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Guy Axlerod posted:Seeing as I had to look up what HAWK signals were, I figure someone else might too. I found these two videos to be pretty good: Thanks for those. The concern is that if we've got a pedestrian showing up every 30 seconds at the signal, you either have traffic stopped all the time or people are stuck waiting for the HAWK signal to do something. People hate to wait, so they'll probably try to cross without the signal. Not ideal, although roundabouts do simplify crossing without a signal. From my understanding the signal is dark until someone presses the button. The button makes it go yellow for a while and then red. The dark signal can be confusing, since in most states you're supposed to stop for a blacked out traffic light. None of this would be a big problem most places, because the state has tons of roundabouts in planning and it _will_ become the new norm...but hospital administrators don't like being the guinea pig for new and exciting traffic control technologies. 
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Jan 29, 2010 21:06
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ppdd posted:Question for a roundabout enthusiast! You're not paying me nearly enough to do this for you  From what you've shown me, and the fact that it's LOS D with left turn lanes on all legs and two through lanes on Fuller Road, there are probably at least 1000 through cars and 800 lefts. That kind of volume is too high for a single-lane roundabout. I wouldn't install a two-lane roundabout without considering a turbo roundabout first, and if you don't have any of those around, it'll really confuse people. As to the hybrid ped signals, like Guy Axelrod says, people are pretty confused by them. The FHWA's studies have shown that they work pretty well, but I'm still wary and I know we won't be installing any in Connecticut. There's the potential for confusion with a dead signal, and even when it's working, it's confusing for people who aren't familiar. I hope you aren't considering sending peds through the roundabout, into the center island, because that's a huge no-no. You'd have to push them back across the approaches through the middle of the splitter islands. Of course, peds have a tendency to walk in a straight line, so you will probably have people entering the roundabout anyway if you landscape it to look pretty. A truck apron, incidentally, looks a lot like a sidewalk. So, how to treat this intersection? It's probably too heavily traveled for a roundabout. I'd go for adding more intersections and access roads, but the railroad track would make that very expensive. Sticking more lanes in the signalized intersection, like you said, is only a temporary solution, and you'd need to widen the railroad overpass. A pedestrian bridge is a worthwhile, though costly, solution. It'd also improve the intersection's LOS significantly if peds are as common as you say. Anyway, I love roundabouts, but I really don't think this is the best place for one. Roundabouts are meant for lower traffic volumes, and they don't play as nice with high ped volumes as signalized intersections do. Cichlidae fucked around with this message at 23:01 on Jan 29, 2010 |
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Jan 29, 2010 22:58
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I was going to ask if a Ped Bridge would be warranted here. I know if I were a pedestrian there, I would like seeing it, especially if there were a traffic circle. If were to come up to a circle I'm not sure I'd know the "right" way to cross it. If not a HAWK signal, what would you use at a signalized crosswalk? Or would you avoid the idea entirely? The type I've seen is a flashing yellow in the bottom aspect, with a yellow and red above. The flashing yellow in place of green prevents a dark signal, but is it confusing for some drivers?
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Jan 30, 2010 01:49
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Guy Axlerod posted:I was going to ask if a Ped Bridge would be warranted here. I know if I were a pedestrian there, I would like seeing it, especially if there were a traffic circle. If were to come up to a circle I'm not sure I'd know the "right" way to cross it. Hybrid ped signals are for mid-block crosswalks, not signalized intersections. At signalized locations and roundabouts, I'd put a normal ped head: the lunar white walking man and the portland orange upturned hand. Very simple to understand. Edit: If you're asking what I'd use for mid-block crossings, I like a single yellow face on a pole on each side of the road that flashes for a set time when the button is pressed. The motorist's eye should be on the peds; the signal is just to let him know something's going on.
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Jan 30, 2010 03:24
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Cichlidae posted:Hybrid ped signals are for mid-block crosswalks, not signalized intersections. At signalized locations and roundabouts, I'd put a normal ped head: the lunar white walking man and the portland orange upturned hand. Very simple to understand. Right, I meant: What signals would you provide for the vehicles at a mid-block crosswalk? (It looks like you answered.)
