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I wonder if the LED traffic lights are living up to their promise... I was in a town in CT the other day where nearly every light had > 50% of the LEDs out. Maybe they just got a bad batch, but that seems like an expensive fix job. I can't imagine the LED head units were that old.
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Aug 13, 2012 15:27
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That's crazy. Almost all the traffic lights and signals where I live are LED's and I've never seen any out. lovely low-bid quality?
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Aug 13, 2012 15:30
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Baronjutter posted:That's crazy. Almost all the traffic lights and signals where I live are LED's and I've never seen any out. lovely low-bid quality? lovely maintenance is a possibility too. I've seen traffic lights where about 20% of the LEDs were clearly dead, but it's pretty rare for me to see that.
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Aug 13, 2012 16:15
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smackfu posted:I wonder if the LED traffic lights are living up to their promise... I was in a town in CT the other day where nearly every light had > 50% of the LEDs out. Maybe they just got a bad batch, but that seems like an expensive fix job. I can't imagine the LED head units were that old. Isn't it a lot better to have the light 50% out instead of 100% out like when a normal traffic light burns out? A standard traffic light bulb will last somewhere around 8,000 to 16,000 hours illuminated, while each LED inside an LED traffic light array will last between 40,000 and 100,000 hours illuminated. So let's assume we have an example set of traffic lights at this one intersection, both facing the same direction of travel and operating on the same timing, but one is LEDs and the other is incandescents. The timing for this particular facing is 30 seconds green, 5 seconds yellow, 25 seconds red. On the incandescent signal: The green bulb should last about 1.8 to 3.6 years The yellow bulb should last 10.9 to 21.9 years (realistically, something else is probably going to cause it to break before it burns out) The red bulb should last 2.2 to 4.4 years On the LED array signal: The green array should last about 9.1 to 22.8 years before all the LEDs burn out The yellow array should last about 54.7 to 136.9 years before all the LEDs burn out (again, something else is probably going to break or remove that signal well before it breaks on its own) The red array should last about 10.9 to 27.4 years before all the LEDs burn out Now, of course, the LEDs in the LED signal won't all go at once, they'll slowly burn out over time until you end up with not enough illumination to be safe and you install new ones in there. On the whole though, the LED arrays are going to last between 2.5 times to 12.5 times longer (respectively, best incandescents versus worst LEDs and worst incandescents versus best LEDs). And the LEDs might be independently vulnerable to other types of damage besides straight wear and tear. Perhaps that town had them poorly wired so the LEDs got shorted out quickly, or has power supply problems that cause them to be exposed to dangerously over or under volted conditions.
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Aug 13, 2012 16:17
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Install Gentoo posted:Isn't it a lot better to have the light 50% out instead of 100% out like when a normal traffic light burns out? Yes, but it also allows for poor municipal policies to rear their heads. Like you can't skimp on replacing bulbs, but apparently you can skimp on when you fix up LEDs. Especially if replacement cost is high and there isn't money in the budget. And if they are failing faster than expected, now that introduces blame and "who is going to pay for this" and all that junk. (For the record, it was in Cromwell on 372 heading East towards Rt 9, near Rookies.)
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Aug 13, 2012 17:03
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I like how some departments go to flash mode during the early morning. I bet that saves 50% in power going to the signals that are flashing. I believe they just shut the ped signals down too. Makes driving way more efficient at night if you plan your route through a bunch of yellow flashers.
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Aug 13, 2012 20:11
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smackfu posted:I wonder if the LED traffic lights are living up to their promise... I was in a town in CT the other day where nearly every light had > 50% of the LEDs out. Maybe they just got a bad batch, but that seems like an expensive fix job. I can't imagine the LED head units were that old. Our red LEDs are much older than the yellow and green ones, and they are based on older technology, with shorter lifespans. We have an LED re-lamping job to replace them all, but we don't have the money to make it happen. As it stands, they use significantly less electricity than incandescents, so even if they broke after a year, we'd still be making money. And the fact that they break one at a time, rather than all at once like an incandescent, means that the consequence of leaving them up past their intended lifespan are much less severe. Pretty sure they do last longer than incandescents, though. At least the new ones.
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Aug 13, 2012 21:39
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grillster posted:Makes driving way more efficient at night if you plan your route through a bunch of yellow flashers. The cost of a remotely possible horrible accident while you go 65 through yellow flashing lights has gotta be factored into that too.
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Aug 13, 2012 23:39
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Mandalay posted:The cost of a remotely possible horrible accident while you go 65 through yellow flashing lights has gotta be factored into that too. If you leave lights running colors at night, you'll end up with more people running red lights, and delays will be higher overall. There used to be a major electricity cost savings to flashing operation, but now that we're using LEDs, you may save one kWh per night. Even here, where electricity is the most expensive in the continental US, that's not a lot of money.
