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A question about merging. Click here for the full 939x609 image. That's where I-95 merges with I-476 (The Blue Route, a segment of highway that took almost 30 years to complete construction of and which is probably taught as a cautionary example in traffic engineering textbooks) outside of Philly. Ignore the two westbound lanes at the top of the screen grab, they're exit lanes. Look at the 4-lane merge below those. See how the left of the top two lanes has merge arrows painted on it? Those two lanes are the big swooping offramp from I-95N, and there are signs telling people in that lane to merge right, because the lane's ending, and merge arrows painted on the lane for hundreds of yards. But the lane doesn't actually end on the offramp, it ends at the merge, where the two lanes from I-95N mix with the two lanes from I-95S, merging first down into three and then into two lanes. Obviously and as you'd expect, this *sucks*. Nobody ever merges on the offramp, everybody waits until the last second, so this area gridlocks constantly under traffic loads that just don't justify it. Given that a) American drivers suck at merging, b) everyone knows they suck at merging, and c) traffic at a merge can be brought to a halt by a single chunderfuck doing it wrong, wouldn't it be better to actually merge the offramp traffic *on* the offramps, and force people to actually obey the "get right, dumbass, this lane is ending" control? Then you'd be bringing two lanes together into two lanes of traffic, instead of having everyone trying to merge in all directions within about 1000' of each other. For that matter, I often wonder whether it wouldn't be better for a merge area to terminate with a brick loving wall with spikes sticking out of it in the lane that's ending, rather than the hundreds of feet of widened lane that lane-jumpers roar down and try to edge out merging traffic on.
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Aug 20, 2010 15:43
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Phanatic posted:Obviously and as you'd expect, this *sucks*. Nobody ever merges on the offramp, everybody waits until the last second, so this area gridlocks constantly under traffic loads that just don't justify it. Traffic is going to back up when the road approaches the limit of capacity regardless how how people treat this merge. You need to look at this not as cheaters or assholes, but as a question of game theory. Only losers merge early; if everyone would merge at the same time instead of half the people merging WAY too early, both lanes would be the same length and everyone would have a completely fair wait. In other words, you and roughly a third of the other schmucks in the right lane should be driving in the left lane instead of angrily shouting and road raging. If you can't beat 'em, join 'em! grover fucked around with this message at 15:53 on Aug 20, 2010 |
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Aug 20, 2010 15:50
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grover posted:
What you should do is avoid the areas where everyone's stopped trying to force their way in. The two lanes on the right are merging into each other, *and* merging into the right lane of the pair on the left at the same time. gently caress that, you don't want to be there, you get in the left lane and avoid that mess. Then then the two lanes of the left pair merge together, which is another mini-parking lot, so now you get into the right lane and avoid *that* mess. At worst, it takes three minutes to get through. If you actually try to merge into any of the areas where people are merging, you're hosed. I've never seen problems caused by "merging too early." It's the dipshit who, in a condition of completely open traffic low, goes down the travel lanes only to jump over onto the exit ramp at the last possible second who tends to gently caress things up for everyone.
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Aug 20, 2010 16:09
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Regarding merging: Phanatic, we have a similar situation in New Haven where I-91 runs into I-95. The two lanes of 91 merge on the ramp itself, but we're changing that so that they merge slightly after joining 95 (a common situation in multi-lane merges). Some places have four lanes merge into three: the right lane on the left roadway and the left lane on the right roadway become one. No taper, no warning arrows, just squishing two lanes of different-speed traffic into one. Merges are most efficient when everyone merges in the same place, and well ahead of the bottleneck. Like grover says, though, the driver who cheats ends up benefiting at everyone else's expense. A big spike-covered barrier wouldn't help. I've seen people drive right up alongside a jersey barrier to merge literally in the last 5 feet. One (expensive) way that engineers have found to promote effective merging is to put up a series of electronic signs ahead of the work area that can be lit to say "DO NOT PASS." Each one is lit in succession as the queue reaches it, and if cars don't merge (or choose their position in line) by that point, the cop parked behind the sign gives out tickets.