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Jan 30, 2010 04:56
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Guy Axlerod posted:I was going to ask if a Ped Bridge would be warranted here. I know if I were a pedestrian there, I would like seeing it, especially if there were a traffic circle. If were to come up to a circle I'm not sure I'd know the "right" way to cross it. In the Netherlands we would probably have something like this: http://maps.google.com/?ie=UTF8&ll=...2,311.68,,0,8.9 The white bars are ped crossings that drivers are required to stop for. Normally they are a little further away from the roundabout though, to prevent cars from being stopped on the roundabout waiting for peds, or on the crossing waiting for cars on the roundabout. This is at a crossing of two pretty major roads in the city but traffic doesn't look to be all that high. With more traffic, there would be a signalled intersection with pedestrian signals. With even higher traffic they would have tunnels for peds and bikers - I rarely see bridges for them, only when they also need it to look cool or something, like this: http://maps.google.com/?ie=UTF8&ll=...2,101.83,,0,3.6
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Jan 30, 2010 13:44
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Entropist posted:...With even higher traffic they would have tunnels for peds and bikers - I rarely see bridges for them... Ped bridges are considered much more ped-friendly than tunnels here, since tunnels tend to invite violent crime and flood easily. And, like you said, a bridge looks a lot cooler than a tunnel (at least in the US, you have some awesome-looking tunnels in Holland); just have to make sure it doesn't block sight distance.
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Jan 30, 2010 18:06
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What's with the streetlights they put up on the Parkway? Is it just those few around one bridge or are there going to be more?
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Jan 31, 2010 08:11
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Hey. This thread is ridiculously interesting. I live in Rochester, NY. I'm curious if you know of and what you think about our (not)famous Inner Loop. http://maps.google.com/maps?client=...ved=0CAkQ8gEwAA http://en.wikipedia.org/wiki/Inner_Loop_(Rochester) I'm pretty sure it was built originally to make it easy to get around the middle of the city of Rochester. This was a great idea when Rochester was sort of a booming city, but in the past few decades very few people use it as companies aren't moving into the center of Rochester.
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Jan 31, 2010 15:51
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GWBBQ posted:What's with the streetlights they put up on the Parkway? Is it just those few around one bridge or are there going to be more? Not sure; my division doesn't deal with lighting. My impression would be, given the fact that the entire Parkway is designated as historic, light installation will be limited. I do know that it is getting a good chunk of its metal beam rail replaced by Merritt Parkway rail, which is wood beam on metal post. Snazzy. Cybor Tap posted:Hey. This thread is ridiculously interesting. That's cool, it's rare to see a freeway with volumes that have declined so much. The only example I can think of in CT is I-395 between I-95 and CT 695. Looking at it on the aerial photos, it's pretty obvious how outdated and substandard the design is. Lane drops and lane adds all over, weaving sections, short accel lanes, left entrances/exits... Most cities would kill for an inner loop, though, even a poorly operating one like that. Personally, I'd say turn it into an at-grade avenue, possibly with light rail down the middle, if conditions (and budgets) merit. Don't allow developers to encroach. 50 years down the line, Rochester might be in better shape, and they can turn it back into a freeway with relative ease. Of course, there's very little short-term benefit for the city in this proposal, so it's unlikely it'd be done. It would certainly help to link the inner and outer parts of town and reduce maintenance costs, but would cost tens of millions and screw with traffic for months or years.
