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I mean, if you're going to do that, reduce the weaving by having one of these for an exit that forces a right merge into general traffic, followed by one for entrance a kilometre or two down the road that forces a left merge into the HOV lane. That would actually be pretty nifty, as a speed adjustment zone for changing between the two flows with less impact to the overall flow of traffic. That would make sense. As it is proposed now, you're having two groups of drivers trying to do both in the same lane. Varance fucked around with this message at 01:08 on Oct 17, 2021 |
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Oct 17, 2021 00:59
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Lobsterpillar posted:Judging from that diagram, they're creating more space by widening the shoulder, not taking up any currently existing road space. Now, you have 1) HOV to merge lane, 2) merge lane to HOV, 3) merge lane to normal, and 4) normal to merge lane. Plus, knowing how badly people drive normally around here, I can guarantee that people will use the merge lane as a passing lane in case traffic is slightly slower than they want it to be, and they'll go straight from the normal lane to the HOV lane in one go without looking. And since the HOV lanes aren't physically separated, they'll just drift in and out of them regardless of the marked exit and entry points. e.g. https://i.imgur.com/PJPHvyq.mp4
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Oct 17, 2021 16:33
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Chris Knight posted:On all the other HOV placements, you can either 1) go normal to HOV, or 2) go from HOV to normal lane. The HOV merge lane is an upgrade from "nothing, good luck lol" not an upgrade from fully-channelized movements. Fully channelized is the gold standard, particularly protected by concrete barrier. HOV merge lanes are for areas where you need to let people get in and out of the HOV faster than fully-channelized movements can work (you need to have minimum spacing on the order of 1/4 or 1/2 mile). Like you showed in your video, if you don't provide a formal way for someone to make a movement they need, they're more likely to cross the line in a completely unpredictable manner. Also in case it wasn't obvious, the earlier diagram of the HOV merge lane is not to scale. Its length is driven by the weaving analysis, design speed, assumed operating speed of travel lanes and HOV, etc... and probably wants to be 1/4 or 1/2 mile long itself. Chris Knight posted:On all the other HOV placements, you can either 1) go normal to HOV, or 2) go from HOV to normal lane. To reiterate, 5 mph -> 70 mph weaving is VERY unsafe. Assuming that your travel lanes are not congested is not valid for HOV implementations.
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Oct 17, 2021 17:35
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Again, the issue with channelised traffic is they usually don't put any shoulder on, so if there's a wreck rip, and if there's a wreck and no visibility, hello 100 car pileup due to black ice
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Oct 17, 2021 18:28
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Watermelon Daiquiri posted:Again, the issue with channelised traffic is they usually don't put any shoulder on, so if there's a wreck rip, and if there's a wreck and no visibility, hello 100 car pileup due to black ice Channelized traffic (like between concrete barriers) absolutely needs a shoulder if it's high speed - I'd argue that ignoring shoulders would be negligence for the engineer. The need for more width is one of the big constraints - when you put up physical barriers, you need more pavement so that you can get first responders past stopped traffic. Which means widening the road, which is Expensive(tm).
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Oct 17, 2021 19:20
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Devor posted:a carpool of slugs glaring at you from the passenger seat, Oh wow, that is a really interesting phenomenon.
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Oct 17, 2021 21:04
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https://www.youtube.com/watch?v=1OzC-LG9pG4 It's kind of like a baby's version of re-reading this thread, learning about different ways to build interchanges and stuff. Shame he didn't go further into real exchange designs beyon the cloverleaf but I got a giggle out of it anyway.
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Nov 1, 2021 22:30
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Devor posted:When an HOV is "working" properly, it can be moving 60mph faster than non-HOV lanes. The friction of folks getting in and out of the HOV lane causes the HOV performance (and safety) to drop drastically. It's a challenging problem to solve, but the merge lane you posted earlier is one method. Yeah having driven that road a week or two back the merge lane is a good idea. Physical barrier separation would be better probably, but this is a step in the right direction.
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Nov 1, 2021 23:19
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Yes, it's like a lava lamp.