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Aug 20, 2010 20:02
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 Should have voted for that bond issue, fuckers! (Yes, it's a 'shop)
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Aug 21, 2010 02:57
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Shavnir posted:Man its Muncie. I used to walk across this every day What up, walked-across-this-intersection-every-day crew. Personally, the thing that drives me craziest about Muncie's traffic is this beauty. For the people lucky enough not to live here: the middle road there, McGalliard, is the main commercial drag in town. The bottom road to the left is the frontage road for Wal-Mart and to the right goes straight to the university. The top road just has a ton of commercial stuff on it as well. The bottom of those three intersections is just a stop sign with 2 lanes entering from all three major directions. There's never enough time for all the traffic that gets backed up on Chadam waiting to cross McGalliard and then immediately turn left onto Clara/Bethel, so of course half the time people moronically pull out right into the middle of the intersection and end up sitting there as McGalliard has the green for minutes at a time until the idiots at the stop sign can remember how to drive. (As an added bit of stupid, turn on the labels and notice that the road coming from the southeast is Bethel... and becomes Clara, while Fox Ridge running from the northeast becomes Bethel as it goes west. Makes sense when viewed from a zoomed-out map, but the first time you drive up to it... Last week was move-in week for the university. Every drat person new to this town trying to get to the university comes through this intersection on McGalliard from the west. I stay far, far away that week.) I suppose that intersection on the bypass that kills someone every drat year is probably a bigger social concern than this intersection, but drat it, this one makes me wait two minutes when I shouldn't have to 
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Aug 23, 2010 05:49
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Flavor Text posted:What up, walked-across-this-intersection-every-day crew. Personally, the thing that drives me craziest about Muncie's traffic is this beauty. Amazing that it's not signalized; usually a Wal*Mart by itself is enough to warrant a signal, let alone on a multi-lane road at an intersection within 200 feet of another signal. A signal there with coordination could work beautifully.
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Aug 23, 2010 12:44
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Here's an article about the new hybrid pedestrian lights in Phoenix. Regular readers will remember a video posted earlier of cars creeping through them in confusion. http://www.azcentral.com/news/articles/2010/08/19/20100819hawk-lights-lower-phoenix-pedestrian-deaths.html The article says they're safer, at least for now, but I'm not sure if that'll bear out. People are often dazzled by new things, but eventually get used to them and stop paying attention.
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Aug 23, 2010 21:43
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Cichlidae posted:Here's an article about the new hybrid pedestrian lights in Phoenix. Regular readers will remember a video posted earlier of cars creeping through them in confusion. Another reason to avoid Arizona. Just how the hell is this different than putting in a normal red/green signal that people are actually familiar with? The entire article goes on and on about how much safer these lights have made the crossings, but if you read carefully you'll notice that's in comparison to crossings that don't have red lights. Well, no poo poo people will stop at a red light! I wonder if any of the studies mentioned compared the HAWK signal heads to standard signal heads. My town has a few different ways of doing pedestrian crossings: 1) Pressing a crosswalk button can activate flashing yellow lights embedded in the roadway along the crosswalk. This is better than nothing at all but can still be hard to see when traffic is in front of you and isn't particularly apparent during bright daylight either. Earlier in this thread you (Cichlidae) mentioned those are much cheaper than building full-blown signal heads, so I guess they have that going for them. 2) Pressing a crosswalk button can activate a large blinking yellow signal head at either end of the crosswalk. That's less likely to be obscured by other traffic, but by the time you've gone that far why not spend a little extra money and put a real signal head on there? 3) Pressing the crosswalk button can turn a normal signal head from green to red, stopping traffic for the pedestrians. The signal is always green except when a pedestrian wants to cross so it doesn't confuse drivers, and it'll cycle through yellow to red immediately when they hit the button so there's no reason for impatient pedestrians to jaywalk. They're awesome. Obviously this is more expensive because you have to build the whole signal head structure, but where there are dangerous crossings (ie. in front of a school) it's worth it. I don't see how these HAWK lights are any different than #3, except that they look different and they have a blinking red (stop sign) phase, which is perfectly doable (and familiar) with a standard signal head (we don't do that here, but I've seen it done in other parts of So Cal). The article claims they only cost half as much to install as a normal signal, but based on the photo the infrastructure is identical, so that makes no sense to me whatsoever (perhaps they're able to avoid certain bureaucratic red tape because these aren't classified as normal traffic signals?). It's like they're different for the sole purpose of being different, because there's no actual functional reason behind it. How can that be a good thing?
