Behold, the 360-degree freeway onramp! http://maps.google.com/maps?q=san+f....00284&t=h&z=19 (with a parking lot in the middle of it of course)
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# ¿ Aug 1, 2009 02:50 |
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# ¿ Mar 28, 2024 11:31 |
Cichlidae posted:Yep, the loop is necessary to gain the elevation to get to the second deck of the freeway!
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# ¿ Aug 1, 2009 03:17 |
Green arrows mean the same thing and are less confusing, so why?
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# ¿ Aug 3, 2009 02:07 |
I pity anyone who lives on treasure island because fuuuuuck http://maps.google.com/maps?f=q&sou...002401&t=h&z=19 There's about 10 car-lengths between the stop sign and a merge with 50+ mph traffic (as high as 70 sometimes). Fuuuuuck!
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# ¿ Aug 3, 2009 16:30 |
Dominus Vobiscum posted:That's an odd one, given that they're trying to reduce the amount of text on signs. I can't imagine it'd be used anywhere other than intersections with a history of right-turning vehicles running into people making u-turns. Why not just prohibit u-turns instead? Sometimes people need to make u-turns! (roads with medians and they need to enter a driveway on the opposite side).
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# ¿ Aug 4, 2009 02:22 |
Berkeley, california has something which is kind of like a fused grid or new urbanist design but a little simpler: It was originally built with a plain old grid, but afterwards, they blocked off certain movements to cars (only cars, bicycles can still use them). To a pedestrian, it's pretty much indistinguishable from a regular grid, but from a driver's perspective, it's much more like a hierarchy or fused grid.
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# ¿ Aug 8, 2009 19:44 |
Cichlidae posted:What method do they use to block motorists? Are there barriers, curbs, and grass, or do they just put up turn restriction signs and pavement? Obviously, the former is much nicer, and in areas that have already been built up, it seems like a great way to encourage other modes of transportation and lower speeds on minor roads. here's an example
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# ¿ Aug 8, 2009 20:12 |
Minister Robathan posted:One thing I've always wondered about stack interchanges, specifically 4-level stacks, is why they make everything cross at the centre, instead of spreading the ramps out (provided there's enough room). Like in this case, it *seems* that it would be cheaper to not have all the ramps cross directly at the centre, in order to cut down on the height required. The difference in cost might actually be marginal compared to the cost of the enlarged footprint, but I was wondering if there's any specific reason that it's done in this way. Someone posted a "three level stack" (I forget what they called it) early, which looks kind of like a spiral.
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# ¿ Aug 11, 2009 09:38 |
Ah here it is:Cichlidae posted:
What I don't get is why one pair of turning ramps is underneath the straight-through roads. It would make sense to me for both sets of turning ramps to go above, and the straight-through to stay level, since gravity would help you with your deceleration and acceleration. Socket Ryanist fucked around with this message at 09:52 on Aug 11, 2009 |
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# ¿ Aug 11, 2009 09:40 |
Cichlidae posted:One funny thing about this interchange that you may have noticed: the West to East through lanes exit from the right. Any guesses as to why this happened? Either that, or it has something to do with that lone, out-of-place looking building which looks like it would be in the way of making the through lanes stay on the left.
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# ¿ Aug 11, 2009 14:57 |
Calast posted:OP, thank you so much. This thread has been amazingly fascinating, and I'm learning compassion for the people who have to deal with fixing such amazing SF Bay Area traffic nightmares as: They should just make it a four-way stop like the similar Central exit further up north. A roundabout would make more sense but that costs $$$, a couple extra stop signs would do a BIG help and not cost $$$ Re: wrong-way multiplexes, in the san fernando valley they just sign "Ventura fwy east, ventura fwy west" rather than 101 north/south (ventura fwy is also 138 I think?)
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# ¿ Aug 15, 2009 11:18 |
There's a big party venue I go to that has three dancefloors, a coat check, bathrooms and the main entrance all connected by a rotunda, which turns into a giant traffic jam as people are moving around. I've suggested to several people putting a pole in the middle and telling people to walk counterclockwise.
