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Hey cichlidae, do you have any updates on what is happening with the whole busway saga? I could be wrong, but wasn't construction supposed to start in "the spring"?
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Mar 17, 2012 09:37
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porkfriedrice posted:Hey cichlidae, do you have any updates on what is happening with the whole busway saga? I could be wrong, but wasn't construction supposed to start in "the spring"? Yes, but significant parts of the design are still in the preliminary stages. We'll be issuing change orders weekly (at significant extra cost), and the Amtrak force account still hasn't been figured out, so we have no idea how much money they'll ask for. Those guys have us by the balls, so I'm sure it won't be cheap. On top of it, the contractors will be making a fortune since all of the change orders are no-bid.
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Mar 17, 2012 15:31
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At least the Parkway lane widening and East Rocks Road bridge replacement make driving there much more pleasant. At least something is going well.
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Mar 18, 2012 01:01
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GWBBQ posted:At least the Parkway lane widening and East Rocks Road bridge replacement make driving there much more pleasant. At least something is going well. Hehehehe... you're not going to like what I have to say  First off! The Heroes Tunnel is going to get re-done soon. That means one lane in each direction on the Parkway for... several years I think? Have fun with that. Second, and this is the big one, the Route 34 relocation project that the City has been pushing? Yeah, I've been running the numbers over and over, and that is MASSIVELY going to gently caress up I-91 and I-95. We're talking 6 hours a day, ten-mile-long queues into New Haven. I-91 SB is the worst, since it only has a single lane onto 34 and that carries over 2200 vehicles per hour. In VISSIM, 91 gridlocks to the Route 80 exit in 40 minutes, and that's assuming that we're starting from scratch, roads completely empty. This is a PERMANENT condition, and it will only get worse with time. So why is it happening? Because the City of New Haven has repeatedly told us that they don't give a gently caress about traffic on the freeways, they just want their local roads to look good. Yeah, when all the interchanges are backed up, I'm sure your roads will be great, guys. Also, the City is expecting a huge development to come in where the freeway was, so they're salivating over that. On top of that, this project is all federal money, and if it doesn't go through, the City loses all their planning money, of which they've already promised millions. That means their consultant is telling some pretty blatant lies to try to get this approved. gently caress, sometimes I hate my job.
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Mar 18, 2012 01:58
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Is that only for the end stage of that plan, where 34 is a surface street with intersections?
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Mar 18, 2012 04:00
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smackfu posted:Is that only for the end stage of that plan, where 34 is a surface street with intersections? Yup. Specifically, it only has three through lanes for a volume of 5000 cars in the peak hour. We tried out a few different scenarios to see what would make it work. The signals need to have 7 through lanes to work, and even then, the 4-lane weave with a left exit to the parking garage means huge back-ups.
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Mar 18, 2012 05:09
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I commute from Fairfield to Stamford, so none of that concerns me 
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Mar 18, 2012 16:02
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GWBBQ posted:I commute from Fairfield to Stamford, so none of that concerns me There is a single light of traffic engineering, and to brighten it anywhere is to brighten it everywhere.
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Mar 18, 2012 18:41
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Cichlidae posted:Yup. Specifically, it only has three through lanes for a volume of 5000 cars in the peak hour. We tried out a few different scenarios to see what would make it work. The signals need to have 7 through lanes to work, and even then, the 4-lane weave with a left exit to the parking garage means huge back-ups.
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Mar 19, 2012 16:44
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smackfu posted:Interesting stuff. So does that mean that TIGER grant went through with no traffic studies beforehand? That seems silly. The traffic studies were falsified to show a minimal impact. Edit: Are currently being falsified, in fact. I'm trying to show how far off the mark they are, as the whole of Traffic Engineering is pulling its collective hair out, but New Haven is so busy drooling over the prospect of the developer's money that there's really no chance of the project being stopped. Cichlidae fucked around with this message at 22:52 on Mar 19, 2012 |
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Mar 19, 2012 21:52
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Kansas City suburbs are talking about building a bike trail into Downtown. Interesting factoid: KC Star posted:For a time, the route was even listed in Guinness World Records for having the world’s longest continuous sidewalk. Story here
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Mar 20, 2012 02:22
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Cichlidae posted:The traffic studies were falsified to show a minimal impact. If there is any illegal or at least unethical conduct, isn't there an applicable federal whistle-blowing hotline or something? This sounds bad.
