tag:blogger.com,1999:blog-4063450658421522356.post6794468740161762313..comments2024-03-09T04:13:55.185-06:00Comments on Open PRT specification project: 49> In Search of Gridlock and OpportunityDanhttp://www.blogger.com/profile/16303568401426087509noreply@blogger.comBlogger18125tag:blogger.com,1999:blog-4063450658421522356.post-61135690822552909122016-07-20T05:05:01.592-05:002016-07-20T05:05:01.592-05:00LibreOffice will run on MS and read Excel sheets.
...LibreOffice will run on MS and read Excel sheets.<br />But on topic, I think you have to sort out the stops further. On a two-way system, passengers arrive at a stop that is attached to one direction. How do they go in the other direction?Anonymoushttps://www.blogger.com/profile/05553628099663369316noreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-85676795648426043612009-09-15T15:51:32.113-05:002009-09-15T15:51:32.113-05:00Dan The Blogger Returns-
Thanks for the posts, Jo...Dan The Blogger Returns-<br /><br />Thanks for the posts, John. I don’t currently have Excel,…(maybe that’s a blessing…)<br />I have been meaning to download “Excel Viewer” from the MS site to see if it would work for your simulation but haven’t found the time. I’m afraid that this blog is something that I have to fit in weekends and after-hours. <br /><br />You envision a much bigger system than I do, and, as you say, there may be some cultural bias for this. Anything even remotely resembling a train would run into huge opposition in most US cities, and would run squarely up against the forces of traditional light rail, which no initial PRT system here is likely to survive. I think as light as possible is the key. In the U.S., we have the experience of the Raytheon model of PRT, which was shown to be too massive for the tastes of the cities they approached. I will readily admit though, that getting the economies that you mention with a smaller lighter system will be a challenge. <br /><br />Hi cmf.. That link only worked once for me and now gives a 404 message. It is a great 2-part summery and history of PRT, and can be read by searching for “podcars” in the Examiner’s search box. There is little telling what others will experience, however, because the site tailors itself to the city of the reader. I must say, though there is some really great old grainy footage of the Aerospace Corp’s early PRT test model doing its thing. I’m going to put that in a “best links” post one of these days.Danhttps://www.blogger.com/profile/16303568401426087509noreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-11285044242074134642009-09-12T15:46:34.809-05:002009-09-12T15:46:34.809-05:00There will never be enough guideway in a successfu...There will never be enough guideway in a successful PRT network. There will be strong opposition to every km of new track on grounds of cost and planning.<br /><br />The answer to the cost is simple: get as much revenue out of each bit of the guideway as possible. This can be done by:<br /><br />- Coupling vehicles<br />- Reducing headways<br />- Higher speeds<br />- Mixed traffic, freight when passenger demand is low and<br />- Mass transit vehicles as well<br /><br />I suspect the planning issues are less of a problem in the USA than in Europe. Streets are narrower and more chaotic in layout and the citizens are much more protective towards scenic aspects of historic buildings and street scenes.<br /><br />A PRT system will be more acceptable if it has:<br /><br />- Low bulkyness<br />- Compact stations<br />- Stations at grade<br />- Can go underground<br /><br />The ideal network would have many parallel routes to a particular destination but I think that in real systems there will be regions of guideway linked by a single route. (eg. either side of a river) It will be the capacity of a single guideway that matters in this situation.John Greenwoodnoreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-57142799321322743192009-09-12T02:16:53.643-05:002009-09-12T02:16:53.643-05:00Capacity in a PRT system is mostly a function of t...<a href="http://www.examiner.com/x-18921-Seattle-Transportation-Examiner~y2009m9d8-PODCARS--A-Personal-Rapid-Transit-primer" rel="nofollow"><i>Capacity in a PRT system is mostly a function of the number of pods, and short headways between them. Congestion is avoided by having a set number of pods, in contrast to the continual increase in new automobiles being put on the roads. Capacity is the number of trips each pod makes, times the number of seats per pod, times the number of pods in the system. Just as an example, in a fleet of 1,000 four-seat pods each making five trips per hour, the capacity is 20,000 passengers per hour. Therefore on-demand service is the chief difference between PRT and light rail -- light rail is good at moving large groups in trains many minutes apart, along corridors; PRT serves the same number in smaller groups, with pods sometimes separated only by seconds, around a grid-like network.</i></a><br /><br />i figured out that our 3-mile example system should be able to handle well over 100K vehicles/hr ((15840ft/132ft/sec)*20new trips/min)*60mins = 144K trips/hr.<br /><br />however, once again, that's only if all parts of the network are being utilized to an equal degree (balanced load). i'm suggesting coupling in order to increase the maximum psgrs/hr along the most congested segment(s), using standard-issue vehicle$.cmfseattlenoreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-69990879275916520032009-09-09T06:49:37.639-05:002009-09-09T06:49:37.639-05:00cmfseattle, Thanks for pointing out the muddled ax...cmfseattle, Thanks for pointing out the muddled axes labels, now corrected.