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excitebike1 posted:Can you describe what conditions would warrant a separate "truck" speed limit? There was a brief discussion of truck limits back on page 45. The conclusion seems to have been that there are certain small benefits (saving money by designing the road for a lower speed) but that reducing the truck speed limit compared to other traffic causes accident rates to skyrocket, so in the balance they're a bad idea. I suspect that whomever's setting the truck limits may also be thinking "they're huge, they can't possibly be safe going at the same speed as my sedan", when really all that happens is that they either pile up trying to obey the speed limit or just go 90 anyway.
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Apr 18, 2011 02:46
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madhatter160 posted:Now for my favorite. There is a rare specimen right down the road from my house! Here we see the first Mini-Roundabout in the US! Is this still in East Lansing? I'd like to try to find it the next time I'm up that way.  Speaking of MSU, generally, the campus is a delight to navigate. However, there's one  The blue arrow is how Wilson Rd. actually proceeds (ignore Google Maps's insistence that there are two Wilsons in that bend; the rightmost one is actually still Fee Rd). The red arrow is what you have to do to get from northbound Fee to westbound Wilson. The green arrow is what you have to do AFTER you get from northbound Fee to westbound Wilson if what you really want to do is make a U-turn on Fee. My kingdom for a roundabout... Also! A quick road-markings question! A major road (US 27, running north-south) near my house has recently been repaved, along with a small stretch of a cross road (Waterfall Rd, running east-west; to the east of 27 is a parking lot). Naturally, they've also been repainted. The intersection is controlled by a standard traffic light. Each direction has two instruments controlling it. (That is, there are two instruments facing east, two instruments facing north, two facing south, and two facing west.) This may be important. The intersection is currently painted like this (I don't have a photograph, and Google Maps isn't up-to-date enough to have captured this):  (There are stop bars that I forgot to render on US 27, and in the parking lot, which was not repaved/repainted, but NOT on Waterfall Rd.) The issue is with Waterfall Rd., on the west (left). From north to south, about 1/3 of the way across is a dashed white line, uneven and obviously made by hand with a spray can as a preliminary mark. 2/3 of the way across is a solid white line, made by one of the large-scale sprayers and obviously an official mark. Between them, the lines divide Waterfall Rd. into three even (and regulation-width) lanes. Here's the question that's caused several near-accidents since the roads were repaved: On the west side of US 27, which direction on Waterfall Rd. has two lanes? e: Since I posted this, they've painted lines on Waterfall. They were painting the stop bars when I got to the intersection! (Also, there's a new double-yellow down the length of Waterfall, where it was unlined before.) The eastbound direction, emptying onto US 27, has two lanes, one left-only and one straight-and-right. The westbound direction, where 27 traffic enters Waterfall Rd., has one lane. This narrows to one lane in both directions about 100 yards beyond the intersection. SneezeOfTheDecade fucked around with this message at 22:44 on Jun 1, 2011 |
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Jun 1, 2011 16:12
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Kalman posted:So: how do you fix this interchange? A purely amateur speculation: You have Onder Park (and maybe some private property? I can't tell) to the east of the freeway, so you can't move the on-ramp any farther east. There's a river and what looks like a bike path to the south of the interchange, so you can't move the off-ramp south unless you want to do some significant bridging. The off-ramp is what's causing the problem for the on-ramp; it needs to have a certain amount of curvature so that the drivers coming off the freeway aren't making hairpin turns while they decelerate from 55 MPH. If the off-ramp weren't there, the on-ramp could be much straighter (and therefore remove the need for an extended merge lane, because vehicles could accelerate on the on-ramp). What I'd do is shave the shoulder coming off the on-ramp, and create an extended merge lane. M14 seems to be wider than usual up until about the sign on the southbound side of the freeway, which looks to my untrained eye to be 15-20 car lengths. By co-opting the shoulder and extending a merge lane out to that point, you'd remove the need for a stop sign and give entering vehicles plenty of space to come to speed. I'm not sure if shaving the shoulder like that is actually legal, but it's a way to improve merging from that on-ramp without any additional construction.
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Jun 9, 2011 18:55
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GWBBQ posted:Cichlidae, is this what your nightmares look like? loving intersections, how do they work? I'm flatly astonished by the free flow of traffic in the directions with flashing reds at several points in the video. The sheer number of people who don't know what a flashing red means... I mean, that's not even "oh, I thought everybody had a flashing red" at that point, that's full-blown "what, it's not the same as a green light?". Also, I kept hearing heavy things shifting in the building you were in and thinking I was hearing car impacts offscreen.