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Jan 31, 2010 17:11
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If we want to talk about Rochester, we should talk about the can of worms. http://maps.google.com/maps?ll=43.143176,-77.54734&spn=0.01,0.01&t=m&q=43.143176,-77.54734 The intersection of I-490 and I-590. I-590 becomes NY-590 north of the intersection. Also present are East Ave and CSX Rail. It was rebuilt in late 80's and early 90's. This page has some before and after shots: http://www.empirestateroads.com/week/week1.html The original design had much more weaving than there is now. Even after the reconstruction, 590 NB has quite a bit of weaving. Coming from 490 WB to 590 NB you can be forced to get off at Blossom if traffic is heavy enough. (Also you are not aggressive enough.) E: I found an aerial shot of the interchange from before the reconfiguration.  Click here for the full 926x861 image. Notice the weaving on 490 WB/EB. Also notice the rail spur N/S parallel to I-590. Guy Axlerod fucked around with this message at 19:32 on Jan 31, 2010 |
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Jan 31, 2010 19:24
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Guy Axlerod posted:If we want to talk about Rochester, we should talk about the can of worms. That's a very satisfying reconfiguration. Despite the weaving that still exists, it's not a massive problem like it used to be. The old configuration of East Ave and University Ave was just ridiculous. That the new interchange fits in the right-of-way of the old one just shows how gratuitously hosed up highway design standards were 60 years ago.
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Jan 31, 2010 20:02
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Aw that takes me back. I used to live off the first exit going 590N. My parents still live there 2 minutes off Blossom road. Can of worms was hell, apparently. I was never old enough to really remember how bad it was.
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Jan 31, 2010 23:52
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Cichlidae posted:You're not paying me nearly enough to do this for you Thanks for the free advice. That's really incredibly helpful. Reality checks are nice. It'd be a 2 lane (non-turbo) roundabout, but it sounds like we'd be crazy to do this given that we've got about 500 pedestrians and 40 bikes an hour through the intersection at peak. Sounds like people just don't try to mix that many pedestrians with that many cars at roundabouts. We've basically been asked to take it as a matter of faith that the pedestrian component will be fine, because they can't make their software model take into account the peds. Pedestrian bridges have been suggested off and on, and it's the right solution, but since there's no money anywhere in the state right now...sigh. Unfortunately that's the case for anything we do here. And given the topography, railroads and river there's essentially no way to touch anything outside the intersection itself. ppdd fucked around with this message at 22:05 on Feb 1, 2010 |
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Feb 1, 2010 21:52
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ppdd posted:Thanks for the free advice. That's really incredibly helpful. Reality checks are nice. 500 peds an hour is REALLY a lot. I've looked at a signal with 100 peds an hour (at noon, not even in the peak hour!), and luckily, only 8 of those called the ped phase. Ped phases, especially with a hybrid signal, take a very long time (thank Granny McOld for that). If the bikes are using the sidewalks and not the street, they count as peds, too. What software is your consultant using that can't model peds? At least you could put a dummy all-red phase in the signal or a stop sign on every approach to mimic the effect somewhat. I don't know what you'd tell them, though. "Some guy on the internet says your simulation sucks!" Unfortunately, money is always a concern, and you might get stuck with a cheap design that only backs up 4 hours a day instead of 6. If you really want a nice roundabout to act as an entryway to the site, you can give it a shot; it'll act like an all-way stop when it gets congested. Just make sure the peds are accommodated safely; lack of funds is no excuse for unsafe roads.
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Feb 1, 2010 22:50
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After driving around CT this weekend, there should totally be a highway between Waterbury and New Haven. It would save me so much time!
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Feb 1, 2010 23:13
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smackfu posted:After driving around CT this weekend, there should totally be a highway between Waterbury and New Haven. It would save me so much time! Had the Route 10 expressway been built, your trip would be much easier. A short trip up 84 and then down 10 straight to New Haven. Heck, even a more complete Route 34 expressway would've helped you out a lot. You have NIMBY to blame for your current travel times.
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Feb 1, 2010 23:35
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smackfu posted:After driving around CT this weekend, there should totally be a highway between Waterbury and New Haven. It would save me so much time! Since there's no real straight shot, I would probably have just gone down route 8 to 34. It's not a complete straight shot but I would imagine it's not too bad.
