|
kefkafloyd posted:Aside from the previously mentioned Putnam bridge, there aren't really alternatives to cross the river northbound. There is no direct I-91NB >I-84 EB interchange in the city, so the Bulkeley Bridge is not an alternative. Granted, it's not like southbound traffic has it much better. If you're going to anywhere between Bridgeport and New London, you've got no alternatives. Dominus Vobiscum posted:That's what I get for doing ballpark math in my head instead of putting it all in a spreadsheet like real traffic engineers do. Nice to know I came up with something reasonable, at least. Here's a quick rendition of what I came up with, for reference. 6 structures, full lane continuity, matches existing lane use as well. The next step is checking out that third dimension and seeing whether we can actually fit all this stuff at the end of a runway. 
|
#
?
Jan 5, 2012 23:42
|
|
|
|
| # ? Apr 29, 2024 14:18 |
|
|
Ah the time factor would explain a lot, you could always choose to go cheapskate and introduce shoulder running or something though, mess it up european style. On the reusing thing: around here they'd rather reuse as much as possible if it's up to both constructional and dimensional standards and be creative with temporary roads during traffic works. So if this were a factor, together with high structural costs for any vertical weaving and a gut feeling that most of the bare land around the interchange is already state owned, you could always mess around with local connectors in the southern portion of the area: 
|
|
#
?
Jan 6, 2012 00:37
|
|
|
A very crude drawing. Southbound would be a merge/split, but northbound wouldn't be because the traffic is too high for the length of road. SB has off-ramps on both the left and right for each highway, so no major weaving to off-ramps is necessary. I-91 NB has 4 lanes; CT 15/US 5 NB has 3; SB merge has 7 (4 from I-91, 3 from CT 15/US 5) I-91 NB to CT 15/US 5 SB would have to use Brainard/Airport road. Each freeway to freeway ramp has 2 lanes. Airport road SB on-ramp has 2 lanes. Some ramps I think could be done better (CT 15/US 5 NB to I-91 NB, Brainard to I-91 NB) and I am worried about the weaving necessary in the merge/split.
|
|
#
?
Jan 6, 2012 00:55
|
|
|
Koesj posted:Ah the time factor would explain a lot, you could always choose to go cheapskate and introduce shoulder running or something though, mess it up european style. On the reusing thing: around here they'd rather reuse as much as possible if it's up to both constructional and dimensional standards and be creative with temporary roads during traffic works. Just curious, how would you manage this, vertically?  Silver95280 posted:A very crude drawing. Interesting idea, but that's a lot of left entrances and exits. You could take out a couple of those ramps, like this one, since the movement can already be covered. The weaving isn't so bad, since the whole interchange is a mile long. 
|
|
#
?
Jan 6, 2012 01:27
|
|
|
Cichlidae posted:Just curious, how would you manage this, vertically? Not. Just a traffic light, bit of an imaging lay-out problem I guess. I've cut that connection in my latest iteration anyway since it's a bit of a kludge. I think you could even manage to keep traffic going during construction:   
Koesj fucked around with this message at 01:50 on Jan 6, 2012 |
|
#
?
Jan 6, 2012 01:45
|
|
|
Koesj posted:Not. Just a traffic light, but of an imaging lay-out problem I guess. I've that connection in my latest iteration anyway since it's a bit of a kludge. That's a really cool idea. I'll show it to my boss tomorrow, if you don't mind.
|
|
#
?
Jan 6, 2012 01:48
|
|
|
Cichlidae posted:That's a really cool idea. I'll show it to my boss tomorrow, if you don't mind. No prob.
|
|
#
?
Jan 6, 2012 01:49
|
|
|
Cichlidae posted:Now that there are retroreflectivity standards for striping in the works, you wouldn't even have to go that far. A couple of years ago I worked in the retroreflectives business for a certain company headquartered in the US Midwest who have a pretty big business in all things retroreflective. I am in Australia, so different market and all, but down here there was a lot of effort over many years from a bunch of suppliers (not just us) to get enforceable retroreflectivity standards for stripes but the biggest obstacle was the substantial maintenance cost this would mean for the local DOT...how is that going to be managed over there? I am now in a totally different field (mining industry!) but I loved my time working in that business. Efresh fucked around with this message at 11:40 on Jan 6, 2012 |
|
#
?