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Aug 23, 2010 23:04
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Or you could do what my town did and throw a pair of stop signs in the middle of the block, and assign two cruisers to sit on either side of the crosswalk ready to stop and ticket anyone who doesn't stop, roll back, and wait three seconds on the off chance that one of the two pedestrians who use that crosswalk (instead of the one at the end of the block) decide to cross.
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Aug 24, 2010 00:19
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Choadmaster posted:It's like they're different for the sole purpose of being different, because there's no actual functional reason behind it. How can that be a good thing? They seem dangerous to me, just because they are unique. Pedestrian activated traffic signals (regular red-yellow-green lights) are common in towns and cities in England, why not do that here?
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Aug 24, 2010 00:38
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Cichlidae posted:The article says they're safer, at least for now, but I'm not sure if that'll bear out. People are often dazzled by new things, but eventually get used to them and stop paying attention. I lived in Tucson when these started going up around the UofA, and used them often as both a pedestrian and a driver. I never noticed any taper off in obedience of them from either group, but then again it's been about six years now since I was driving around there on a regular basis. Choadmaster: A lot of the cost aspect seems like it could be made up in the parts you don't see. A regular signal needs the ME LOVE MAKE RED LIGHT box, sensor loops, and in any town bigger than two stoplights, some sort of coordination with the overall signal control system, whereas HAWK realistically just needs the poles and something only slightly more advanced than a dial timer. I suppose you could build the same simplicity with a green/yellow/red signal, though. The other nice perk is that stop phase - it basically just caters to impatient drivers by letting you not wait for a green light for old granny and her walker. With a traditional head and no extra signage, I wouldn't expect most AZ drivers to figure out a flashing red means stop, not stop and wait for green...keep in mind that if I'm driving to work around 9AM on US60 when the meters shut off, it takes about 10 minutes after the meters shut off before people realize they didn't just randomly break and actually just get on the freeway instead of stopping at the lights.
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Aug 24, 2010 00:39
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Choadmaster posted:2) Pressing a crosswalk button can activate a large blinking yellow signal head at either end of the crosswalk. That's less likely to be obscured by other traffic, but by the time you've gone that far why not spend a little extra money and put a real signal head on there? There's a new variety of these that we got to demo in the office last month. They have yellow strobe lights and, no joke, they're so bright it hurts. I could easily see them from the other end of the long hallway, 300 feet down, and they were casting a shadow on the wall behind me. Studies in a couple states have found that 90%+ of drivers stop for pedestrians with these, compared to ~10% with normal yellow flashers. We're installing one in West Hartford. Again, it could just be novelty, but we'll never know for sure unless we try them. (Also we want to see if Connecticut drivers will be as obedient as Floridians) Choadmaster posted:It's like they're different for the sole purpose of being different, because there's no actual functional reason behind it. How can that be a good thing? Sometimes great ideas start out as weird experiments. I'm obviously skeptical about their value, and I think that the concept could use some major refinement, but they seem to have saved lives, and that alone makes the installation worthwhile. Whether installing a conventional ped signal would have saved more remains to be seen. thelightguy posted:Or you could do what my town did and throw a pair of stop signs in the middle of the block, and assign two cruisers to sit on either side of the crosswalk ready to stop and ticket anyone who doesn't stop, roll back, and wait three seconds on the off chance that one of the two pedestrians who use that crosswalk (instead of the one at the end of the block) decide to cross. That kind of ticket revenue will pay for a full ped-actuated signal in just a couple days!