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Feb 3, 2010 01:47
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Over here in Indiana I generally praise my local INDOT district. They go a good job at snow removal, keep lines and reflectors on the roads, and won't let the road turn into a jungle of potholes. However, there's been a lot of controversy over a recent decision involving a set of bridges crossing the White River.  Click here for the full 700x532 image. Behold, the Newberry Bridges, currently the two most controversial bridges in Indiana. There are two basically identical bridges. The one in the picture crosses the river, and there is one a little ways behind where the picture was taken that crosses a field that doubles as overflow for the river. Back in December INDOT placed a 14-ton weight limit on both bridges in order to "protect their structural integrity." They have even more recently installed traffic signals on each bridge, cutting it down to one lane of traffic at a time. The same time the signals were activated, they lifted the 14-ton weight limit.  What I don't understand is this: If a 14 ton weight limit was required to preserve their structural integrity, why is it no longer required now that there are traffic signals on the bridges? To me it seems like the traffic signals would increase the weight load on the bridges, because you now have the possibility for 8 loaded coal trucks to back up waiting on a light, and then proceed to cross the bridge in a line. Previously without the signals, it was rare to see more than 1 or 2 vehicles on the bridges at the same time. Granted I'm no engineer, so could someone explain INDOT's logic? Oh and the best part... according to INDOT it will be somewhere in 2013 before construction starts on replacing the bridges. Hopefully they won't fall down before then.
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Feb 4, 2010 02:39
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Maniaman posted:Over here in Indiana I generally praise my local INDOT district. They go a good job at snow removal, keep lines and reflectors on the roads, and won't let the road turn into a jungle of potholes. Bridge designers have to take into account that long queue of cars, whether there's a signal on each end or not. Cutting it down to one lane just means half as much design load. It keeps it in the center of the bridge, which distributes the live load relatively evenly between the two sides. If the bridge keeps getting worse, they'll likely reinstate the 14-ton limit, with a single lane. Hopefully, there will be a temporary bridge during construction. I don't know how far it is to the next crossing, but things are so spread-out there that it might be nigh impossible to do a detour. It could be worse, though! We put up pedestrian detours for every non-freeway job. So if there are any peds that use that bridge, we'd have to find a way to either ferry them across or build a temporary pedestrian bridge! Cichlidae fucked around with this message at 03:13 on Feb 4, 2010 |
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Feb 4, 2010 02:53
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Definitely won't be any pedestrians crossing this bridge. There's a very small town on one side of the river, and then its a good 10 miles probably to the next town. Here's a Google streetview of one of the bridges: http://maps.google.com/maps?f=q&sou...2,16.06,,0,3.08 And here's a map of the area. The bridge in question is by the A marker. http://maps.google.com/maps?f=q&sou...3,0.441513&z=11 If the bridges were closed, the only two detours would be (from the north) via IN-54 and US-231 or IN-67 to IN-58. The road by these bridges was actually closed for a number of months following major flooding in June 2008 that washed out a smaller culvert a few miles north of the bridges. From what I understand, they were originally slated for replacement this year but the historical and environmentalist folks blocked it because they think these bridges are historical or something. Alright, they're the last bridges of this type in the area, but I'd rather see them get replaced than fall down with people on them. On the subject of new construction and demolition, how to they generally dismantle bridges? I would thing it would be easiest to stick some explosives around the main supports and let it fall into the river, but I'm almost sure there is some law that prevents them from dropping a bridge in the river. Not to mention the fact that once its at the bottom of the river it would be fun to get back out. Piece by piece wouldn't really work though as you'd have to drive heavy machinery across it to dismantle the very support beams holding you up. Come 2013 when these bridges begin being dismantled I'm going to have to spend some time around there watching it. Also on the bridge topic.. All of the other bridges in the area were similar to this Newberry Bridge. They have all since been replaced with your standard mostly concrete bridge. My dad swears that if we had a decent earthquake, the concrete bridges would all crumble and fall down, while the old Newberry bridge would survive. Structurally speaking, which bridge would be strongest and most likely to withstand a natural disaster? The newer concrete bridges, or the older mostly steel bridges? Let's assume both bridges were built at the same time right beside each other.