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Mar 20, 2012 04:10
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Wedesdo posted:If there is any illegal or at least unethical conduct, isn't there an applicable federal whistle-blowing hotline or something? This sounds bad. The government's current MO seems to be "Snitches get stitches" so I'm not sure how much good it would do.
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Mar 20, 2012 04:55
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Wedesdo posted:If there is any illegal or at least unethical conduct, isn't there an applicable federal whistle-blowing hotline or something? This sounds bad. The state licensing board would certainly have reason to revoke their PE license. The issue is, I can prove that the modeler has performed unethically, but I don't know whether she has a PE. Her bosses certainly do, but they could claim ignorance. I haven't heard of anyone inside the DOT ever whistleblowing; it's just not done. Doesn't mean it's impossible, though.
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Mar 20, 2012 12:30
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Cichlidae posted:The state licensing board would certainly have reason to revoke their PE license. The issue is, I can prove that the modeler has performed unethically, but I don't know whether she has a PE. Her bosses certainly do, but they could claim ignorance. It's happened a couple times in Florida. I work for a consultancy that does business there and some of our senior engineers who used to be DOT employees have some pretty amazing stories of graft, corruption, and malfeasance.
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Mar 20, 2012 19:54
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Does the simulation power in the new SimCity game come even close to what's being done under the hood in vissim et al? http://www.youtube.com/watch?feature=player_embedded&v=vS0qURl_JJY
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Mar 21, 2012 01:51
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Mandalay posted:Does the simulation power in the new SimCity game come even close to what's being done under the hood in vissim et al? http://www.youtube.com/watch?feature=player_embedded&v=vS0qURl_JJY Oh my god! A new SimCity is in the works? I had no idea! VISSIM's computing power is almost entirely used for driver behavior modeling and output. Its driver behavior model analyzes each vehicle at each time slice (1/5 second by default, up to 1/10 second possible) and goes through thousands of equations based on proximity to multiple other cars, merging (and sympathetic merging), speed restrictions, signals, driver inattentiveness, and route. That's a ton of computing power once you've got ten thousand cars in your network, being analyzed multiple times per second. If you could push those tasks onto the GPU, you could easily speed things up, as it's massively parallel. Its rendering engine is probably ancient and mostly software-based, so that takes a pretty hefty overhead. You can tell just by scrolling around in the program. Running a simulation while zoomed in on a one-foot-square area will run it much faster than zoomed out, regardless of whether you're actually looking at a road. This is on a machine with a modern GPU, and PTV Vision says they use the "latest OpenGL." I'm doubtful. SimCity, on the other hand, has very simple driver behavior. Their route choice seems to occur at the beginning of a trip, probably based on a simple optimization algorithm, and they hardly interact with other cars outside collision avoidance. Their time step can be much longer (1 second or more) since they move slowly relatively to the network and don't have to think far in advance. The rendering tasks in SimCity are much more complex than in VISSIM, but it's running on an engine optimized for such tasks. Probably much more GPU-heavy, but it can offer things that VISSIM can't touch, like textures, anti-aliasing, mipmapping, shaders, and tesselation. Of course, until I get to install it on my work computer, I won't get to see how they compare side-to-side. I have an HD 5870 EyeFinity6 2GB and a Core i7 2600K here, compared to some low-profile G92 derivative and a first-gen Core i3 at work.