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Aug 24, 2010 00:40
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IOwnCalculus posted:I lived in Tucson when these started going up around the UofA, and used them often as both a pedestrian and a driver. I never noticed any taper off in obedience of them from either group, but then again it's been about six years now since I was driving around there on a regular basis. This is pretty much true. You can cut corners when making a signal just for pedestrians, though, so I'm sure their "half as much" estimate is a little optimistic. The REALLY expensive part of those signals is the directional audible pedestrian unit, which can go for as much as $80,000 per signal. Once you start putting those up, HAWK signal or no, you're really going to break the bank. quote:I suppose you could build the same simplicity with a green/yellow/red signal, though. The other nice perk is that stop phase - it basically just caters to impatient drivers by letting you not wait for a green light for old granny and her walker. With a traditional head and no extra signage, I wouldn't expect most AZ drivers to figure out a flashing red means stop, not stop and wait for green...keep in mind that if I'm driving to work around 9AM on US60 when the meters shut off, it takes about 10 minutes after the meters shut off before people realize they didn't just randomly break and actually just get on the freeway instead of stopping at the lights. Confusion causes accidents; giving drivers a decision to make increases the chances they'll crash. We really need to avoid any kind of ambiguity at all, which is why I'm happy to see that the City's giving out educational pamphlets with the water bills. The HAWK signals are up there, for better or for worse, so we may as well train drivers. I'm not sure how many minds it'll make an impression on, but it's a step in the right direction for sure.
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Aug 24, 2010 00:47
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Cichlidae posted:The REALLY expensive part of those signals is the directional audible pedestrian unit, which can go for as much as $80,000 per signal. Once you start putting those up, HAWK signal or no, you're really going to break the bank. What makes the audible system so expensive? Does it have to be heard at the same volume across the whole crosswalk? Again, I think the English system makes sense. At English crosswalk signals, you see a box like this:  The box contains a speaker, which is where the audible warning sounds. It's loud enough to be heard halfway across the street, at which point you should be able to hear the box on the other side. This solution can't be too expensive, and seems to work well in conjunction with standard signals.
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Aug 24, 2010 01:24
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IOwnCalculus posted:Choadmaster: A lot of the cost aspect seems like it could be made up in the parts you don't see. A regular signal needs the ME LOVE MAKE RED LIGHT box, sensor loops, and in any town bigger than two stoplights, some sort of coordination with the overall signal control system, whereas HAWK realistically just needs the poles and something only slightly more advanced than a dial timer. Exactly. The HAWK signal doesn't seem to do a drat thing a normal signal head couldn't. Except look different. IOwnCalculus posted:With a traditional head and no extra signage, I wouldn't expect most AZ drivers to figure out a flashing red means stop, not stop and wait for green... Granted this is the US and drivers here are absolute morons, but flashing red is a pretty standard signal mode that shouldn't confuse anyone. Plus, "people are stupid and may be easily confused by this standard signal" is hardly an argument in support of "so let's just install a mildly similar yet completely unfamiliar signal instead." I can see these HAWK signals somehow catching on like some horrible fad, and some day we'll be spending trillions of dollars to retrofit these things with proper signal heads just like we're having to reengineer all those damned cloverleafs. In 40 years Chichlidae's son (a hoverway engineer) will be beaming thoughts and imagery into our children's brains via the SomethingAwful hive mind: Here's some diagrams of those old-style HAWK things and here's the fuzzy logic we use to program the nanomachines that refabricate them into a standard signal head. No, I don't know what those traffic engineers of the early 21st were thinking, but hey isn't fixing this poo poo fascinating?
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Aug 24, 2010 01:27
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Kakairo posted:The box contains a speaker, which is where the audible warning sounds. It's loud enough to be heard halfway across the street, at which point you should be able to hear the box on the other side. This solution can't be too expensive, and seems to work well in conjunction with standard signals. It needs to be loud enough that you can hear both sides at once to give people an indication of which direction the "green light" is for. Around here it's usually a loud chirping alternating between one side and the other. Don't know why that needs to be so expensive though.
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Aug 24, 2010 01:30
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Choadmaster posted:I can see these HAWK signals somehow catching on like some horrible fad, and some day we'll be spending trillions of dollars to retrofit these things with proper signal heads just like we're having to reengineer all those damned cloverleafs. In 40 years Chichlidae's son (a hoverway engineer) will be beaming thoughts and imagery into our children's brains via the SomethingAwful hive mind: Here's some diagrams of those old-style HAWK things and here's the fuzzy logic we use to program the nanomachines that refabricate them into a standard signal head. No, I don't know what those traffic engineers of the early 21st were thinking, but hey isn't fixing this poo poo fascinating? Better yet, some by-product of manufacturing triangular signal backplates makes babies infertile, resulting in a total lack of kids 25 years down the line. Once it's figured out, there's a worldwide pogrom against traffic engineers. I live out the remainder of my grandchildless life in a gulag in downtown Phoenix. quote:Don't know why that needs to be so expensive though. Why do we pay $10,000 for a signal controller that's significantly less advanced than a pocket calculator? Same reason: there aren't many suppliers, and the technology is so specialized that they can charge whatever they want.