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Feb 4, 2010 04:33
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Maniaman posted:Also on the bridge topic.. All of the other bridges in the area were similar to this Newberry Bridge. They have all since been replaced with your standard mostly concrete bridge. My dad swears that if we had a decent earthquake, the concrete bridges would all crumble and fall down, while the old Newberry bridge would survive. Structurally speaking, which bridge would be strongest and most likely to withstand a natural disaster? The newer concrete bridges, or the older mostly steel bridges? Let's assume both bridges were built at the same time right beside each other.
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Feb 4, 2010 13:15
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Maniaman posted:Definitely won't be any pedestrians crossing this bridge. There's a very small town on one side of the river, and then its a good 10 miles probably to the next town. In this case, we'd just add some architectural elements on the new bridge that are similar to the old one, or build a new bridge alongside and use the old as a ped bridge. If there are no pedestrians, though... quote:On the subject of new construction and demolition, how to they generally dismantle bridges? I would thing it would be easiest to stick some explosives around the main supports and let it fall into the river, but I'm almost sure there is some law that prevents them from dropping a bridge in the river. Not to mention the fact that once its at the bottom of the river it would be fun to get back out. Piece by piece wouldn't really work though as you'd have to drive heavy machinery across it to dismantle the very support beams holding you up. About 70 pounds of plastique (Edit: RDX) will do the job: http://www.youtube.com/watch?v=h2nGtVURPlE It's expensive, though. Cost more to blow up that bridge than it did to build it. quote:Also on the bridge topic.. All of the other bridges in the area were similar to this Newberry Bridge. They have all since been replaced with your standard mostly concrete bridge. My dad swears that if we had a decent earthquake, the concrete bridges would all crumble and fall down, while the old Newberry bridge would survive. Structurally speaking, which bridge would be strongest and most likely to withstand a natural disaster? The newer concrete bridges, or the older mostly steel bridges? Let's assume both bridges were built at the same time right beside each other. I'm not a structural engineer, but I'll answer as best I can. Old bridges were not designed for seismic loads. They had a higher factor of safety, because there was a lot more inconsistency in manufacturing methods, materials, and design. The age of the bridge, though, and the fact that the inspectors put a weight limit and alternating one-way on the bridge, show that it's lost a great deal of its initial structural capacity. Besides that, it was likely built with a non-redundant design, so if one little part breaks, the whole thing will come down. Concrete, despite being brittle, is very strong, and we're required these days to design it to hold up to earthquake loads, and to experience ductile failure when they do break. I'd trust a new concrete bridge over an old, broken steel one. Edit: ^^^ Keep in mind this steel bridge is decades old and already falling apart. I don't think it'd withstand much these days, especially with a queue of vehicles it wasn't designed for traveling across. Cichlidae fucked around with this message at 17:58 on Feb 4, 2010 |
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Feb 4, 2010 13:20
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Cichlidae posted:Cost more to blow up that bridge than it did to build it. Edit: I just looked it up and in real terms it cost twice as much to build as to demolish. Socket Ryanist fucked around with this message at 13:25 on Feb 4, 2010 |
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Feb 4, 2010 13:23
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Socket Ryanist posted:In real or nominal terms? Yeah, not adjusted for inflation. $3M to build, $22M to destroy. RIDOT told me that it would cost more to repaint the Newport Bridge than it cost to build it, as well, though I don't have the figures on hand. I assume that wasn't adjusted for inflation, either. The Jamestown bridge demo was pretty cool. We had a platoon of state troopers halt traffic on each side, since nobody was sure whether debris could hit the new bridge from the old. After the collapse, the DEM was a little pissed off about the fish kill.