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Aug 14, 2012 00:20
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Cichlidae posted:If you leave lights running colors at night, you'll end up with more people running red lights, and delays will be higher overall. There used to be a major electricity cost savings to flashing operation, but now that we're using LEDs, you may save one kWh per night. Even here, where electricity is the most expensive in the continental US, that's not a lot of money. Oh, so flashing lights are safer too? the more you know!
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Aug 14, 2012 00:24
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Reducing unnecessary stopping, waiting and driving away means less energy used driving. A car cruising through an intersection at 40 MPH at 3 AM put up against the same car slowing to wait for a signal will have covered the same distance more efficiently. Sounds good to me: Reduction in noise from cars reacting to the light Time not used waiting by the driver Less electricity used, even if perceived as small on a local scale
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Aug 14, 2012 00:45
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Keeping with the LED discussion.. depending on how the LEDs are wired and what kind of power supply is driving them you can get a condition called thermal or current runaway.. (http://ledsmagazine.com/features/6/2/2) For example, a string of LEDs wired in parallel being driven by a constant current power supply. If one LED fails, the current flowing through the other LEDs increases, another LED pops, current increases again, and so on until all have failed from being over driven. There are several ways to prevent runaway. But I can imagine a manufacturer not doing any of them though just to save a penny.
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Aug 14, 2012 04:28
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stevewm posted:There are several ways to prevent runaway. But I can imagine a manufacturer not doing any of them though just to save a penny.
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Aug 14, 2012 05:47
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grillster posted:Reducing unnecessary stopping, waiting and driving away means less energy used driving. A car cruising through an intersection at 40 MPH at 3 AM put up against the same car slowing to wait for a signal will have covered the same distance more efficiently. I hope these junctions people are cruising through at 40 have absolutely incredible visibility but yeah, there must be a fairly sizeable effect on emissions.
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Aug 14, 2012 07:32
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Jonnty posted:I hope these junctions people are cruising through at 40 have absolutely incredible visibility but yeah, there must be a fairly sizeable effect on emissions. We set all of our signals so that no two conflicting through movements will get flashing yellow. The major movements (north + south, for example) will get flashing yellow, and the side street (east + west) will get flashing red. This is treated as a two-way stop. As long as there is adequate sight distance from the stop bar on the side street, there is a very limited potential for crashes.
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Aug 14, 2012 12:17
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Cichlidae posted:We set all of our signals so that no two conflicting through movements will get flashing yellow. The major movements (north + south, for example) will get flashing yellow, and the side street (east + west) will get flashing red. This is treated as a two-way stop. As long as there is adequate sight distance from the stop bar on the side street, there is a very limited potential for crashes. I don't think I've ever seen flashing red? Is this a US thing or have I just not been on the right kind of roads?
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Aug 14, 2012 12:21
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We only flash yellow here in the NL and let the secondary signs and roadmarkers do their work.
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Aug 14, 2012 12:23
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I ran into an interesting situation a few weeks ago. Pretty busy intersection between two state routes. I guess the traffic light power was out or something, so they put up temporary stop signs. But then the power came back, so both the stop signs and the traffic light were working. Pretty much the most dangerous intersection I can imagine. Some people are only going to see the traffic light, others are going to see both and stop and go, and you hope they don't run into each other.
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Aug 14, 2012 13:32
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Munin posted:I don't think I've ever seen flashing red? Is this a US thing or have I just not been on the right kind of roads? It's the only way I've ever seen flashing lights work in the US. There are no well defined right-of-way markers or rules for signaled intersections where the lights are completely out. This, of course, leads to a giant shitshow when power is lost and intersections go completely dark.
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Aug 14, 2012 15:07
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kapinga posted:It's the only way I've ever seen flashing lights work in the US. There are no well defined right-of-way markers or rules for signaled intersections where the lights are completely out. This might just be where I live but a lot of streets don't go to flashing beyond some small side streets. When the power goes out on the main streets they do go flashing and holy gently caress do people have no idea what to do anymore! One car will stop at the yellow and the guy next to him will go on through, the cars stuck on the red will try and squeeze out in moving traffic and it's all just a clusterfuck.
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Aug 14, 2012 15:12
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kapinga posted:It's the only way I've ever seen flashing lights work in the US. There are no well defined right-of-way markers or rules for signaled intersections where the lights are completely out. Don't you have a "right before left" rule like in Europe or similar? In the UK the right of way is shown by road markings at the intersection.
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Aug 14, 2012 15:17
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If the signalized intersection is completely dark it should be treated as an all way stop sign in the US.
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Aug 14, 2012 15:32
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grillster posted:If the signalized intersection is completely dark it should be treated as an all way stop sign in the US.