Jan 6, 2012 11:28
|
|
|
Efresh posted:A couple of years ago I worked in the retroreflectives business for a certain company headquartered in the US Midwest who have a pretty big business in all things retroreflective. I am in Australia, so different market and all, but down here there was a lot of effort over many years from a bunch of suppliers (not just us) to get enforceable retroreflectivity standards for stripes but the biggest obstacle was the substantial maintenance cost this would mean for the local DOT...how is that going to be managed over there? 3M is single-handedly responsible for our standards. They sponsored studies on retroreflectivity, and then petitioned the NCUTCD to recommend their findings as a standard. Legally speaking, it's not a law to have visible pavement markings, so the legislature doesn't get involved one bit. 3M did the same thing for sign face sheeting, which made it into the 2009 MUTCD amid quite the furor. The media picked up pretty quickly that many of the required changes had little or no safety benefit, and were brought about due to lobbying. As to the cost, the NCUTCD doesn't really consider that. Nobody can manufacture pavement markings that last 10 years at the required retroreflectivity levels. We're supposed to replace them every year or two now... after having a 60-year-old engineer drive around at night and choose the places that seem to be fading.
|
|
#
?
Jan 6, 2012 13:30
|
|
|
My superficial feelings are that Massachusetts' striping seems far worse than Connecticut's. Route 128, 95 around Danvers, all of 93 north of 128, parts of the turnpike have stripes that are barely visible even on the nicest of nights. It feels like the only time Massachusetts redoes the striping is when the road gets repaved, which is not a sufficient enough schedule to keep the striping visible. When it rains on 128 at night, it's pretty drat dangerous. Fortunately, the stretch I drive most often (Waltham to Burlington) has been recently repaved, so there's nice, fresh new stripes.
|
|
#
?
Jan 6, 2012 15:33
|
|
|
There is a CVS near me that has a stop sign at the exit, and they clearly went for the cheap version instead of the proper one. During the day it looks fine, but at night, the red isn't reflective at all. All you see is STOP. I'm surprised it's legal to sell stop signs that aren't quite right, to be honest.
|
|
#
?
Jan 6, 2012 17:16
|
|
|
I drove through a stop sign that was put up in an intersection that had never had a stop sign before, and frankly didn't need one. After I realized I'd blown the new sign, I pulled over and went back to check. I probably didn't notice it because the sign was the wrong size, the wrong height on the electrical pole, the attachment hardware was poorly installed and not correct for the sign, and it was crooked. I called 911 to report a suspected fraudulent stop sign, and it was gone by that evening. The beat cop said that the city had "accidentally" installed the signs orthagonal to the correct intersection, that is, they put them on the N-S when they were supposed to be E-W, but I think he was bullshitting me and the signs were put up by residents who thought it was needed.
|
|
#
?
Jan 6, 2012 18:09
|
|
|
smackfu posted:There is a CVS near me that has a stop sign at the exit, and they clearly went for the cheap version instead of the proper one. During the day it looks fine, but at night, the red isn't reflective at all. All you see is STOP. I've seen shopping centers with green stop signs, painted wood. As a matter of course (and when it's safe to do so), I drive right through substandard stop signs. I don't want to risk being rear-ended over someone's beautification project. As to what's legal and illegal, we frequently bend the law for businesses. In CT, it's illegal to have any commercial sign with "stop" or "slow" on it within sight of the road, or anything that appears to mimic a traffic control device. Stop & Shop's very name means it shouldn't be allowed any signs, doubly so since its old logo is a traffic signal head.
|
|
#
?
Jan 6, 2012 23:56
|
|
|
Cichlidae posted:I've seen shopping centers with green stop signs, painted wood. As a matter of course (and when it's safe to do so), I drive right through substandard stop signs. I don't want to risk being rear-ended over someone's beautification project. One of the things I like about the 2009 MUTCD is that FHWA put in new language making it applicable to private roads, however much that will actually get enforced.
|
|
#
?