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Feb 4, 2010 17:49
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Yeah $3 million in 1940 dollars is over $40 million in 2006 dollars
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Feb 4, 2010 19:57
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Socket Ryanist posted:Yeah $3 million in 1940 dollars is over $40 million in 2006 dollars Yep yep, but it sounds much more impressive without taking inflation into account Heck, we only demolished 2/3 of the bridge. The western third is still up as a fishing pier.Similarly, it only cost about $1 million 1950s dollars to sign the entire Connecticut Turnpike (Greenwich to Killingly). I'll let you calculate the inflation rate now, but we generally assume $3 million per interchange to put up signs these days, times about 90 exits. Of course, that's also a testament to how much heartier our signs are now. The original Connecticut Turnpike signs were small blue ones, not the 40-foot-wide overhead ones we use now.
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Feb 4, 2010 20:57
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Cichlidae posted:They're rather common around here, so I'm very used to them. I assume any stop sign without an "all way" plaque is two-way stop. A traffic engineer can do a lot to make it more apparent when it's only a two-way stop. Big, bold stop bars (and a lack thereof on the cross street), wide shoulders on the high-volume approaches, and signs can go a long way. There used to be a terrible two-way stop just outside my neighborhood growing up. The street with the stop sign, Rundle Rd., was 35mph and intersected with the cross street at the crest of a small hill. Visibility was kind of poor due to the overgrown wooded lot on one corner, and that was made even worse by the fact that the cross street that didn't stop, Eden Park Rd., was 45mph (and this was a small two-lane 100% residential street with a lot of subdivision entrances and quite a few residential driveways directly on the street; I don't even think it had a center line back then. What they were thinking with that speed limit I'll never know...). Both streets had a fair amount of traffic, as everyone in the surrounding subdivisions used one or the other on a daily basis, and there were serious accidents at that intersection all the time. Most usually ended with one or more cars plowing through our subdivision's brick wall and into our neighbor's back yard. Eventually they put up a flashing light, red on Rundle and yellow on Eden Park, but that didn't help the accident rate at all. They finally turned it into a four-way stop after a few more years of regular accidents (and several more rebuilt brick walls). Amusingly, the speed limit on that part of Eden Park is still 45mph, despite the fact that it's a stretch of less than a mile between a very sharp 90-degree curve and a rather dangerous S-curve next to a lake with no shoulder or guardrail (and of course still full of driveways and subdivision intersections), and it's now bisected by a four-way stop.
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Feb 5, 2010 02:09
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Cichlidae posted:Similarly, it only cost about $1 million 1950s dollars to sign the entire Connecticut Turnpike (Greenwich to Killingly). I'll let you calculate the inflation rate now, but we generally assume $3 million per interchange to put up signs these days, times about 90 exits. Of course, that's also a testament to how much heartier our signs are now. The original Connecticut Turnpike signs were small blue ones, not the 40-foot-wide overhead ones we use now. FOR SIGNS? what the gently caress, this is insanity. you have to be able to cut this cost, right? right?
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Feb 5, 2010 02:40
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Mandalay posted:FOR SIGNS? 4 approaching roadways * 3 sign assemblies each (1 mile, 1/2 mile, 1/4 mile) * $250,000 per assembly. That's not counting speed limit, pull-through, gore, confirmation, advisory speed, chevron, camping, hotel, food, gas, service area, alignment, or other directional signs. Most of the cost is the sign support itself, which has a 4 cubic yard concrete foundation on each side and is so large that it can only be hot-dip galvanized at one site in the country. The sign panels themselves run about $10/square foot, but then you still have the poles, vertical attachment members, ASTM F959-compliant load-indicating washers, sign clips, sign panel bolts, reflex reflectors, riveted border, inspection, shipping, labor, and mobilization. The sign panels themselves are either aluminum extruded into a special channel shape then covered in special retroreflective sheeting or sheet aluminum blanks cut to shape with what amounts to a giant pair of scissors with a similar vinyl sheeting. A single sample sheet aluminum sign, which was only .08 inches thick and 4 feet square, still weighed about 20 pounds. Signs in the field are usually 3 times thicker and have rough edges that'll give you a NASTY scrape if you bump one. They're mounted on posts that weigh 4 pounds per foot, pounded into the ground by a bald guy covered in tattoos. You don't want to gently caress with that guy. So no, it's not really possible to cut the cost. Signs aren't just pieces of plastic with some sharpie scribbles. They're serious hardware.