<br /><br />Coupling individual vehicles will increase capacity particularly if the speed is greater. This would not affect the number of berths for a given passenger flow but would mean that station capacities could be even larger.<br /><br />If mass transit traffic is carried on the same guideway as PRT, it will have to negotiate the same tightness bends. <br /><br />Here is my idea for such a <a href="http://distart041.ing.unibo.it/~john/Cabin_in_PAT/images/Ten_Cabins/Train.gif" rel="nofollow">vehicle</a>.<br /><br />Which would be articulated as in this <a href="http://distart041.ing.unibo.it/~john/Cabin_in_PAT/images/Animations/BendA.gif" rel="nofollow">Animation</a>.<br /><br />At higher speeds this has <a href="http://distart041.ing.unibo.it/~john/Cabin_in_PAT/Ten_cabin_carrier.html" rel="nofollow">attractions</a> for low drag, low energy consumption and passenger numbers similar to a bus.John Greenwoodnoreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-43741950329056655152009-09-08T23:18:00.323-05:002009-09-08T23:18:00.323-05:00John, thanks, although the chart at the bottom of ...John, thanks, although the chart at the bottom of the "capacity of PAT guideways" (PATcapacity.html) is at first a bit confusing; seems like the left column should be 10, 20, etc. Km/H, and the bottom row label vehicles/minute?<br /><br />anyway, i think that uncoupling at the arrival end of a station (to facilitate a parallel config), and coupling 2 or more vehicles with the same destination at the departure end, would be feasible. automatic couplers aren't new and allow emergency pushing (as in the taxi2000 design).cmfseattlenoreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-65889752488676459072009-09-08T14:12:36.588-05:002009-09-08T14:12:36.588-05:00Following my contribution above, here are the link...Following my contribution above, here are the links as html:<br /><br /><a href="http://distart041.ing.unibo.it/~john/Berths/images/Downloads/Sequental.xls" rel="nofollow">Sequential Berthing spreadsheet model</a><br /><br /><a href="http://distart041.ing.unibo.it/~john/Berths/images/Downloads/Iterate_macros.xls" rel="nofollow">Iterate macros</a><br /><br /><a href="http://distart041.ing.unibo.it/~john/Berths/Models.html" rel="nofollow">Page with links to other models and discussion</a><br /><br />Also relevant is a <a href="http://distart041.ing.unibo.it/~john/Cabin_in_PAT/PATcapacity.html" rel="nofollow">chart</a> I made to try to put PRT passenger volumes in a wider contex.John Greenwoodnoreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-25569112504324647192009-09-08T06:20:17.670-05:002009-09-08T06:20:17.670-05:00Hi
Can I point your readers to some rather simpli...Hi<br /><br />Can I point your readers to some rather simplistic but instructive simulations of PRT stations I did recently.<br /><br />Download the EXCEL spreadsheet:<br /><br />http://distart041.ing.unibo.it/~john/Berths/images/Downloads/Sequental.xls<br /><br />You should open a spreadsheet with some cells coloured green and red. Press F9 to iterate and they will move up.<br /><br />Now load: http://distart041.ing.unibo.it/~john/Berths/images/Downloads/Iterate_macros.xls<br /><br />This contains a set of macros which repeat the interation a number of times as described in cells S3:T7 so, for example, if you press ctrl-U it will do a cycle of 3 iterations which is one time unit.<br /><br />If this dosn't work for you, PLEASE let me know at John@john-Greenwood.co.uk.<br /><br />There are models for other types of berthing and discussion at: http://distart041.ing.unibo.it/~john/Berths/Models.html<br /><br />In all these models you can change the configuration, for example in the Sequential model, changing the logic state of cell L52 to FALSE will disable the berth on that line<br /><br />The passengers have a randomly variable boarding time with a Weibull distribution. Parameters for four different passenger mixes are available on all the sheets.<br /><br />So for example, to change the mix from "typical" to one with fit people only, copy the cells N21:N23 (coloured blue) to H21<br /><br />I would not claim that the results are particularly accurate but good for comparative purposes. In particular it shows how throughput tends to be limited by congestion of vehicles.John Greenwoodhttps://www.blogger.com/profile/05316545448793503259noreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-65354522253775401232009-09-07T23:39:40.572-05:002009-09-07T23:39:40.572-05:00Dan, at 30mph line speed, 188ft = 4.28sec headways...Dan, at 30mph line speed, 188ft = 4.28sec headways and at 4psgrs/vehicle, you'll take an hour to move 4,500psgrs. coupling doubles that number, so you could move 20% of a WWE event (they hold the attendance record of 50K at seattle's baseball stadium). then again, that would be double the national average transit ridership.<br /><br />however, if you need ~$13K a day to turn a profit, you're barely squeaking by without the capability to couple at least some of the vehicles (especially with so few stations).<br /><br />i think your comments about remaining grounded in reality are spot on. financing <b>does</b> affect PRT design.cmfseattlenoreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-17997911438895084312009-09-07T15:43:01.641-05:002009-09-07T15:43:01.641-05:00Oops! 4096 characters max per comment.