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Aug 24, 2010 02:14
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I entirely expect this to happen when CalTrans begins adding a carpool lane to the 405 through the Sepulveda Pass in Los Angeles. I am *barely* joking here. http://www.infrastructurist.com/2010/08/23/would-you-spend-nine-days-in-a-traffic-jam-these-drivers-did/ edit: oh they've already begun.  Look at those poor fools trapped in the background. They've been stuck there for a month now. Longpig Bard fucked around with this message at 05:55 on Aug 24, 2010 |
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Aug 24, 2010 05:46
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Bumming Your Scene posted:I entirely expect this to happen when CalTrans begins adding a carpool lane to the 405 through the Sepulveda Pass in Los Angeles. I am *barely* joking here. That's just cruel! We at least keep a lane open for every 1500 vph here in Connecticut. Hey, Dutch Engineer, would you mind emailing or PMing me? I'm working on an English translation to that roundabout program you showed me and I'd like some help.
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Aug 24, 2010 19:49
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Hey Cichlidae, I've been wondering about these marks ever since they put 'em down, which has been a while. Hell, I'm surprised they got 'em down at all - Flatbush Ave. (the 6-lane one) is just about the busiest street in Brooklyn. 1280x800 BrooklynBruiser fucked around with this message at 16:04 on Aug 25, 2010 |
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Aug 25, 2010 16:02
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First, awesome thread, read and enjoyed all of it. Second, next time you're stuck in traffic, it could be worse: http://online.wsj.com/article/SB10001424052748704125604575449173989748704.html?mod=WSJ_hpp_MIDDLETopStories 60 mile long traffic jam moving at 1/3 of a mile per day. "Yeah boss, I'm stuck in traffic. I'm not going to make it in until... next April." I guess this is the result of massive failure on the part of the traffic engineers involved?
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Aug 25, 2010 16:06
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BklynBruzer posted:Hey Cichlidae, I've been wondering about these marks ever since they put 'em down, which has been a while. Hell, I'm surprised they got 'em down at all - Flatbush Ave. (the 6-lane one) is just about the busiest street in Brooklyn. Maybe there is a four-way red light at some point, and the marks act as a crosswalk? I've seen stuff like that in other cities, though not at so large of an intersection.
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Aug 25, 2010 16:08
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Cichlidae posted:That's just cruel! We at least keep a lane open for every 1500 vph here in Connecticut. I don't have platinum, but if you give me your email adress I'll try to help you out 
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Aug 25, 2010 22:03
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Dutch Engineer posted:I don't have platinum, but if you give me your email adress I'll try to help you out Sure, it's something something. Hit me up. BklynBruzer posted:Hey Cichlidae, I've been wondering about these marks ever since they put 'em down, which has been a while. Hell, I'm surprised they got 'em down at all - Flatbush Ave. (the 6-lane one) is just about the busiest street in Brooklyn. I'm honestly not sure. It's not something I've seen before, and not in the Manual. It's most likely one of three things: - Used instead of cat tracks to lead cars across the offset intersection and into the proper lane - It's for bikes, to lead them to a bike lane. - Pedestrian scramble: Not as likely, because the standard design for a scramble would cost less to put in and be more obvious. BobTheJanitor posted:First, awesome thread, read and enjoyed all of it. One article I read said that the volumes there had been increasing 40% per year. Even in the worst times here, we had under 10%/year growth. There's almost no way you can handle 40% growth for multiple years without huge congestion, except for either massively overdesigning or constantly upgrading. And since roads are planned 20 years out, it would have been nearly impossible to forsee. The extra traffic, according to the article, was from a newly discovered coal field. You can't predict that stuff. Bold Robot posted:Maybe there is a four-way red light at some point, and the marks act as a crosswalk? I've seen stuff like that in other cities, though not at so large of an intersection. Have you seen markings like that? Ped scrambles generally have 4 crosswalks painted, or something that looks like a crate (the outlines of four orthogonal crosswalks and four diagonal). Cichlidae fucked around with this message at 22:41 on Aug 26, 2010 |
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Aug 25, 2010 23:12
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Crossposting this: http://11foot8.com/ This person's YouTube channel is nothing but trucks ramming into the same low bridge.