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Feb 5, 2010 04:45
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A few updates: 1) With the help of another goon, I've put up a couple articles on traffic engineering. They're similar to what you've read here, but if you want to share with those who don't have an account, well, here you go. Highway Handbook: A Field Guide to Interchanges Highway Handbook: Why We Speed 2) For those of you wondering when Connecticut's going to change all its exit signs to be mile-based, there's a good chance we will not be adopting the new MUTCD. Some of the changes (red arrows on signal heads, countdown ped signals, brighter signs) are already taking place, but we won't be doing everything The Book says. 3) And a quiz! Each of Connecticut's 169 towns has a number, going in alphabetical order. 1 is Andover, 2 is Ansonia, 3 is Ashford, and 169 is Woodstock. However, right after Salisbury (121) is 122, Deep River. If the towns were in order, Deep River would be in the 30s. So, why is it out of place? Answer: Deep River was, until about 80 years ago, known as Saybrook. They changed the name but, rather than shift 80+ town numbers up by one, Deep River has kept its old number.
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Feb 7, 2010 04:29
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With the entire mid-atlantic buried under feet of snow now, I'm curious: Are there any special precautions you have to take when accounting for traffic in snowy conditions? What about designing for stuff like plows or salting.
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Feb 7, 2010 07:31
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Cichlidae posted:
Signs also generally last a really long time if they're made well. A lot of Connecticut's signage that's being replaced these days is over 20 years old. Hell, there's still some 1970s (and 60s!) era signage in Massachusetts, though the stuff that is there is exceedingly rare. It's not really freeway signs, though - there's "paddle signs" (small green signs used on intersections) and route assurance markers of various ages that just doesn't get replaced. kefkafloyd fucked around with this message at 08:04 on Feb 7, 2010 |
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Feb 7, 2010 08:01
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Assuming that you allow right-turn-on-red, generally how long do you let a car in a right-turn-only lane to wander/waffle/wait until triggering a green for that road? Hope that makes sense.
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Feb 7, 2010 08:50
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Frinkahedron posted:With the entire mid-atlantic buried under feet of snow now, I'm curious: Are there any special precautions you have to take when accounting for traffic in snowy conditions? What about designing for stuff like plows or salting. Lots and lots! Our pavement markings are meant to be run over by plows (hence why we don't have raised pavement markers in Connecticut). Concrete slabs like bridge decks have to be designed for the heavy salt applied and also to have plenty of air bubbles (still only a few percent) inside to account for the expansion of water when it freezes. Catch basins have to deal with all the sand and salt that gets dumped on the road. We design, where space permits, a 5- to 10-foot-wide strip of grass between the road surface and sidewalk called the "snow shelf" to store snow when plowed. We have little poles on top of fire hydrants so plows won't hit them when they're covered in snow. Some people even lean huge sheets of plywood against their mailboxes for the same reason. kefkafloyd posted:Signs also generally last a really long time if they're made well. A lot of Connecticut's signage that's being replaced these days is over 20 years old. Yep, we can't even afford to replace the overhead signs more often than once in 20 years. And, when we finally do replace them, they're still in passable condition more often than not. The very oldest signs are still around not because they're in good shape, but rather because we don't have a sign inventory. Isn't that awful? Hundreds of thousands of signs out there, and some are bound to be forgotten and never replaced. Mandalay posted:Assuming that you allow right-turn-on-red, generally how long do you let a car in a right-turn-only lane to wander/waffle/wait until triggering a green for that road? That's an easy one! Eight seconds. Of course, that assumes the driver doesn't pull up past the loop detectors and miss them entirely. We set the delay on right-turn detectors to eight seconds here, though I've seen four or five on some older signal plans.