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What if there's already somebody in the merge lane. Then you'd need a merge lane for your merge lane
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Nov 12, 2021 00:48
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Yo dawg
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Nov 12, 2021 01:01
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mobby_6kl posted:What if there's already somebody in the merge lane. Then you'd need a merge lane for your merge lane Collector/distributor lanes - a parallel set of 1 or more lanes, which keep the merging traffic separated from the mainline, separated by lane markings or (preferably) more concrete barrier. https://www.google.com/maps/place/I...67!4d-77.182044 You take the on-ramp and merge onto the C/D road, which mostly operates at freeway speeds but with higher friction due to people entering from 15-25 mph on- and off-ramps. Then you take one of the entrances to go from the C/D onto the mainline, this movement is lower friction than someone entering from an on-ramp, because they are already at freeway speeds.
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Nov 12, 2021 04:01
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Thanks for taking my dumbass question seriously  I think the whole thing looks weird because we don't have HOV lanes like that. Bus lanes are usually on the right.
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Nov 12, 2021 11:15
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mobby_6kl posted:I think the whole thing looks weird because we don't have HOV lanes like that. Bus lanes are usually on the right. We had a busy road that was used for numerous bus routes, it would get really congested during rush hour, so they decided to have the buses run on the shoulder, as a marked bus lane. It worked really well for a few weeks until the pavement on the shoulder just completely gave up from the heavy loads - it turns out that it wasn't a full depth shoulder, only partial depth, and huge ruts were created in the asphalt. The cheap solution became not-so-cheap when they had to fix all the shoulders.
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Nov 12, 2021 14:24
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Speaking of running on the shoulder... A few years ago, traffic lights were installed along an intersection near my home, including a light with a left-turn arrow, but no left-turning lane was added. Here's an old picture from Google Maps:  Recently, the road was repaved and the lines repainted, and there was still no left-turn lane created. People going straight just pass the turning car by driving on the right shoulder, which (IIRC) is legal in this state (PA), but I'm still surprised that the DOT added a turning light without a turning lane. Is this a totally normal thing that I've just never noticed before? (Meanwhile, two miles down the road is a gnarly 4-point intersection with left-turn lanes and regular traffic lights but no left-turn arrows, and the number of accidents that occur there is loving ridiculous -- in the past ten years, I personally have witnessed or seen the aftermath of dozens, and even the traffic lights themselves which sit on poles on the sidewalks have been knocked over dozens of times, too. Turning arrows would solve everything!  But the intersection just so happens to straddle the border line between two townships, so I assume nothing's been done because the townships can't decide who would be responsible.)
Rabbit Hill fucked around with this message at 16:06 on Nov 16, 2021 |
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Nov 12, 2021 16:53
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Rabbit Hill posted:Speaking of running on the shoulder... "It depends". If it's a relatively low volume left turn, you really would prefer not to stripe the turn lane separately, and run all the through traffic on the shoulder. The only difference between the pre-arrow configuration, and the post-arrow configuration, is that the arrow lets a couple folks through at the beginning (or end) of the green phase, instead of 0 at the beginning, or just 1 at the end. If you remove the arrow, you will still get turners queuing up and blocking the through lane, making everyone else go around on the shoulder. There was a similar case here where they added a left green arrow, but didn't adjust striping, and since it was a moderately high volume turn, it didn't improve operations because everyone queued into one big line. I wrote in to the county DOT, and they fixed it a few weeks later by fixing the striping. Devor fucked around with this message at 17:16 on Nov 12, 2021 |
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Nov 12, 2021 17:09
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Devor posted:We had a busy road that was used for numerous bus routes, it would get really congested during rush hour, so they decided to have the buses run on the shoulder, as a marked bus lane. It worked really well for a few weeks until the pavement on the shoulder just completely gave up from the heavy loads - it turns out that it wasn't a full depth shoulder, only partial depth, and huge ruts were created in the asphalt. Usually the bus lanes are normal lanes, not shoulders or anything, but they get ruined pretty quickly anyway, especially near the stoplights, sharp turns or bus stops. It's not like it's unexpected so I've no idea why they don't just drop a concrete plate in those places.