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# ¿ Aug 17, 2009 00:31 |
Samurai Sanders posted:Another question you may not be able to answer: why would a road construction crew ever do their work right in the middle of a very busy street, right in the middle of the Goddamned day? Because it's been going on for months now on my way to work. Why not do the work at night, like they usually do on the highways?
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# ¿ Aug 19, 2009 10:45 |
Wikipedia says that campus used to be an air force base, so I would guess that red line is a former runway
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# ¿ Aug 19, 2009 22:10 |
Lobstaman posted:Why not put a barrier toll on the wee bit of I-684 that passes through Greenwich, where there are no on or off ramps for CT drivers.
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# ¿ Aug 21, 2009 23:43 |
nm posted:No, most states don't have this. Most states make it a standard strict liablity crime to do over XX mph.
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# ¿ Aug 30, 2009 02:25 |
Does anyone besides california have the magic "Sometimes I'm a lane and sometimes I'm parking!" lanes that we do? Do these actually help?
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# ¿ Sep 1, 2009 02:02 |
Choadmaster posted:I should note that there is an upper limit to the 85th percentile rule; I think it's 55 MPH. Anything more than that they get to set wherever they please.
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# ¿ Sep 6, 2009 21:56 |
Well regardless of the default speed limit you also have to follow the Basic Speed Law -- don't drive at an unsafe speed. Posting a speed limit sign won't help you much because, in california, speed limits below 55 mph are not absolute--they are only prima facie evidence of unsafe speed. That is, if you are going 54 in a 25, but can prove in a court of law that there was nothing unsafe about going 54 in a 25, then you get acquitted (This is actually not as hard as you might assume it is).
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# ¿ Sep 7, 2009 00:03 |
Okay correcting myself: the default absolute maximum speed is what I posted before. The default prima facie speed limit is:CVC 22352 posted:(1) Fifteen miles per hour:
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# ¿ Sep 7, 2009 00:07 |
How about putting an island in the middle of the road with a sign on it, or putting in rumble strips a little bit before the crosswalk on either side? That's what europeans would do.
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# ¿ Sep 12, 2009 00:11 |
Commuters do support public transit funding though: They want OTHER people to stop driving so that the roads will be nice and empty for them to drive on!
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# ¿ Sep 15, 2009 09:48 |
Sgs-Cruz posted:Or maybe it wouldn't work because you'd have too high of a burden of proof in showing that it's truly not a new company. Frustrating, anyway.
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# ¿ Sep 18, 2009 23:38 |
Some freeways in Chicago actually have three roadways, with the middle, reversible roadway having periodic ramps to and from the outer ones.
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# ¿ Sep 26, 2009 02:20 |
Cichlidae posted:What method do they use in Chicago to keep traffic from entering in the wrong direction? Bollards?
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# ¿ Sep 26, 2009 02:40 |
Pagan posted:First, in areas like that, do you guys make sure it's easy to "escape"? I noticed that the curbs on the median were sloped, instead of square, so it was easier to drive over. When designing stuff like that, do you anticipate that ppl will gently caress it up, and give them ways out?
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# ¿ Sep 26, 2009 21:32 |
It's illegal to enter ANY intersection if you do not have a clear exit. The ones marked with boxes are just particularly troublesome intersections.
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# ¿ Sep 30, 2009 02:39 |
California still hasn't gotten around to enforcing "Signal before you turn" and "Stop at stop signs", so I dunno how long we are to enforcing those.
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# ¿ Sep 30, 2009 03:36 |
One particularly egregious mistake in my hometown is that, on some intersections, the stop bar is painted beyond an unmarked crosswalk (legally, you have to stop before the crosswalk, even though the stop bar is painted past it). Combine this with hedges that reduce your visibility of the sidewalk and bicyclists who go down the sidewalks at decent speeds and you have accidents waiting to happen.