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Aug 25, 2010 23:41
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ijustam posted:Crossposting this: http://11foot8.com/ Haha I remember this bridge, it's right by East Campus. Street is busy as hell too because of all the traffic to the Brightleaf Square shops. The concept of a crash-only Youtube channel makes me chuckle.
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Aug 26, 2010 00:05
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ijustam posted:Crossposting this: http://11foot8.com/ Wonderful, I've never gotten to actually watch it happen! I only saw the aftermath of a trailer carrying structural trusses that hit a bridge and spilled them all over RI 146. Messiest one? Truck carrying hay bales. Crews came and swept the atomized hay off I-95.
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Aug 26, 2010 00:48
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ijustam posted:Crossposting this: http://11foot8.com/ in Westfield, MA we had a very similar problem. Route 10/202 went underneath a low railroad overpass. Happened all the time for almost a century. But it's being replaced as we speak. Thank God.
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Aug 26, 2010 01:42
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Looks like those lights detect tall vehicles to become activated.. how do they do that? https://www.youtube.com/watch?v=Z3yiRStQaHU
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Aug 26, 2010 06:18
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Cichlidae posted:I'm honestly not sure. It's not something I've seen before, and not in the Manual. It's most likely one of three things: Well, that's the thing - I've seen similar marks used for bike lanes, but there aren't any bike lanes in that part of Brooklyn. I guess it must be the offset intersection bit, I dunno.
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Aug 26, 2010 08:55
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Bumming Your Scene posted:Looks like those lights detect tall vehicles to become activated.. how do they do that? There's a detector up the road, usually a laser mounted between two posts, much like the ones used for burglar alarms. BklynBruzer posted:Well, that's the thing - I've seen similar marks used for bike lanes, but there aren't any bike lanes in that part of Brooklyn. I guess it must be the offset intersection bit, I dunno. Doesn't it look like there's one to the west of the intersection? The striping indicates a very narrow lane there, right at the end of the weird marking. Hard to tell from the aerial, but it appears to have a bicycle symbol, too.
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Aug 26, 2010 12:27
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Cichlidae posted:Doesn't it look like there's one to the west of the intersection? The striping indicates a very narrow lane there, right at the end of the weird marking. Hard to tell from the aerial, but it appears to have a bicycle symbol, too. I actually just walked by there on my way home today, and it is, in fact, a bike lane. Dunno how I never noticed it before.
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Aug 26, 2010 18:24
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Random but was driving through Iowa earlier this week (flooding,etc) and wondered - are there specific formulas for determining how much water/flow rate it takes to flush away an interstate? Are they designed to handle a certain amount of water coming across the road?
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Aug 27, 2010 01:07
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adaz posted:Random but was driving through Iowa earlier this week (flooding,etc) and wondered - are there specific formulas for determining how much water/flow rate it takes to flush away an interstate? Are they designed to handle a certain amount of water coming across the road? It depends on the current state of the road. One embankment might wash away because it was built on clay, the one next to it might be fine because it's all gravel. Bridges and culverts, though, are designed for specific flows. We design our bridges to let 50-year floods pass under the bridge with some freeboard, so it takes a 100-year storm or more to really damage them. Another critical factor is scour, which is when the water washes away all the sediment around the abutments and causes the bridge to collapse. The scour line is some distance below the streambed (it's the bottom of the footing, if I'm remembering correctly). If you're unfamiliar with what #-year storm means, it's a specific intensity/duration associated with a storm that recurs every # years on average. You'll get around 50 storms that produce the water level of a 2-year storm every century. Like any random event, though, you could get 3 2-year storms in a month, or none for a decade.