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Mar 21, 2012 03:09
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I assume stuff like this happens all the time, right? http://www.therecord.com/news/local/article/690392--homer-watson-roundabout-reduced-to-two-lanes quote:Homer Watson roundabout reduced to two lanes
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Mar 21, 2012 04:27
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EngineerJoe posted:I assume stuff like this happens all the time, right? quote:It will cost $200,000 to reinstall the third lane if politicians resurrect it. Which they will. Couldn't you just drop some jersey barriers to block off the 3rd lane, or better yet paint some thick yellow lines with nice stripey bits to mark it as "don't use, shoulder space" or something? Seems cheaper and better in the long run.
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Mar 21, 2012 13:17
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Multilane uncontrolled conventional roundabouts are stupid anyway.
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Mar 21, 2012 14:33
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EngineerJoe posted:I assume stuff like this happens all the time, right? Constantly. We're going to be taking down some freeway signs because some lady called in to complain that she could see them from her house.  The freeway's been there for 80 years! I guess the burden of catching an occasional glance of green aluminum was simply too much to bear. Koesj posted:Multilane uncontrolled conventional roundabouts are stupid anyway. Yes, that exiting conflict is a real bitch, though they still have similar safety benefits to a one-lane roundabout, believe it or not. Personally, I prefer turbo roundabouts.
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Mar 21, 2012 22:53
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Koesj posted:Multilane uncontrolled conventional roundabouts are stupid anyway. Yeah. Even a 2 lane roundabout is so much more difficult to navigate than a single lane or turbo roundabout. If there was a 3 lane roundabout anywhere around here i'd probably avoid it. In busy traffic it can be very difficult if not impossible to merge back in to the outer lane once you take the inside lane.
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Mar 22, 2012 08:36
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Cichlidae posted:*Whining old people and turbo roundabouts.* Every time they try to stick a new roundabout in my town people freak out (I think I've mention this before; at least it's fewer and fewer whiners each time now). The most recent one was a turbo roundabout and I love the drat thing. The configuration used to be a T-shaped three-way stop, with one of the legs having another road joining it (with another stop sign) just before the 3-way stop (like, fifteen feet before). It was a stupid layout, obnoxious to drive through, and backed up on all four legs any time there was even moderate traffic (waits between 20 seconds to a minute or more to get through). To put it simply, it was shittastically terrible. The new roundabout got rid of all four stop signs, and 95% of the time I don't have to wait at all to drive through it (the other 5% is always less than a fifteen second wait. I've never waited longer than that). However, this particular intersection happened to be in Montecito - which, in case you haven't heard of it, is one of the wealthiest areas in the country, full of celebrities (surprisingly not as obnoxious as you'd think, most of the time) and thousands of other very rich and relatively old conservatives. The any-taxes-are-too-much-taxes kind of conservatives. So when CalTrans came in and said "We're redoing the freeway onramps here along with all the associated intersections, enjoy this new roundabout!" it turned into a steaming pile of loving government look at it wasting our tax dollars on this absurd thing that is so obviously going to be lovely controversy. Good god, was Montecito in an uproar. Here is the web page against that new roundabout on the website one of the main opponents (they oppose just about anything new. Different is bad, mm'kay?). Now, this new roundabout has clearly been a resounding success, so I'm tempted to email them and ask them what they have to say about it now, but they've got their heads so far up their own asses I don't think they can see reality anymore. Check out this page they have about our Milpas roundabout (another turbo roundabout put in at the east side of Santa Barbara maybe seven years ago). That intersection used to be controlled by a signal and had to deal with Milpas Street (2 lanes in each direction), Carpinteria Street coming in perpendicular to that, the freeway offramp coming in diagonally next to Carpinteria Street, and the freeway onramp almost directly opposite Carpinteria Street. It was a minor clusterfuck that often backed traffic up most of a block on Milpas (on bad days, through to the next block), and 5-10+ cars on the freeway offramp while everyone waited for one signal or another. Needless to say, there's almost never a backup with this roundabout, and when there is you get through far more quickly than when waiting at a light. Watch their YouTube video of the OMFG TERRIBLE WAIT they had at the end of the freeway offramp/entrance to the roundabout. Seven seconds! Holy hell! Note that the video even calls that "worse than the stop light the roundabout replaced" -- despite the fact that any braindead moron could see that's a lie when compared to a red light of any duration (it might have been faster if you happened to hit the green light... which was rare, because the heavy Milpas traffic got the longest green by far). This poo poo is so transparently stupid, it's downright hilarious. And then there's the awesome accident statistics with no citations and not-so-subtle racism. Thank god most everyone is learning to ignore these stupid bastards. The problem is they're so drat loudly vocal compared to everyone else...
