tag:blogger.com,1999:blog-4063450658421522356.post5802789842961769281..comments2024-03-09T04:13:55.185-06:00Comments on Open PRT specification project: 73> Overwhelmed by an UnderpassDanhttp://www.blogger.com/profile/16303568401426087509noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-4063450658421522356.post-27794213142764944712010-02-26T22:33:23.933-06:002010-02-26T22:33:23.933-06:00Sorry for my absence. I’ve been dealing with the m...Sorry for my absence. I’ve been dealing with the medical emergency stuff that comes with aging parents, and it’s not over yet. <br /><br />Cmfseattle, I was a bit underwhelmed by the advantages of quick elevation changes in the overpass example, although I’m sure there are cases when only a system like I suggest will work. I was surprised to find however, that there are cases where the Anderson designs would work and my system wouldn’t. The example of parallel boarding you site in post 47, though, is one where the steep slope, tight vertical radius capabilities really shine, since they allow the vehicle to drop down for boarding, meaning pedestrians need not cross the tracks.<br /><br />I’m with you in theory, as far as your reasoning for going over the highway. I would love to see an estimate for a cable stayed or suspension PRT bridge. I bet it would be surprisingly cheap. I worry, though, about getting away from the fundamental proposition of dirt-cheap track. What is the trade-off of a bridge vs. more track coverage? <br /><br />Thanks for the help, Alfransen. I guess I should have known. It’s pretty hard to avoid U.S. culture being as close as you are. You know, I grew up just south of Toronto, downstream from Niagara Falls. I could see Brock’s Monument right across the gorge from my bedroom window, and even Toronto, on a clear night. <br /><br />Every time I write a post I wonder how much translation is needed. Do English (as a second language) speakers have any concept of horsepower? (perhaps from an American made motorized product?) And feet… I mean… we all have two of them, even if it’s not very accurate. Does that mean they can envision 50 ft. better than I can envision 15 meters? They taught us metric in school, even “back in the day”, but guys who build stuff (especially motorheads) are late adopters. In the machine shops I use (they mostly do oilfield related parts) everything is measured in thousandths (of an inch).Danhttps://www.blogger.com/profile/16303568401426087509noreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-33806975041944659182010-02-21T05:07:59.602-06:002010-02-21T05:07:59.602-06:00Canadians are mostly comfortable with both metric ...Canadians are mostly comfortable with both metric and imperial. It's a bizarre hybrid really. Height of a person is always in inches, speed of a vehicle is always km/h, temperature is Celsius if its outside, or Fahrenheit in an oven. Construction is done in imperial. It's a real mess. We'd probably be further along in metric uptake if we weren't next to the last bastion of imperial.Andrew Fhttps://www.blogger.com/profile/09182432042622426328noreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-9556290786020396642010-02-21T00:38:54.410-06:002010-02-21T00:38:54.410-06:00i don't like backing-up movements in stations,...i don't like backing-up movements in stations, either. i prefer a parallel design like in post <a href="http://openprtspecs.blogspot.com/2009/08/serial-vs-parallel.html" rel="nofollow">47</a>. mostly, i thought it was interesting that he had numbers for max Gs in sloping segments.<br /><br />i think PRT should go over freeways if possible, so that freeway maintenance doesn't shut PRT down. this scenario is both a challenge and an opportunity: good architecture and a freeway's worth of capacity, without splitting a city.cmfseattlenoreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-40341608451446245812010-02-18T13:59:08.198-06:002010-02-18T13:59:08.198-06:00Dan The Blogger finally gets back to his own blog....Dan The Blogger finally gets back to his own blog...<br /><br />A couple of points. The bottom pic, like the top, has a parallel “feeder” road. To cross that with 16-17 ft. clearance and to then drop beneath the overpass is only an elevation change, which equals the height of the PRT vehicle plus the track. A system like Skyweb Express, if it could only get to the right height, could pass underneath with 8 ft. below it for pedestrians. For a self-leveling hanging system it looks like fences would be needed, but the ease of elevation changes and tight turns would enable a greater percentage of applications where going under would work. Of course there may not be room for both PRT and pedestrians if the PRT hangs down too low to go over them. This is a one pretty compelling reason to try to keep the track/vehicle profile at 8’ or less. For designs like mine, this severely restricts bogie wheel size. Alfransen, do ordinary (non-engineer) Canadians primarily use metric? I confess to thinking in feet and inches, and I try to convert for my posts, but this is just the comments section, and I have a converter in the sidebar, so I’ll be lazy.<br /><br />Going over the highway does indeed mean a 20 ft. rise from a normal elevated track height… and a 200 ft. free-span bridge, in the case of the first example, although it’s a pretty wide highway for most cities. Going over means no slowdown, no bottleneck, though. <br /><br />I was wondering why it seemed like Raymond McDonald was more of a spokesman for Taxi 2000 than someone without a vested interest. I guess the fact that he helped develop Skyweb Express has a little something to do with it. I mean really… Standardize OUT any parallel or back-out boarding? Standardize IN a speed limit and maximum grade? Why standardize having a TV or which way tilt-up seats face? ‘Sounds to me like he is describing the amenities and limitations of Skyweb Express as much as following any logical standardization criteria. I just get a little perturbed when people try to label their own designs as the only possible true PRT and then extend generic logical arguments from there, such as the one where he concludes that only high-capacity PRT can be economically viable. (He didn’t quantify as far I noticed) He includes nothing on hanging systems, which could employ dirt-cheap ground-level open-air stations, nor any sort of tensioned truss, which would have the potential to cut down the number of support structures. Then there is the fact that he presumably assumes this will be done by a single “Swiss-army-knife” company instead of a consortium. None-the-less, I thank you for the interesting read, cmfseattle, and I do not mean to suggest there isn’t a lot of worthwhile stuff in there. There is, (including the other books and articles) and it will make a fine addition to my (very slowly) expanding alphabetical index of links. It’s just a little hard to read while I’m rolling my eyes.Danhttps://www.blogger.com/profile/16303568401426087509noreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-45878991750022876342010-02-16T03:30:43.462-06:002010-02-16T03:30:43.462-06:00you need to change elevation by 20 feet. 10% grade...you need to change elevation by 20 feet. 10% grade = 200 feet, or about where the A is in the upper half of your first image.<br /><br />the bunching on the uphill side is matched by an un-bunching on the other side. at 30mph, the whole thing happens in about 15 seconds.<br /><br />Ray MacDonald proposed some figures for standardization of PRT. you can find the info on page 379 <br />http://books.google.com/books?q=automated+people+movers+2009&btnG=Search+Bookscmfseattlenoreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-22323665554628264762010-02-15T08:38:52.567-06:002010-02-15T08:38:52.567-06:00That last picture seems to indicate that there is ...That last picture seems to indicate that there is nothing under the highway. Seems that a PRT line could just divert slightly to the left or right, and come close to ground level to pass under. You'd need fences/bollards to protect the vehicles as they are close to the ground, but you avoid using up any existing road lanes.<br /><br />A bigger challenge might be such a highway where there is a road that runs underneath, such as the Gardiner Expressway (you've seen it in a lot of movies!) here in Toronto. On the other hand, I believe the Gardiner might be high enough (in places) to allow a PRT line to run between the levels of traffic.Andrew Fhttps://www.blogger.com/profile/09182432042622426328noreply@blogger.com