cost ratio.  Holy hell man. Exactly how long did this take?And how well does traffic flow on it, I must know...
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Jan 28, 2012 00:25
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THE That's beautiful.
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Jan 28, 2012 01:20
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