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Mar 22, 2012 12:16
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Choadmaster posted:Every time they try to stick a new roundabout in my town people freak out (I think I've mention this before; at least it's fewer and fewer whiners each time now). The most recent one was a turbo roundabout and I love the drat thing. Hahaha, look at this poo poo! That Website posted:The Caltrans illustration below Right shows the proposed roundabout at Hot Springs Road that will replace the simple stop sign intersection. The tailgating traffic on the freeway is realistic, but the drawing shows 7 vehicles near the roundabout, where a recent satellite image during mid day shows 11 vehicles in the same area. (Click to view.) I'd love to say we don't have problems with stupid people here, but clearly that's not the case. That's what public informational meetings are for. We invite the media, address every concern (even if it's with "I don't know, I'll get back to you"), and I've actually been trained to ask questions that make prejudice very obvious, which destroys their credibility.  If you build a roundabout, we're going to get the wrong kind of people in town! What kind of people, exactly? You know what kind of people I mean. The fuckin' queers...You need to bring their concerns out in the open, look into the underlying issues, and solve what problems you can without jeopardizing the project. At least that's what we're taught to do.
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Mar 22, 2012 12:36
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Cichlidae posted:Some of our older projects have metric baselines still, but most of them run on 100-foot stations. We also have a coordinate grid that starts somewhere near Pennsylvania and counts up in feet north and east, so the grid coordinates are up near a million. Not too convenient. This quote is ridiculously old, but I'm quite intrigued. Tell me more about this grid. What do you use it for (and is it important that it's highly accurate? How do you deal with the curvature of the Earth?
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Mar 22, 2012 15:44
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Cichlidae, I'm working on a fun project to design a sort of "model town" on a plot of farmland next to the highway as a general exercise in urbanism. Currently along the edge of the plot there is a slightly winding but mostly straight highway with a traffic light and a small 4-way intersection with right turn lanes. The highway is a fairly standard 80kmph 2 lane (about 32m wide) each way at-grade highway while the road crossing it is a 11m wide 2 lane country road. The highway runs north/south and the road runs east/west. Farms and rural homes lay to the west, and the fantasy town will be east so that will be where the majority of traffic comes from. Traffic should be coming and going fairly evenly both north and south. What would be the best way to handle this? It's all fields around the intersection so space isn't really a big issue. Obviously we'd like to eliminate the light on the highway but it's totally fine to have a light on the access road. Personally I was thinking of having a simple overpass with 4 ramps running parallel to the highway leading to 2 signaled intersections above. but maybe some sort of crazy round-about might work too? PS Sometimes big logging trucks use this intersection, which may be a problem for round-abouts, or at least would require a larger radius circle? Baronjutter fucked around with this message at 17:57 on Mar 22, 2012 |
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Mar 22, 2012 17:47
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Baronjutter posted:PS I'm going to chime in here to say that it's not so much the size of the circle that matters when it comes to large vehicles, but what's in the center and on the outside. Professional truckers know how to navigate tight spaces and will ride up on curbs if they need to. As long as the entrances and exits are wide/gradual enough and you don't place objects on the inside and outside of the circle that could prevent them from getting through safely (IE concrete curb inlets inside the roundabout curb, a giant decorative planter in the center, Jersey barriers, etc.), a standard roundabout shouldn't need to be wider in circumference to compensate for the presence of large trucks. Increasing the diameter of the circle certainly couldn't hurt, but it might be an unneeded increase in the cost of construction. Ideally, the approach just needs to be wide enough so that they can line up an appropriate turn when entering, with the center containing either a painted asphalt or concrete apron with rumblestrip that they can just drive over if needed. That said, if you design something THIS small lined by trees, nothing longer than 35ft can safely use it:  Our resident traffic genius can explain the finer points if needed. Edit: Here's an example of a truck-route roundabout recently constructed in Tampa, FL and its angular cousin a few blocks down the road. The major street is a 4-lane truck route with a design speed of 40 MPH (40th St.), intersecting 25MPH urban roads (Yukon St. and Riverhills Dr., respectively). Notice how the approaches on the truck route make the route as straight as possible. There's also an escape zone on the inside of the circle, paved with red bricks as a visual aid.  