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# ¿ Sep 30, 2009 18:13 |
smackfu posted:Yeah. It's really the town that should be forcing Walmart to improve the roads, like they do when people want to put in new developments. There's a power imbalance though, because the town really wants that tax revenue, but Walmart doesn't care too much which town it builds in. So the town can't really hardball it.
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# ¿ Oct 2, 2009 17:52 |
Nexis posted:In a CBD (Central Business District) you generally do not have pushbuttons on the signals. In the city we had ~300 signals downtown, all 2 phase with peds. It generally is not worth installing pushbuttons since the signals aren't actuated anyway. Just bring the ped up every time the phase comes in.
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# ¿ Oct 13, 2009 17:06 |
Nexis posted:Nope, pretimed. Peds come up every cycle.
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# ¿ Oct 14, 2009 00:42 |
Cichlidae posted:Yes, that's less than 1,000 feet of 2-lane section on an on-ramp. What's the point?
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# ¿ Oct 24, 2009 21:14 |
What's with this? http://maps.google.com/?ie=UTF8&ll=37.844948,-122.297656&spn=0.001192,0.00284&t=k&z=19 The right lane was gained from the entrance ramp of the previous exit, and instead of being forced to exit, the exit splits off and then the right lane immediately ends. What's the advantage of this over just forcing the right lane to exit? Edit: Also, I wish more states would do what California does and change the dashed lines to indicate that a lane is about to end or split off. It's very helpful! Example here: The "faster" dotted lines indicate where the split is going to be http://maps.google.com/?ie=UTF8&ll=37.73301,-122.412259&spn=0.001194,0.00284&t=k&z=19 Socket Ryanist fucked around with this message at 23:43 on Oct 24, 2009 |
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# ¿ Oct 24, 2009 23:37 |
Cichlidae posted:Wow, that's monumentally complicated. I'd need to spend my career working with those interchanges to have any hope of effectively improving them. Providing sufficient capacity here is the main concern, and meeting all the standards is secondary. The most cost-effective solution, once freeways get this big, is to build bypasses and otherwise reduce the volumes. Increasing capacity at this point is a losing battle; adding more lanes would make some weaving problems, and the right-of-way just isn't there.
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# ¿ Oct 30, 2009 01:08 |
Cichlidae posted:More bypasses, then! Dozens and dozens of concentric rings. Raze the city and pave the whole thing!
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# ¿ Oct 30, 2009 02:15 |
Here's an interesting interchange: http://maps.google.com/?ie=UTF8&ll=40.891683,-72.483845&spn=0.02378,0.038409&t=k&z=15 As you can see, there is an exit on westbound 27 for the road which just diverged from it, which is kind of silly and redundant and I don't know why it even existed in the first place. Additionally, the split to the right used to have an eastbound connection from the upper road, with a traffic light where it crossed westbound 27. People eventually realized this was silly (since there're several other ways to get there and there isn't that much traffic) and just killed the road and turned it into a U-turn ramp.
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# ¿ Oct 30, 2009 17:46 |
How would you fix this clusterfuck of an intersection? I would block off the lower left (santa fe ave) and upper right (oakview ave) legs of the intersection, turning them into cul-de-sacs (with pedestrian and bicycles allowed through) and turn it into a two-way stop with curtis/berkeley park having stop signs and colusa having none.
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# ¿ Nov 5, 2009 06:13 |
Cichlidae posted:Dump the on-street parking, make the island a circle, put in truck aprons if needed, and widen the approaches a bit. It's important to remember that a roundabout will operate more efficiently than an all-way stop in all situations.
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# ¿ Nov 5, 2009 14:56 |
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# ¿ Mar 28, 2024 11:31 |
Cichlidae posted:You could dead-end one of them, as you mentioned before, or just fool around with the geometrics until it works. Better yet, why not transform the southwestern Santa Fe Avenue into one-way eastbound? It would preserve business access, add more on-street parking, and fix the geometric issue. The top road labeled "santa fe ave" is actually colusa, google maps labeled it wrong.
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# ¿ Nov 5, 2009 18:38 |