Jan 7, 2012 00:08
|
|
|
Opinions on Rt. 495 stretching through the Lawrence areas?
|
|
#
?
Jan 7, 2012 02:39
|
|
|
Cichlidae posted:As to the cost, the NCUTCD doesn't really consider that. Nobody can manufacture pavement markings that last 10 years at the required retroreflectivity levels. We're supposed to replace them every year or two now... after having a 60-year-old engineer drive around at night and choose the places that seem to be fading. Yeah that's the thing with stripes. Modern signage will meet the minimum reflectivity standards for as along as the sign is still standing (20 years plus), but paint or thermoplastic on busy roads will be done in as little as a few months in some cases. Do you think that creates a serious liability for the local DOT? It isn't much of a stretch to think of situations where someone would try suing over bad striping.
|
|
#
?
Jan 7, 2012 03:07
|
|
|
FFStudios posted:Opinions on Rt. 495 stretching through the Lawrence areas? Don't know anything about it, honestly. I'll look over it in the coming week  Efresh posted:Do you think that creates a serious liability for the local DOT? It isn't much of a stretch to think of situations where someone would try suing over bad striping. Absolutely, which is why there's a lot of opposition to putting it in the MUTCD. We'd need to spend hundreds of millions of dollars a year to keep our striping up to spec, though, so a few million a year in lawsuits seems like small change in comparison...
|
|
#
?
Jan 7, 2012 03:25
|
|
|
Main interesting parts about I-495 are the double-decker bridge over the Merrimack and the brand new on-ramps they built for it.
|
|
#
?
Jan 8, 2012 20:57
|
|
|
Your project looks like a big version of the 696, M-10, Telegraph interchange in Michigan: http://g.co/maps/9pgd4 Zero One fucked around with this message at 04:37 on Jan 9, 2012 |
|
#
?
Jan 9, 2012 04:27
|
|
|
I dunno if this has been asked (because I've been reading this thread for 2.5 years now) before, but how important is symmetry in designing your traffic solutions? I mean, basically to the point where it's possible, are there measurable benefits to a piece of construction that is radially or laterally symmetrical? I just notice a lot of things (like this picture above my post) that end up being symmetrical in a really beautiful way. When it comes to load bearing I know symmetry (or I guess chirality?) is helpful, does traffic optimization work out in the same way?
|
|
#
?
Jan 9, 2012 04:32
|
|
|
Zero One posted:Your project looks like a big version of the 696, M-10, Telegraph interchange in Michigan: Unfortunately, we don't have nearly as much room to work with laterally: 1500 ft vs. 500. Stew Man Chew posted:I dunno if this has been asked (because I've been reading this thread for 2.5 years now) before, but how important is symmetry in designing your traffic solutions? I mean, basically to the point where it's possible, are there measurable benefits to a piece of construction that is radially or laterally symmetrical? There are some notable benefits: - Driver expectancy. No matter which way they drive through, the order of exits and entrances, as well as the relative spacing, is the same. That means fewer last-minute mistakes and accidents. - Parity of access. If a ramp is provided for one movement, its conjugate ramp will be provided in the opposite. This makes planning trips much easier, as you can use the same route you took on the way there to get back. - Even peaks. About the same number of people will take the route on the way to work as they will on the way home. Makes planning simpler. - Constructability. Building 4 of the same structure is easier and cheaper than building completely different ones. They're interchangeable, which makes maintenance easier, and design time is much faster.
|
|
#
?
Jan 9, 2012 13:31
|
|
|
FFStudios posted:Main interesting parts about I-495 are the double-decker bridge over the Merrimack and the brand new on-ramps they built for it. Having looked at it in detail, that's one great set of interchanges. There is full access to/from all directions, no weaving on the main line, all right exits/entrances, and reasonably compact. A few of the routes are circuitous, but it's better than the alternative of having to pull a U-turn somewhere. If there's one downside, it's that the non-freeway roads seem to have suffered somewhat in the transition. There's not too much I could have done better to avoid that.
|
|
#
?