Varance fucked around with this message at 19:21 on Mar 22, 2012 |
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Mar 22, 2012 18:12
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Dancer posted:This quote is ridiculously old, but I'm quite intrigued. Tell me more about this grid. What do you use it for (and is it important that it's highly accurate? How do you deal with the curvature of the Earth? We use it for our Geographic Information System, which is the base grid upon which we lay out all of our projects. It does need to be very accurate, at least as accurate as our surveying equipment, and as far as I know they do account for the Earth's curvature. For my purposes, though, all I really need to know about it is that if I try to export something to Google Earth, it all ends up clumped in Camden. Baronjutter posted:Cichlidae, I'm working on a fun project to design a sort of "model town" on a plot of farmland next to the highway as a general exercise in urbanism. You've got options! A big question should be, how much do you want to impact traffic on the north-south road? Roundabouts require slow speeds, about 20-30 kph. If you're putting one in on a high-speed road, you should put some gentle, and increasingly sharp, curves in advance in order to force drivers to slow down. A roundabout should handle volume well, regardless of directional split, but it will result in delay for your arterial. A signalized intersection would be our typical treatment for that kind of road, provided it meets the signal warrants. Because of the high speeds, I'd put a left-turn AND a right-turn leg on the two high-speed approaches. The turn lanes should be at least a hundred meters long, not because of queue capacity, but because you want your cars to decelerate within the turn lanes, not before. Arterial detection for the dilemma zone is a must, as well. If there are relatively few turns (25% or less of total entering volume turns), you could use a quadrant interchange. One small bridge, two three-way signals, and pretty good capacity. It just takes up a lot of space. The signal on the minor road could even be replaced by stop control, provided the volumes are low. And then, as you mentioned, a diamond interchange (your idea with one overpass and four ramps) would maximize throughput on the main road and provide a good foundation for future widening. It's just going to be expensive, and might be overkill, depending on the volumes.
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Mar 22, 2012 18:37
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After some additional study, and finding a very similar interchange situation along a similar highway nearby I decided to try 2 round-abouts. So 4 ramps leading to 2 circles with an overpass between them. Sound good?
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Mar 22, 2012 18:49
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Baronjutter posted:After some additional study, and finding a very similar interchange situation along a similar highway nearby I decided to try 2 round-abouts. Be sure to show me how it turns out!