Dan continu...Oops! 4096 characters max per comment.<br />Dan continues <br />Hi Akauppi, <br />The exact method of payment would seem irrelevant at this stage. For the purposes of analyzing cash flow in a hypothetical mini system it would seem that the more straightforward way would be best. I guess that most systems envision a payment card of some type, probably including ID involved to keep down vandalism. If a card is swiped, what’s the difference? Isn’t it all the same except in the computer that is doing the accounting? I suppose later on a season pass or express check-in might save some time, though. <br /><br />I’m really not sure who the “customer” is in your example. The city? In the U.S. I think there is a pretty complex relationship between the city, the state, the federal government, and the transit authority. I do not pretend to understand even half of it. Revenues include things like city services, property taxes, city-sponsored bonds, federal and state grants. Sometimes politicians “bring home the pork” as it is called, directly to their local constituencies in the form of a government grant. However it’s done, PRT should be revenue positive, especially if it is to start out as a public private partnership, such as an airport or campus that extends onto city property. I think it’s one step at a time, unless, of course, this would have a bearing on the physical designs. I guess my concern is that some payment schemes my hide, to some extent, the financial realities, which might make it unclear whether a project is a success or failure, and by how much.Danhttps://www.blogger.com/profile/16303568401426087509noreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-92146297788513878752009-09-07T15:31:08.530-05:002009-09-07T15:31:08.530-05:00Dan The Blogger responds[
First of all, it is my ...Dan The Blogger responds[<br /><br />First of all, it is my style to break complex issues into small, digestible pieces. It is how I learn, design, and teach. This blog is ideally suited to this methodical approach. I hope to see a full set of design specifications come out of this effort one day, but that will take the talents of a much bigger audience than I have so far. In the meantime, I am exploring the issues one at a time. There are lots of myths, assertions, and assumptions that fly around the topic of PRT and any good system needs to grounded in reality. <br /><br />The underlying inquiry here is two fold; what is the smallest, least expensive PRT configuration that makes economic sense, and secondly, can PRT stations keep up? As per the first question, I would like to note that this is important from a PR point of view. It is psychologically easy to take a workable concept and scale it up. Not so easy in reverse. As for the second question, this exercise indicates that, for one thing, the advocates of “track on the bottom” have a real design challenge in a high volume station, because of the “crossing the tracks” problem. (Andreasson, in the above link envisions a cumbersome scheme up to 65 PRTs in a row to handle transfers from a train) <br /><br />Anonymous, Thanks for the perspective view. I wish there wasn’t often a commuter dead zone between airports and CBDs. In many cities the airport is way out of town. It would be nice to get part way to some long-term parking, though. Of course for that matter it would be nice to park the car and PRT into town. <br /><br />Cmfseattle brought up the “linking cars together” discussion. Sorry, that’s a post I haven’t written yet, and won’t get into here. (Although you folks can, if you choose,)<br />I would like to point out a simple fact, however, than in regard to the example above, the following may be stated. Total track=3 mils=15,840 ft. Number of vehicles in the system = 126. (This is in the stations and storage as well as on route) 15,840 divided by 126 equals the minimum distributed spacing. (on center) That number is 126 ft. This assumes ALL vehicles are on the track and none are in a station. If a third of the vehicles are boarding, that number is 188ft. That kind of spacing would hardly seem to cry out for coupling. As I was saying back a few posts ago, for “mini” system the problem isn’t track, it’s the stations. I’ll try to post on this subject soon. <br /><br />Ollie, This really isn’t a good forum to discuss numeric details and detailed performance claims, unless they can be very easily and concisely verified. The whole PRT industry has a credibility problem which is baked in to its fabric, because there are so few impartial observers to audit claims, and because so many projections must be premised on assumptions. That is why vendors generally take such pains to authenticate their data and stick to a rigorously scientific approach. I do not believe nor disbelieve. I am an