Jan 9, 2012 23:23
|
|
|
Cichlidae posted:There are some notable benefits: We're fast moving away from these things in the Netherlands though, nice symmetrical interchanges built during the 60ies and 70ies are being majorly rejigged. Case in point: the A9 realignment and reconstruction of the Badhoevedorp interchange from this to this (large PDF).
|
|
#
?
Jan 10, 2012 19:48
|
|
|
Koesj posted:We're fast moving away from these things in the Netherlands though, nice symmetrical interchanges built during the 60ies and 70ies are being majorly rejigged. Economy and right-of-way acquisition usually trump those things, unfortunately. If I could flatten the map and just build wherever I wanted, there'd be a ton of symmetry, but the biggest concerns tend to be fiscal.
|
|
#
?
Jan 11, 2012 02:53
|
|
|
Koesj posted:1) Why does NB I-91 need to cross NB CT-15 twice? Is it a question of re-using the same roadway? Seems like you could save some roadway length by having the ah gently caress it Here's a lovely rendition. I've eliminated some bridges, retained the railway ROW, and lengthened the merging area for the ~1000 local road cars going NB I-91. 
|
|
#
?
Jan 11, 2012 03:31
|
|
|
Mandalay posted:1) Why does NB I-91 need to cross NB CT-15 twice? Is it a question of re-using the same roadway? Seems like you could save some roadway length by having the The one issue I see there is that you've lost lane continuity on I-91 NB, since it has a left exit to 15 NB. Not a huge issue, though. I'll get the latest version of VISSIM on my computer tomorrow, and give these a spin. I want to make the best design possible.
|
|
#
?
Jan 11, 2012 04:37
|
|
|
I think you should creatively use loops and rolls to make more effective use of the third dimension for crowded interchanges. You could completely replace cloverleafs with corkscrews, and in a fraction of the space! Slow driving strictly prohibited 
grover fucked around with this message at 04:55 on Jan 11, 2012 |
|
#
?
Jan 11, 2012 04:50
|
|
|
I also learned everything I need to know about road design from Stunts.
|
|
#
?
Jan 11, 2012 06:10
|
|
|
Mandalay posted:1) Why does NB I-91 need to cross NB CT-15 twice? Is it a question of re-using the same roadway? It's all about traffic flow-optimisation. From a structural engineering point of view the CT-15 bridge is something you probably can't and don't want to touch which imposes a lot of ROW constraints since the bridge doesn't land right in the middle of the corridor but off towards its western side. This can't really be tweaked since the horizontal alignment of the bridge approach needs to conform to minimal curvature standards. It also means that it's going to be much easier to find room to avoid unnecessary weaving and split up northbound traffic early than vice-versa. Now there's both a much higher hourly peak in northbound traffic and the current interchange has a lay-out where CT-15N has to first cross the corridor median before splitting towards both northbound directions and I-91N has to do the same to dump the majority of its northbound traffic. The neat thing here is that the split between mainline I-91 northbound traffic (4.7k) and the smaller amount of turning traffic towards CT-15N (2.4k) can take place while using existing bridges, preserving mainline continuity on I-91N and providing for an even split of CT-15 northbound traffic (2.1/2.0k) pretty much within existing road right of way! I tried my best to keep northbound merging traffic from Airport Road as far away from the CT-15N split as possible but I'd rather have used the existing I-91 offramp towards the CT-15 bridge for a dedicated local connector. Still, rail ROW pretty much precludes this solution so I deleted it in the second iteration of my design. These problems don't really apply to the southbound direction: Both the merge and split occur at a shallow angle (rather than the oblique underpass crossings turning traffic from the northbound CT-15 and I-91 have to make), there's a relatively long distance on which weaving can take place and only around 40% (3600vph) of this traffic needs to change lanes to get where they want to go anyway. It really seems that the westward landing of the CT-15 bridge makes a cheap symmetrical parallel setup a pain in the rear end by the way. I'm glad the biggest priority in this redesign, getting the highest peak direction in traffic to flow unobstructed, has got both the room to split and existing bridges to make the most use of. Koesj fucked around with this message at 07:14 on Jan 11, 2012 |
|
#
?