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Feb 7, 2010 17:26
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I've seen you mention the Chicago intersection of I-290 and I-90/94, but I have a specific question, based on how I used to drive on it a lot. I-290 runs east/west, with 90/94 going north/south. A short distance past the interchange, 290 turns into a city street, so if you want to go into downtown, you go straight, while people that need to go north/south exit. However, there's a huge problem with this. The north & south exit lanes are both a single lane apiece. Invariably, this traffic backs up through the ramps, and 290 starts to back up. Being the canny Chicago driver everyone considers themselves to be, people pass the exit lanes and then try to merge over. However, as the lanes aren't moving at all, there's no place to merge, and traffic halts in the other 3 lanes. This eventually stalls out the entire interstate, which is really frustrating when you're trying to get into the CBD. How could this be prevented? The only thing I can think of is a lot more signage, and installing Jersey barriers that extend at least a half mile back from the ramps. This would keep people from trying to dodge in at the last second, but what likely would happen is force the start of the barrier to be the new chokepoint.  Click here for the full 837x465 image. mastershakeman fucked around with this message at 01:19 on Feb 9, 2010 |
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Feb 9, 2010 01:14
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mastershakeman posted:I've seen you mention the Chicago intersection of I-290 and I-90/94, but I have a specific question, based on how I used to drive on it a lot. We have the exact same problem on I-84EB in Hartford approaching I-91. The right two lanes are exit only. Like you said, putting in a barrier would only move the chokepoint further upstream. Our solution was to extend the solid white line a half mile back on I-84. It's legal to cross a solid white line (at least in CT), but it still deters some of the last-minute merging. I don't think there's a practical way to stop it entirely. Edit: I just remembered, there's a way to statutorily prevent this sort of situation, and that's installing "No Passing" signs in the problem area. It requires heavy enforcement and would apply to all lanes, not just the exit lanes, which is rather inconvenient. I don't know if you'd consider that entirely practical. Cichlidae fucked around with this message at 13:11 on Feb 9, 2010 |
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Feb 9, 2010 04:02
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http://www.statesman.com/news/local/u-s-290-fix-more-vexing-than-expected-198172.html I'm curious, how common can something like this be? The article says that things like this is rare for embankments under 20 years old, but that's only half the answer IMO. tl:dr version of the article: People find pea gravel in drainage trap, investigate, find that almost 200 cubic yards had escaped. Proposed fix is to drill holes and fill them with concrete to fill the voids. During the drilling, the section of highway sunk 20 inches and they had to double the repair budget to fix it.
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Feb 9, 2010 14:52
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grnberet2b posted:http://www.statesman.com/news/local/u-s-290-fix-more-vexing-than-expected-198172.html It sounds like the contractor cut corners and either didn't backfill the pipe correctly or used substandard materials. This sort of thing happens on pretty much every project, to an extent. Back in 2006, I think, the roof panels of one of the Big Dig tunnels in Boston collapsed and killed someone because a contractor cut costs on the bolts that held the panels in place. The effects aren't usually so severe, though; things like applying a thinner than specified coat of paint or re-using worn out drums and signs that really shouldn't be used are commonplace. Often, the effects won't be noticed for decades, or not at all.
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Feb 9, 2010 18:42
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Figured I'd post my favorite intersection, from the town I grew up near: Click here for the full 1022x466 image. The picture is facing to the east, with the major road going through town running east/west. The picture shows the other major road into town that runs north/south, it dead ends just to the north of the intersection, so it's essentially a T intersection with a little dead end above the T. See the stop sign I circled? That's the only stop sign. Going east. So if two cars, one driving north, and one driving west, both make left hand turns, neither has a stop sign and their paths intersect. Oh, and the sidewalk on the SE corner was installed by myself because otherwise kids would walk in the street.
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Feb 10, 2010 01:57
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