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Jun 20, 2011 02:56
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Qwertyiop25 posted:What in the actual gently caress where they thinking when they designed this. The two red lines are stop signs and the green lines are stop lights. Cross traffic does not stop going east on the northern road. I suspect that the eastbound traffic is supposed to stop, but the stop sign is missing; the west entry to that intersection has a clear stop bar. This seems like a maintenance problem more than a design problem.
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Jun 21, 2011 19:12
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Crackpipe posted:Speed bumps at stop signs - has this ever been tried? It would cause more logistical problems than it solved, I'm afraid, most of them related to perceived right-of-way and having to get over the speed bump from a dead stop.
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Aug 14, 2011 17:21
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Roflex posted:I-83 in southern PA is like that too. It's been like that as long as I can remember and that's at least 15 years. I don't think it's quite 15 years; Pennsylvania was still using sequential numbering when I had to make that drive to and from college in 1997. (I-70 east to I-76 east to I-83 south, then back to get back to college.) I'm pretty sure it was '98 or '99 when they changed over to mile-based numbering, because it was while I was in college the first time, and I took an extended leave in the spring of 2000. I'm reasonably certain that those get left up simply because it's less expensive to do so. There's no practical reason to take them down, and if the state wants to remove them they have to pay workers to go out and do it.
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Aug 18, 2011 15:37
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grover posted:We've had some drama in the VA Beach area between cars and bicyclists, to the point of some road-raging imbecile going around, tossing thumbtacks into various intersections to deter bicyclists. "They're not thumbtacks. They're drywall nails." Seriously, though: I wouldn't bicycle on that road or any road like it. That's a recipe for disaster, and honestly I would be a little worried for the mental health of any cyclist who insisted on occupying right-of-way on that road. I'm not sure of the relative costs, but less expensive than adding bike lanes might be adding a bike trail that follows that road, thereby removing cyclists from the equation entirely (and being actually, from a public-opinion standpoint, more bike-friendly than bike lanes).
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Aug 21, 2011 01:06
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Millstone posted:Can anyone tell me why the New Jersey Turnpike and I-295 seem to parallel for several miles? Help me out here, I don't deal with many toll roads. It just seems highly counter-intuitive to run two freeways right next to each other. The New Jersey Turnpike is intended to be part of a non-stop high-speed freeway from Washington DC to New York City, and as such has limited local access. I-295 has more local exits. As for why the roads are built next to each other rather than being concurrent, I suspect that the "non-stop high-speed freeway" bit plays a part in that; adding local exits to the turnpike would have reduced traffic flow during construction and would have added congestion after the exits were constructed.
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Sep 20, 2011 13:46
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Mandalay posted:Remind me how dangerous it is to buy a motorcycle please Buying a motorcycle isn't dangerous in and of itself, but riding one? Yeah, that's pretty dangerous. ...oh, wait, were you trolling? I'm sorry.
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Oct 27, 2011 18:07
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Gothmog1065 posted:Can you explain what this retarded poo poo accomplishes? That's a bog-standard Michigan left, which is trivially more complex in terms of traffic geometry but carries MASSIVE improvement in accident rates and traffic congestion.