Jan 11, 2012 07:09
|
|
|
Cichlidae posted:The one issue I see there is that you've lost lane continuity on I-91 NB, since it has a left exit to 15 NB. Not a huge issue, though. I don't see how lane continuity is an issue because nothing is feeding into I-91NB until right before the bridge. I would argue that the "left exit" to CT-15NB is more of a "split of freeways" not unlike the I-805SB/I-5SB split in San Diego. Koesj posted:From a structural engineering point of view the CT-15 bridge is something you probably can't and don't want to touch which imposes a lot of ROW constraints since the bridge doesn't land right in the middle of the corridor but off towards its western side. This can't really be tweaked since the horizontal alignment of the bridge approach needs to conform to minimal curvature standards. Cichlidae posted:Going with all-new structures here could have a very big advantage. They could be built off-line, with traffic still flowing on the old alignment. Maintaining traffic during construction is going to be a nightmare, I don't even want to think about it yet... Just because CT-15 currently lands in the middle of I-91 doesn't mean it's a Good Idea, right? I understand that you're trying to re-use roads, but isn't this an opportunity to break free of old designs? Also it would be rad if we could fit a fourth lane going I-91N but this is probably firmly in the "Nice to Have" category.
|
|
#
?
Jan 11, 2012 18:51
|
|
|
quote:I don't see how lane continuity is an issue because nothing is feeding into I-91NB until right before the bridge. I would argue that the "left exit" to CT-15NB is more of a "split of freeways" not unlike the I-805SB/I-5SB split in San Diego. There's 50% more I-91NB traffic than turning traffic towards CT-15NB though. Mandalay posted:I understood about half of your post because my bachelor's was in Industrial and not Civil Engineering... I'm not a native speaker so that might be the problem right there. Then again, I'm a historian and not an engineer so the essentials can be easily grasped even by my own addled arts & humanities mindset. quote:...but my inspiration to mess with the alignment here came from this quote: (...) Just because CT-15 currently lands in the middle of I-91 doesn't mean it's a Good Idea, right? I understand that you're trying to re-use roads, but isn't this an opportunity to break free of old designs? According to the traffic numbers it's not functioning that badly right now. With future growth the distribution traffic density on the splits and merges is going to be a problem though. The problem here is going to be I-91NB traffic needing two lanes approaching CT-15NB, which would mean building a new bridge towards the CT-15 main span. In my ballpark estimate from halfway across the world this can be solved by using existing bridges and not having to add any major structural costs to the project. quote:Also it would be rad if we could fit a fourth lane going I-91N but this is probably firmly in the "Nice to Have" category. That's not really necessary if peak hourly density is going to be 4700 vehicles per hour, 3 lanes can easily carry that amount. With all the problems financing public works in the US I'd rather keep the option open to introduce shoulder running later on. A certified eurotrash cost-cutting solution.
|
|
#
?
Jan 11, 2012 20:14
|
|
|
Koesj posted:There's 50% more I-91NB traffic than turning traffic towards CT-15NB though. Your English is perfect--the problem is my lack of Civil Engineering experience. Does it really matter that I-91NB is splitting left and CT-15NB is splitting right? There are zero merges in that diagram south of the split, which means that signs can be posted to indicate lane assignments easily. It seems to work in real life (I posted that San Diego I-805SB/I-5SB split). And you save literally millions of dollars in bridging costs. My (possibly very mistaken) assumption is that Cichildae has the opportunity to design a system that will last beyond the operational life of the existing bridges.
|
|
#
?
Jan 11, 2012 21:36
|
|
|
Maybe I'm misremembering but wasn't one of the problems also that the existing bridges were getting old so would need to be replaced anyway?
|
|
#
?