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Aug 27, 2010 01:58
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Cichlidae posted:It depends on the current state of the road. One embankment might wash away because it was built on clay, the one next to it might be fine because it's all gravel. Bridges and culverts, though, are designed for specific flows. We design our bridges to let 50-year floods pass under the bridge with some freeboard, so it takes a 100-year storm or more to really damage them. Another critical factor is scour, which is when the water washes away all the sediment around the abutments and causes the bridge to collapse. The scour line is some distance below the streambed (it's the bottom of the footing, if I'm remembering correctly). Does that depend on the length of the bridge? I mean, are all interstate bridges required to withstand a 50 year flood but longer/more critical bridges might be designed for bigger floods? I remember in 1993 during the huge floods in the midwest driving on the bridges over the Missouri/Mississippi where the water was hitting the bridge deck and that was way over 100 year flood levels. However the jist of what you're saying is the interstate isn't designed, at all, to withstand any specific amount of water or flow rate coming over it, it's only the culverts/bridges that might have specific codes.
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Aug 27, 2010 02:32
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adaz posted:Does that depend on the length of the bridge? I mean, are all interstate bridges required to withstand a 50 year flood but longer/more critical bridges might be designed for bigger floods? I remember in 1993 during the huge floods in the midwest driving on the bridges over the Missouri/Mississippi where the water was hitting the bridge deck and that was way over 100 year flood levels. Yeah. We try not to build things in flood plains, but there are always exceptions. Most bridges these days are built with 30- or 50-year lifespans, because it's assumed they'll either be functionally obsolete or structurally deficient at that point and need to be replaced. No point in designing a bridge to withstand that 500-year storm it'll never see, right? Also, remember that "interstate standard" means pretty much nothing in Connecticut. Most of ours were designed before interstates were designated, so they either don't meet standards or do by coincidence. I'm not saying that there aren't standards, just that I'm not familiar with most of them, because I've never built something to them and probably never will.
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Aug 27, 2010 02:43
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Cichlidae posted:Yeah. We try not to build things in flood plains, but there are always exceptions. Most bridges these days are built with 30- or 50-year lifespans, because it's assumed they'll either be functionally obsolete or structurally deficient at that point and need to be replaced. No point in designing a bridge to withstand that 500-year storm it'll never see, right? Fair enough, one of the big problems in Nebraska is a lot of the interstate bridges are hitting their lifetime limits and have to be replaced and nobody has the money to replace them. Since all these were "new" back when the interstate was being built I guess they have to be rebuilt to the standards or they aren't qualified for federal money. It's just kind of interesting - I'm sure in Connecticut the amount of bridges you have over interstates or interstate bridges that are over 50 years old you can probably count on one hand since they have either been replaced or expanded over the years. Out here I-80 is a lonely strip of pavement that hasn't been touched for decades other than the occasional resurfacing (and some parts have only been resurfaced once in 60 years). e: One of those things you'll never have to deal with but as an example it has taken 10 years to make I-80 between Lincoln and Omaha (About 45 miles, one major river) go from 2 lanes each way to 3. The state just doesn't have the money to spend on the huge costs it requires so they just have to slowly build it up, not like there is anything in the way but farmland. adaz fucked around with this message at 02:51 on Aug 27, 2010 |
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Aug 27, 2010 02:48
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adaz posted:It's just kind of interesting - I'm sure in Connecticut the amount of bridges you have over interstates or interstate bridges that are over 50 years old you can probably count on one hand since they have either been replaced or expanded over the years. Out here I-80 is a lonely strip of pavement that hasn't been touched for decades other than the occasional resurfacing (and some parts have only been resurfaced once in 60 years). You'd be surprised. The average age of a bridge here is 50 years. Of the big bridges, ones half a mile or more long, most have been replaced over the years, or at least heavily rehabilitated. The smaller ones, though, overpasses, culverts, and the like, are mostly original. We're starting to replace more and more due to age, but the interstates here haven't been expanded all that much since they were built. I-95 west of Branford (about half of it in the state), I-84 east of Hartford (half of it), and I-91 north of Hartford (again, half of it) have been expanded somewhat, but interstates 291, 384, 395, and 691 are almost entirely original, as well as most of our other freeways.
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Aug 27, 2010 02:57
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OK, can you explain the I-95 North to Rt 8 ramp in Bridgeport? It's a one lane exit that goes into a tight curve and comes out as two lanes on the overpass. It's like they decided, this bridge is wide enough to fit two lanes so we better have two lanes even if it makes no sense.
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Aug 28, 2010 01:53
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