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Nov 12, 2021 19:23
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Rabbit Hill posted:Speaking of running on the shoulder... Can't speak to the specific laws but it's possible that it's illegal to pass a MOVING vehicle. A car stopped to turn right isn't moving. I think it's a bit odd and am a little confused as to why there even is a left turn arrow of they haven't put a lane in. Is this a particularly high risk location with significant site constraints that they couldn't widen the carriageway to accommodate another lane? It doesn't look like it. quote:(Meanwhile, two miles down the road is a gnarly 4-point intersection with left-turn lanes and regular traffic lights but no left-turn arrows, and the number of accidents that occur there is loving ridiculous -- in the past ten years, I personally have witnessed or seen the aftermath of dozens, and even the traffic lights themselves which sit on poles on the sidewalks have been knocked over dozens of times, too. Turning arrows would solve everything! Sounds like they can't decide who's going to pay for it, and it's possibly pretty costly. Turning arrows would probably fix a few problems, but might also cause longer queues /delays (for those who are concerned about that sort of thing), and there might be other things that need doing at that intersection. Sounds like speed is also a problem - does the US used raised platforms at intersections to slow approach speeds? Somebody fucked around with this message at 17:23 on Nov 16, 2021 |
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Nov 13, 2021 02:14
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Lobsterpillar posted:Sounds like speed is also a problem - does the US used raised platforms at intersections to slow approach speeds? It sounds like youre not from the US so Ill be gentle. Raised intersections are a horrible idea because people would intentionally jump them in their lifted pickups while trying to make the biggest possible exhaust cloud. It might work in a civilized country.
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Nov 13, 2021 03:52
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Rabbit Hill posted:Speaking of running on the shoulder... What's the speed limit and traffic level on that road? As an urban dweller it seems perfectly natural to not have a seperate turning lane if the traffic level is low. And the correct movement for drivers behind them is not to drive on the shoulder but just to wait their turn. If the traffic level is high then sure put a seperate turn lane in (or better still a traffic circle) but I don't exactly blame the municipality for not wanting to shell out for that. Somebody fucked around with this message at 17:23 on Nov 16, 2021 |
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Nov 13, 2021 04:24
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Lobsterpillar posted:Sounds like speed is also a problem - does the US used raised platforms at intersections to slow approach speeds? There are a handful of intersections like that here (as a result of hamfisting side streets onto very convex existing highways that should loving not have side streets turning onto them); They are the most horrid intersections to deal with in the entire city, and can snarl everything for a quarter mile when poo poo gets real on a holiday weekend, as everyone has to do 10 in a 35 to handle an otherwise simple green light
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Nov 13, 2021 04:28
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PittTheElder posted:What's the speed limit and traffic level on that road? As an urban dweller it seems perfectly natural to not have a seperate turning lane if the traffic level is low. And the correct movement for drivers behind them is not to drive on the shoulder but just to wait their turn. It's posted 45 mph, and holy poo poo I just checked the volumes, and it gets 17k AADT, that's a lot higher than I was expecting.
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Nov 13, 2021 04:28
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Devor posted:It's posted 45 mph, and holy poo poo I just checked the volumes, and it gets 17k AADT, that's a lot higher than I was expecting. Well that explains why it's got an arrow. A 90 degree crash at that sort of speed will probably kill someone so it's likely an attempt to prevent that. With that sort of volume it's even more baffling that it doesn't have a turning lane (although I guess at 45mph a nose to tail is probably only going to seriously injure you and write off the car(s)... Unless of course it shunts you into oncoming traffic.)
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Nov 14, 2021 06:07
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https://twitter.com/fietsprofessor/status/1459885366966685698 https://twitter.com/fietsprofessor/status/1459896455645253633
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Nov 15, 2021 08:48
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I'm still looking at the no pedestrian crossing signs in all directions. I know PA tries to make walking as suicidal as possible, but yeesh.
Varance fucked around with this message at 01:22 on Nov 17, 2021 |
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Nov 17, 2021 01:20
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I get the idea of reducing cars, I disagree with the proposals of replacing all major roads with canals.
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Nov 17, 2021 02:09
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That is not "all major roads", it was one pointlessly large highway in the city center where everything is within walking/cycling distance. We still have major ring roads, just not major roads that allow you to cross a city from one side to the other through the center at high speed.