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Mar 22, 2012 19:53
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Cichlidae posted:We use it for our Geographic Information System, which is the base grid upon which we lay out all of our projects. It does need to be very accurate, at least as accurate as our surveying equipment, and as far as I know they do account for the Earth's curvature. I don't think they do, which is why there are individual grids for countries and regions. The curvature of the Earth is small enough then that it's not significant. The Netherlands uses a grid with its origin just north of Paris, so that all coordinates that are actually inside the Netherlands are always positive numbers. I imagine your grid having its origin in Pennsylvania is for the same reason. Cichlidae posted:For my purposes, though, all I really need to know about it is that if I try to export something to Google Earth, it all ends up clumped in Camden. Google Earth uses WGS84, which is not a flat grid but uses degrees/minutes/seconds and spans the globe. If you simply dump data from a flat projection into it (like the Pennsylvania-based grid) then your data won't end up in the right place. You'll need to transform the coordinates, which ArcGIS and other GIS software can probably do. Apologies if you already know all this, I'm far from an expert on projections but GIS is my job. What I do mostly is processing our surveyors' measurements of newly completed or altered bits of highway. Me and my collegues then process the measurements into a complete database ready to send to the highway authority. They then integrate it into their main database that covers all highways in the country. That database contains almost every object belonging to the highway authority, including the pavement, lamp posts, guard rails, pavement markings, traffic signs, sewer pipes, traffic lights, distance markers (every 100 meters), as well as all the underground cables to power and control everything, all in x, y and z coordinates. Then there's the attribute data for every object, specifying its exact type (what kind of traffic sign, which type of lamp) as well as information like when the object was installed (if known), and which district it belongs to. It's pretty comprehensive as well as a pain in the rear end to fill in everything completely and correctly, and the highway authority is pretty good in spotting any omissions or errors when we submit the database for a newly completed stretch of highway.
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Mar 23, 2012 00:00
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whats at 0,0,0?
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Mar 23, 2012 00:52
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John Dough posted:I don't think they do, which is why there are individual grids for countries and regions. The curvature of the Earth is small enough then that it's not significant. Our datum is NAD83, and is a State Plane system, according to this website. Elendil004 posted:whats at 0,0,0? Far as I can tell, it's just some point in Pennsylvania. The Z coordinate 0 means mean sea level. 0,0,0 is probably in a sewer.
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Mar 23, 2012 00:59
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Elendil004 posted:whats at 0,0,0? I bet it's where they bury traffic engineers.
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Mar 23, 2012 01:10
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It's in Maryland! http://g.co/maps/k3r48 Source: http://www.earthpoint.us/StatePlane.aspx
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Mar 23, 2012 01:51
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The Proc posted:It's in Maryland! There we go! In the Aberdeen Proving Ground, near some buildings, in the trees... 
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Mar 23, 2012 02:14
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Tangentially related the traffic engineering, but I really wish that the roadworks crews that end up working on these things would pay more attention to where they dig. Nothing like straight up killing broadband and tv for large parts of the country because some idiot in a giant machine didn't pay attention to where the fibre runs are laid down. Even better when its just some little company doing some digging for whatever and they end up chewing on that juicy fiber optic cable. Enjoy your $20k+ for getting that spliced together again. At the lower level we also have utilities people (replacing sewer/water pipes, putting power cables into the ground) digging through the regular coax cables. At least the waterworks people have the common courtesy to call and say they hosed up and please send a guy to fix it. The power company usually denies they even had people working there.
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Mar 23, 2012 10:47
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Baronjutter posted:Cichlidae, I'm working on a fun project to design a sort of "model town" on a plot of farmland next to the highway as a general exercise in urbanism. If the logging trucks are a problem, perhaps this is an option to consider:  (Sorry for the bad quality, it's in a rural area and this is the highest resolution i could get on Google Maps) This is a roundabout near a company that manufactures large pre-stressed concrete beams. The trucks that transport them (http://www.youtube.com/watch?v=lnhgDvDWk6E&feature=related) couldn't turn through a regular roundabout, so they built a bypass in the middle. The bypass is built in such a way that regular cars can't use it.
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Mar 23, 2012 13:23
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How are cars not able to use it?
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Mar 23, 2012 13:59
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Elendil004 posted:How are cars not able to use it? The bypass is built higher than the roundabout. If a car would enter it, the height difference would cause damage to the underside of the car. Trucks can easily clear the difference because they have a larger ground clearance.
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Mar 23, 2012 14:14
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