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Aug 14, 2012 15:38
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Jethro posted:While this is true, this relies on people seeing that there are malfunctioning signals, remembering what to do from driver's ed, knowing how an all-way stop works, and being courteous enough to actually stop even when the cross street is some dinky side street that normally gets the signal every 5 minutes. That's not even getting into the fact that at least some intersections were signalized for a reason.
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Aug 14, 2012 15:49
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Opals25 posted:When the power goes out on the main streets they do go flashing and holy gently caress do people have no idea what to do anymore! Traffic tends to run through intersections at about the same pace when we lose power. Everyone just four-ways it, and lets fleets across at each turn. Lots of our poles also have fold-out stop signs in case of extended outage.
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Aug 14, 2012 15:50
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The really painful ones are where a 6-way intersection goes dark. It's like a free-for-all where half the people just close their eyes and hit the gas.
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Aug 14, 2012 16:01
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Munin posted:Don't you have a "right before left" rule like in Europe or similar? In the UK the right of way is shown by road markings at the intersection. Yeah, we don't have markings like that. Pretty much every signalized intersection is just going to have a solid white stop bar. The lights then control who has right of way when. The other posters are correct that "lights out" means all-way stop, but if it involves one or more major streets, you're gonna be in for a fun time. If it's a simple 4-way stop with one lane in each direction, people will generally know how to handle it (first one to the intersection gets right-of way, and if anyone else can go without obstructing them, they probably will). The problem comes in where you have one or more major roads (2+ lanes in each direction), since almost no one encounters a stop sign on a road that large. Then you get a disastrous mix of people who treat it as a stop and people who try to treat the major road as flashing yellow (i.e. they have right of way). Chaos Motor posted:Traffic tends to run through intersections at about the same pace when we lose power. Everyone just four-ways it, and lets fleets across at each turn. Lots of our poles also have fold-out stop signs in case of extended outage. Jeez, where do you live that they have so many power outages to actually need signs? And that traffic is basically unfazed by the loss of signals? I live in hurricane country (where extended power outages can happen), and we definitely don't bother with fold-out signs.
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Aug 14, 2012 16:04
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grillster posted:If the signalized intersection is completely dark it should be treated as an all way stop sign in the US. True, assuming that drivers: a) see the dead lights b) know to stop if they do see them c) aren't a raging rear end in a top hat in a F350 Supercab Longbed Dually with a v8 Diesel Hemi It's strange how a combination of a+b+c fails to happen as often as not.
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Aug 14, 2012 16:06
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kapinga posted:Jeez, where do you live that they have so many power outages to actually need signs? And that traffic is basically unfazed by the loss of signals? I live in hurricane country (where extended power outages can happen), and we definitely don't bother with fold-out signs. Kansas City, where ice storms leave 2" thick coatings on every hanging cable every winter, and lightning storms blow up dozens of transformers every summer.
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Aug 14, 2012 17:19
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Munin posted:Don't you have a "right before left" rule like in Europe or similar? In the UK the right of way is shown by road markings at the intersection. We get a couple meters of snow per year, so designating anything entirely through pavement markings is a bad idea. Blizzards tend to knock out the power, too, which leaves you in a horrible situation.
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Aug 14, 2012 23:11
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kapinga posted:Jeez, where do you live that they have so many power outages to actually need signs? And that traffic is basically unfazed by the loss of signals? I live in hurricane country (where extended power outages can happen), and we definitely don't bother with fold-out signs.
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Aug 14, 2012 23:36
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DTurtle posted:Here in Germany every intersection with traffic lights also has normal right of way traffic signs. At night, main routes have the traffic light turned off, while the side routes have flashing yellow. This is just to add warning for the side routes. What counts are the signs. Here in the united states, if the lights are out, drivers will naturally assume that the world has ended and we are now embroiled in a post-apocalyptic fantasy where only the strong may survive unto the far side of the intersection. I mean, technically it's supposed to be a four way stop, but those are rules of the dimly remembered past before the lights went out, and we can scarcely be expected to follow those nebulous "rules" of the forgotten before-time at the expense of being delayed from picking up our kids at soccer practice by even four seconds. Americans are basically the worst drivers in the entire world, is what I'm saying.
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Aug 15, 2012 02:25
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On I-287 SB in New Jersey, there's a split into express / local lanes right before the interchange with 206, then exits attached to the left side of the express and the right side of the local lanes, and then the lanes reunite. This seems very silly. Is there a reason to make an express/local split for one exit, or would this more likely be part of an expansion that never went further?
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Aug 15, 2012 02:48
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My neighborhood used to be full of 4-way intersections with no signage and no clear right-of-way. Legally, intersections like this are all-way stops. In practice, though, they were no-way stops, and even with everyone familiar with them and fully aware of the risks, they were a constant cause of accidents until the city finally relented and put in stop signs.