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Nov 17, 2021 04:48
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SlothfulCobra posted:I get the idea of reducing cars, I disagree with the proposals of replacing all major roads with canals. It was originally a canal before it was a road so they just returned it to that
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Nov 17, 2021 04:53
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Entropist posted:We still have major ring roads... Just for context, among those is a very tight highway/freeway ring with a 2019 AADT of more than 200k on three sides. Even by North American standards, that's pretty heavy, and in general pretty ludicruous for a metro of ~1 million. Shows how you can get rid of the stupid inner city roads, even when having to facilitate traffic a bit further out IMO.
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Nov 17, 2021 12:41
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I'm a fan of the tunnel solution like what they did in Düsseldorf: So you can still get through without clogging up surface streets and creat a lot of pleasant public space. Prague has a huge road straight through the center that could benefit from such a makeover too. 
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Nov 17, 2021 13:10
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They are also trying to do this here with various ring roads (A9 in Amsterdam Bijlmer, A10 at the south station in Amsterdam, and the highway in the south of Groningen) but they tend to be behemoth projects that always go massively over budget and over time, so public support for such things is dropping rapidly. They also did it in Maastricht with the main highway to Belgium that went close to the center. Bicycle Dutch has a post on it, this is how it looks now on top: https://bicycledutch.wordpress.com/2019/10/16/the-a2-motorway-no-longer-divides-maastricht/. That one was pretty successful although it also took ages. I guess the geography is a bit more favourable there (it's not a swamp).
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Nov 17, 2021 17:42
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I mean it shouldn't really be a surprise that trying to put a motorway underground in one of the most expensive neighbourhoods in the entire country is going to cost a fair bit of cash. And if you then put a hard ceiling on bid price it also shouldn't be a surprise that everything that isn't absolutely essential is stripped out of the plans just to make it come in under that ceiling.
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Nov 17, 2021 18:14
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mobby_6kl posted:I'm a fan of the tunnel solution like what they did in Düsseldorf: Uhg I hate that road. Just a big ol elevated freeway/stroad right through your city core and ruining your amazing historic train station.
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Nov 17, 2021 22:52
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mobby_6kl posted:I'm a fan of the tunnel solution like what they did in Düsseldorf: They did something similar in my home town, starting 20 years ago and wrapping a few years later. In hindsight, IMO it has been extremely valuable. The former freeway is now a walkable two-lane street, and has a tram line running down its middle. The area between the road and the river are now accessible to pedestrians, and the area has been actively developed for 15 years rendering some quite nice park area by the water. (Also some hotel highrises...)
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Nov 18, 2021 14:45
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NJB gets a video up just in time for the above discussion. https://www.youtube.com/watch?v=d8RRE2rDw4k
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Nov 20, 2021 17:26
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Something about this side by side merge is just amazing.
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Dec 2, 2021 03:11
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mamosodiumku posted:Something about this side by side merge is just amazing. Looks like the tunnel splits in half midway, which is why one of the merges is opposite the typical direction. No passing in the tunnel, so you have to get in your lane before the tunnel.
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Dec 2, 2021 03:45
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mamosodiumku posted:Something about this side by side merge is just amazing. Everything goes fucky when you have to plan around reversible lanes
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Dec 2, 2021 17:47
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Devor posted:Everything goes fucky when you have to plan around reversible lanes Reversible lanes are one of those ideas that just creates far more problems than it solves. Removing them and changing nothing would certainly be an improvement, and would probably reduce congestion at the same time.
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Dec 2, 2021 22:41
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Kaal posted:Reversible lanes are one of those ideas that just creates far more problems than it solves. Removing them and changing nothing would certainly be an improvement, and would probably reduce congestion at the same time. That one is apparently at a tunnel, which, along with long bridges, is probably the one reasonable use case for having reversible lanes. When the eastbound lanes on the Bay Bridge are closed for an accident/construction work, you need a way to make the diversion not take an hour and a half.
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Dec 2, 2021 23:06
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mamosodiumku posted:Something about this side by side merge is just amazing. This reminds me of the 10/100 interchange outside of Annapolis in Maryland. Two heavily trafficked roads and lots of loving weaving Here. D34THROW posted:This. This loving poo poo. Every time I was on this stretch of highway, I bitched about it.
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Dec 2, 2021 23:28
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