optimistic skeptic, and for the purpose set forth in this blog, I think that is how I should be. I try to make a few good points and get people thinking each week, while I build readership. In the broadest context, this post was about how station capability and system scale might effect vehicle and track design. It is also an exploration of the boundaries of system design. I will generally try not to endorse or reject anything in this blog until it is time to commit to a design choice.Danhttps://www.blogger.com/profile/16303568401426087509noreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-17672221841185060512009-09-07T02:05:51.020-05:002009-09-07T02:05:51.020-05:00I think you're on the wrong foot in pricing in...I think you're on the wrong foot in pricing individual trips on PRT usage. That's at least not how public traffic works here (Finland). We're trying to get away from paying for individual trips, and for people to use season cards instead. It's way more simple for everyone.<br /><br />This offers another business model: selling the PRT system as a transport solution, guaranteeing certain bandwidth between stations and maintaining the service at any time.<br /><br />In this case, the customer is responsible of charging the end users. It also means, it is the customer's concern to get much usage on the system. The PRT operator will get fixed price agreed up-front, not based on the number of passangers actually using the system. This takes a huge risk away from the PRT operator's shoulders, and more precisely focuses the roles of the players.<br /><br />Whether there is any way such a business plan would work among the Americans, I don't know. But it would work in many places, and it especially makes sense where other traffic modes (buses, local trains) are being paid for with the same travel cards (s.a. in Helsinki region). We are looking for efficiency of transport (not multiple parallel services covering the same need) and still maintaining competition within that transport network. Maybe Helsinki and HKL is a world first in making this everyday reality already now.<br /><br />(What I mean is that i.e. introduction of PRT in a certain area could be used to completely remove local buses from there. In a non-managed environment, the buses would remain and try to compete with PRT. In the transition there would be worst of both worlds - PRT track pillars and buses running half-empty. Not ideal. If both modes are part of the same overall traffic planning, this can be avoided. Also Heathrow has the same case, ULTra replacing airport bus lines.)Asko K.https://www.blogger.com/profile/17128056786952824895noreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-56293583637480732492009-09-06T17:52:10.989-05:002009-09-06T17:52:10.989-05:00my thoughts of late:
what are the top 3 things you...my thoughts of late:<br />what are the top 3 things you'd change about transportation if you could?<br /><br />1) cost -- both in money and time. there's insurance, maintenance and fuel. currently, 2nd biggest purchase, for most.<br /><br />2) convenience -- cars can serve more functions, but need parking (add to cost, above). unless you live rural, there's a limit to how many can fit during rush hours. transit can often take twice as long and, like bikes/scooter/motorcycles, can mean dealing with the weather.<br /><br />3) culture -- from rude drivers/passengers to international politics (social justice, energy, materials, etc.), it's better to lead by example.<br /><br />no one (almost) suggests curbing population as a solution to congestion, right? so, the goal is to move more people and their stuff from home to work, school, play, shopping, recreation and back, in the most efficient manner possible.<br /><br />maybe that means starting with fenced rights-of-way and low speeds. once you prove that it's safe and cost-effective, you can continue toward intercity maglev.cmfseattlenoreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-48341354150802693332009-09-06T17:08:22.844-05:002009-09-06T17:08:22.844-05:00"But it might be possible for vehicles to be ..."<i>But it might be possible for vehicles to be able to get arbitrarily close to each other and even touch if a shock-absorbing bumper system is introduced--say, one on each end extending a few feet in front of the rest of the vehicle.</i>"<br /><br />please read up on the french Aramis system. i'm not suggesting vehicles couple and uncouple at speed. i'm suggesting they be coupled just before rush hours in order to increase the main line capacity without headways below 3 seconds.<br /><br /><a href="http://www.advancedtransit.net/atrawiki/index.php?title=Aramis" rel="nofollow">http://www.advancedtransit.net/atrawiki/index.php?title=Aramis</a><br /><br /><a href="http://faculty.washington.edu/jbs/itrans/pulse.htm" rel="nofollow">http://faculty.washington.edu/jbs/itrans/pulse.htm</a><br /><br />once again, the problem is: how to pay for a starter PRT system? you'd have to charge passengers $3/trip if you can only handle 5,000/day. and 1,250/hour is near the upper limit at 3secs headway, 1.2psgrs/vehicle average.<br /><br />ULTra are keeping costs down by limiting the amount of elevated segments and keeping it simple.cmfseattlenoreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-31330231728435596922009-09-06T15:25:35.489-05:002009-09-06T15:25:35.489-05:00Dan,