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Aug 15, 2012 02:48
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grover posted:My neighborhood used to be full of 4-way intersections with no signage and no clear right-of-way. Legally, intersections like this are all-way stops. In practice, though, they were no-way stops, and even with everyone familiar with them and fully aware of the risks, they were a constant cause of accidents until the city finally relented and put in stop signs.
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Aug 15, 2012 03:59
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NightGyr posted:On I-287 SB in New Jersey, there's a split into express / local lanes right before the interchange with 206, then exits attached to the left side of the express and the right side of the local lanes, and then the lanes reunite. This seems very silly. Is there a reason to make an express/local split for one exit, or would this more likely be part of an expansion that never went further? The split actually starts at the interchange with 78, which is a weird one itself. If you're getting on southbound I-287 from westbound I-78, the ramp comes in on the left side of one of the split carriageways, while if you're coming from eastbound 78 ad going to southbound 287 the ramp comes in on the right side of the other carriageway. So each carriageway needs its own exit to 206/202, and I guess it would be unsafe to have a single carriageway with 78 traffic coming in from both sides at once. It's the same situation going from northbound 287 to east or west bound 78, the road splits, and in one direction you have a left exit, and in the other a right exit. And to accommodate that, 202/206 have two exits to get onto the northbound 287.
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Aug 15, 2012 04:14
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Install Gentoo posted:The split actually starts at the interchange with 78, which is a weird one itself. If you're getting on southbound I-287 from westbound I-78, the ramp comes in on the left side of one of the split carriageways, while if you're coming from eastbound 78 ad going to southbound 287 the ramp comes in on the right side of the other carriageway. So each carriageway needs its own exit to 206/202, and I guess it would be unsafe to have a single carriageway with 78 traffic coming in from both sides at once. Speaking of US 202, what a bizarre road that is. US 2 goes from Maine to Washington, with a big gap where it goes through Canada. Normally, major East-West US routes are numbered as multiples of 10, but the Feds weren't keen on having a Route 0, so they numbered it 2 instead. Despite being a "major" road, it's mostly a two-lane rural road, really unremarkable. US 202, as the number implies, is a minor branch of US 2. It goes from Maine to Delaware. For its first few hundred miles, all throughout New England, 202 is a rural two-lane road like its parent. It's a relatively new designation in New England's history, since most of the other Federal routes were signed as New England Interstates before the Feds took hold in the 1930s. In Connecticut, the 202 designation is just an afterthought, as it's either designated in concurrency with other routes (US 7, US 44, CT 10) or replacing old state roads. Then, you get into New Jersey, and 202 is a BIGSHOT FREEWAY. Where the hell did that come from? 202 is a rural road subservient to another rural road, approaching its terminus, and suddenly it's important. Like some kind of highway Cinderella.
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Aug 15, 2012 11:26
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Cichlidae posted:Speaking of US 202, what a bizarre road that is. US 2 goes from Maine to Washington, with a big gap where it goes through Canada. Normally, major East-West US routes are numbered as multiples of 10, but the Feds weren't keen on having a Route 0, so they numbered it 2 instead. Despite being a "major" road, it's mostly a two-lane rural road, really unremarkable. Because 202 and 206, each in their own filled with congestion, decide to combine like the voltron of traffic jams and create a road that's really just an utter PITA.
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Aug 15, 2012 14:37
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potato of destiny posted:Here in the united states, if the lights are out, drivers will naturally assume that the world has ended and we are now embroiled in a post-apocalyptic fantasy where only the strong may survive unto the far side of the intersection. I mean, technically it's supposed to be a four way stop, but those are rules of the dimly remembered past before the lights went out, and we can scarcely be expected to follow those nebulous "rules" of the forgotten before-time at the expense of being delayed from picking up our kids at soccer practice by even four seconds. Man, where do you live? Throughput tends to IMPROVE when we lose signaled intersections, probably because everyone gumptions-up and says "Well the system's hosed, it's up to us now" and everyone pulls together and drives in an orderly fashion instead of the every-man-for-himself free-for-all we normally have. I would say we do have the worst drivers ever - until the lights go out. What a weird inversion.
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Aug 15, 2012 15:10
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Cichlidae posted:Then, you get into New Jersey, and 202 is a BIGSHOT FREEWAY. Where the hell did that come from? 202 is a rural road subservient to another rural road, approaching its terminus, and suddenly it's important. Like some kind of highway Cinderella. Well that's the only part of its route, aside from the other freeway 202 segment in Pennslyvania, where the route it takes is actually useful for commuting and such. Instead of being mostly a meandering road to nowhere in particular like the rest.
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Aug 15, 2012 16:55
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