Jan 11, 2012 21:55
|
|
|
Mandalay posted:Does it really matter that I-91NB is splitting left and CT-15NB is splitting right? There are zero merges in that diagram south of the split, which means that signs can be posted to indicate lane assignments easily. It seems to work in real life (I posted that San Diego I-805SB/I-5SB split). True, I've looked at it a bit more and from a practical perspective it shouldn't make that much of a difference. quote:And you save literally millions of dollars in bridging costs. This however I don't understand since traffic coming from I-91 towards CT-15NB currently has to use an onramp which would need to be (expensively) widened to two lanes if you want to avoid having unsafe lanes of less than 10 feet without any hard shoulder or decent safety margin on that particular ramp. I'm only reusing bridges in the northern part of the interchange and realigning surface level connectors, that should be cheaper overall comparing to even your admittedly straightforward and streamlined design. quote:My (possibly very mistaken) assumption is that Cichildae has the opportunity to design a system that will last beyond the operational life of the existing bridges. Roflex posted:Maybe I'm misremembering but wasn't one of the problems also that the existing bridges were getting old so would need to be replaced anyway? This is might all very well be true. I'd realign the whole corridor to better connect with local roads if bridge replacement was one of the main goals. However, Cichlidae's main argument for possible bridge replacement was convenience during interchange reconstruction. Here in Holland they'd rather recapitalize existing structures if adequate throughput during construction can be guaranteed, something I've tried to address in the second picture of my three pronged design (I did miss a connection there but it can be remedied). edit: Now: http://g.co/maps/hvr9x Plan:  edit2: Ouch, the excess width of the northbound bride approach is just as narrow as the onramp  Koesj fucked around with this message at 01:00 on Jan 12, 2012 |
|
#
?
Jan 12, 2012 00:24
|
|
|
You guys are putting a lot more thought into this than I'd guessed, and that's awesome! I'm going to spend tomorrow looking at a few different iterations of our designs in VISSIM. That should help sort out the third dimension, as well as find out how severe any weaving problems are. The more options that we can put together, the better, because there are always unforseen problems. I've already found a pretty big problem with my design: putting all of that traffic through two signals causes them to hit LOS F in both peak hours. Because of a directive from my bosses, we're not allowed to build 2-lane on-ramps onto freeways. Even without that, though, the bottleneck is at the signal itself; pumping 1400 cars into a double left is just more than we can handle. How do we fix it? I'm going to break up the ramps so that each intersection only has to handle a few different maneuvers.
|
|
#
?
Jan 12, 2012 00:59
|
|
|
Yeah you'll need more direct connectors...
|
|
#
?
Jan 12, 2012 01:02
|
|
|
Cichlidae posted:I've already found a pretty big problem with my design: putting all of that traffic through two signals causes them to hit LOS F in both peak hours. Because of a directive from my bosses, we're not allowed to build 2-lane on-ramps onto freeways. Even without that, though, the bottleneck is at the signal itself; pumping 1400 cars into a double left is just more than we can handle. What's wrong with Koesj's design?  If you break up the ramps, you're going to have weaving issues...
|
|
#
?
Jan 12, 2012 01:08
|
|
|
Mandalay posted:What's wrong with Koesj's design? Nothing from what I've seen so far. Again, there doesn't need to be something wrong to merit alternatives. It's always a good plan to have multiple options.
|
|
#
?
Jan 12, 2012 01:29
|
|
|
I got a wonderful email today! WE HAVE BEEN ASKED IF WE WOULD LIKE TO UPDATE OUR TRAFFIC LOGO SO I AM LOOKING FOR SOME SUGGESTIONS FROM OUR USERS. THE NEW ONE SHOULD BE SIMILAR IN SIZE. CURRENT LOGO SHOWN BELOW.  If you have any ideas, I'd be glad to forward them. The logo should be in black and white, as it gets printed on every single plan we do. Anyway, I spent all morning working on VISSIM. I did up the current configuration to see how it does in current loading, and in the future. It didn't turn out as badly as I'd expected, so obviously I need to dumb down the drivers to make it more realistic.  Morning peak.  Evening peak.  Evening peak with 25% growth. I drove through it twice today, and even at 2 pm, traffic is very rough.
|
|
#
?
Jan 12, 2012 21:07
|
|
|
|
| # ? Apr 29, 2024 14:18 |
|
|
drat that looks so cool.
|
|
#
?
Jan 12, 2012 23:03
|
|