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Nov 16, 2011 08:33
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Samurai Sanders posted:Hm, lemme rephrase a bit: Who decided that the solid walk light was going to be only 4-7 seconds long, and why? It's not a practical issue or anything, I'm just curious, I have been for years, ever since they installed those countdown things and it showed me just how long that flashing red period was. It's clear that thought was put into how long the flashing down't walk period was, so I'm wondering what the thought was behind the length of the walk sign. I think it's less a matter of deciding that the walk light's only going to be 4-7 seconds long and more a matter of actual traffic phases. Let's say that a road is 4 lanes wide, with no turn or acceleration lanes, and that the traffic light is red for 25 seconds. The minimum width of a through lane is 10 feet, and lane markings are 6" wide (IIRC). Add a 3' shoulder on each side, and the total width of the road is (3'+6"+10'+6"+10'+18"+10'+6"+10'+6"+3') = (3'*2+10'*4+0.5'*4+1.5') = 49.5' from sidewalk to sidewalk. (We'll ignore the time it takes to step off of and onto the curb.) Since the designers are assuming 3.5 feet per second walking speed, the time to cross the street is 14.14 seconds, which they have to round up to 15. That's the absolute minimum that the flashing Don't Walk hand can be up (because they have to allow for people who entered the crosswalk at the last possible moment during the Walk signal). There's a 4-second grace period after the flashing Don't Walk turns to the solid Don't Walk, and the solid Don't Walk doesn't turn into the Walk signal until a second into the phase. So the walk signals look like this: 25-second cycle phase starts Don't Walk (S): 1 second Walk: 5 seconds Don't Walk (F): 15 seconds Don't Walk (S): 4 seconds Phase ends TLDR: The length of the Walk signal isn't consciously determined; it's what's left over in the phase after the Don't Walk times are taken out. If the phase were extended to 30 seconds, that Walk signal could go up to 10 seconds, and so on. It's not unheard of, on signaled intersections between very busy streets and very not-busy streets, to have stop phases on the cross street that last up to a minute, which would give you a 40-second Walk signal given the conditions above. SneezeOfTheDecade fucked around with this message at 03:52 on Dec 7, 2011 |
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Dec 7, 2011 03:45
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nielsm posted:alt.games.microprose.transport-tycoon Apropos of absolutely nothing, I grew up just north of Hunt Valley, MD, where MicroProse was headquartered. In the late 80s my Cub Scout troop took a trip to MicroProse headquarters - it was right before the release of F-15 Strike Eagle II - and while we were there, we ran into a fellow walking down the hall. The guy giving the tour introduced us: "This is Sid; he's one of the originals, involved in a lot of the games around here." Sid laughed, said, "Yeah, you could say that," and shook all of our hands, and then walked off. I hadn't thought of that moment until I saw the name MicroProse in your post and went to Wikipedia it to find out what they were up to these days - and discovered that when I was nine or ten years old I must have shaken hands with Sid Meier.
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Dec 18, 2011 00:41
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Tots posted:I'm road tripping right now and am coming up on a 2 to 1 lane merge due to.constriction. Driver just said that traffic will move faster if two lanes are utilized until the merge point. I say the sooner everyone merges the faster the traffic will move. Who's right? As far as my understanding goes: * For an individual car, he's right; * For traffic overall, you're right. That is: traffic overall will move faster if everyone merges as soon as possible, since most of the movement delay is due to letting people near the merge point join the main traffic flow. However, an individual car can leapfrog the line by staying in the closing lane until the last possible moment. Doing this will almost always put you in a position in traffic ahead of where you would have been had you merged early, and since you will have traversed the intervening distance more quickly, you will ultimately move more quickly if you drive as far as you can in the closing lane before moving. It's sort of a tragedy of the anticommons: each driver's right and desire to travel individually as quickly as possible slows down traffic on the whole. And sadly, most drivers aren't thinking about traffic as a whole when they're driving; they're thinking about how to get from point A to point B as quickly as possible. Dominus Vobiscum posted:The driver is right. Zipper merging is more efficient. If there's no congestion, it doesn't matter. However, if everyone is merging before the merge point and there is congestion, then you run into the problem of wasted space on one lane, people running up to the merge point and then getting stuck or trying to edge into the lineup, and a greater difference in speeds between the two lanes. The problem here is that zipper merging is a Platonic ideal. In actual practice, you run into the same problem that I mentioned above - the individual driver wants to get from A to B as quickly as possible, which means that cars in the continuous lane are reluctant to let cars in the merging lane merge. Zipper merging works wonderfully if everybody is on board - but in practice, almost nobody ever actually is. SneezeOfTheDecade fucked around with this message at 17:07 on Dec 27, 2011 |
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Dec 27, 2011 17:03
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KozmoNaut posted:In proper zipper merging, there isn't one continuous lane. There are two continuous lanes. You forgot your "  ".KozmoNaut posted:Zipper merging at the merge point has been proven time and time again to be the fastest way to move traffic when two lanes compress into one. quote:Zipper merging works wonderfully if everybody is on board - but in practice, almost nobody ever actually is. You're absolutely correct that in tests and simulation, zipper merging wins every time. In the wild, you'd be lucky to find 30% of drivers to whom "zipper merging" may as well be a Martian concept. You get drivers who refuse to let mergers in, mergers who try to slip in with the (unrelated) merger in front of them, convoys that need to merge together, people who just let everybody merge in front of them in an attempt to "clear" the merging lane... Until most drivers know what a zipper merge is, how to execute it, and that it's effective, I maintain that it simply isn't as efficient in practice as it is in simulation.
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Dec 27, 2011 17:31
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Cichlidae posted:we could brute-force it by dropping concrete barriers in front of every driveway. I'm pretty sure this would result in only lousy drivers being on the road.
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Jan 27, 2012 07:26
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