It all depends if someone believes that PRT ...Dan,<br /><br />It all depends if someone believes that PRT can be made to have a subsecond density vehicles separation. If not, then it ends the discussion, because then, as the PRT foes say, it will never be able to have high capacity, therefore profitability.<br /><br />But I know, that my 1st 7 mile MISTER system (seed configuration, costing $50 mil) WILL be able to deliver over 5,000 ppdph, with some 35,000 passenger-miles per hour. This is more than any LRT or bus system of the same length and only 50% less than a subway (which would cost 30 times more). Of course, with the growth of the PRT system, it becomes better and more profitable.<br /><br />And I also know, that a 7 mile LRT systems are designed to carry 50,000 passengers per day, even in such countries like Poland. With such parameters, and an average ticket price of $1,50 for an average 3 mile trip, such a system would entirely pay for itself in e.g. San Jose (or any other US city) witin 1-2 years. <br /><br />But it seems that we can discuss it till we are blue, because nobody, even you, want to look at these numbers as something realistic. This is why you are searching for esoteric schemas of some large station, multi-level stops, remote and low cost stops etc. There is no need for such ideas, because simple, small yet numerous stops in densly built up city areas or around sports stadiums are more than feasible and more than enough. <br /><br />Looks like you didn't read my Capability Analysis (http://www.mist-er.com/mister-description/capability-anaysis.html) or if you did, then you didn't tell me if and wrong you've found with it. <br /><br />Anyway, once again all the best to your continued search for the best PRT system but it seems that I have nothing more to offer, other than what I did so far.<br /><br />Cheers to all of you - OllieOllie Mikoszahttps://www.blogger.com/profile/15734322700555351748noreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-84208682744083092212009-09-06T11:03:05.219-05:002009-09-06T11:03:05.219-05:00I don't think physical coupling is necessary, ...I don't think physical coupling is necessary, and it introduces some problems. But it might be possible for vehicles to be able to get arbitrarily close to each other and even touch if a shock-absorbing bumper system is introduced--say, one on each end extending a few feet in front of the rest of the vehicle. This, along with some creative fairing, can allow vehicles to draft each other while still maintaining a degree of safety should a sudden deceleration be necessary. That said, the high capacity that vehicle coupling or drafting can provide is not likely to be necessary in the initial systems. If the Seattle monorail's 5,000 passengers all rode within, say, four hours of the day, that would still only be 1,250 passengers an hour, well within even the most rudimentary PRT system's potential capacity range. And of course the fact that you can build multiple PRT lines for the cost of one conventional transit line means that single line capacity isn't really that great a limiting factor.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-42190876419473932772009-09-06T02:17:35.010-05:002009-09-06T02:17:35.010-05:00you'd have to make the guideways stronger, but...you'd have to make the guideways stronger, but "coupling" vehicles might make sense.<br /><br /><a href="http://faculty.washington.edu/jbs/itrans/ingmar%20-%20extending-prt-capacity.doc" rel="nofollow">Extending PRT Capabilities, by Ingmar Andreasson</a><br /><br />the seattle monorail moves an average of 5,000psgrs/day between 2 food courts, and turns a profit. the capital costs were paid back by being able to handle 5,400pphpd during the 1962 world's fair.<br /><br />Prof. Jerry Schneider's <a href="" rel="nofollow">Bellevue Downtown PRT Planning Study</a> used a $16M/mile figure and a limit of 12 guideway miles.cmfseattlenoreply@blogger.comtag:blogger.com,1999:blog-4063450658421522356.post-27102042428950013202009-09-05T23:07:07.556-05:002009-09-05T23:07:07.556-05:00Focus on connecting airports to CBDs and existing ...Focus on connecting airports to CBDs and existing transit hubs. People pay lots of money for airport taxis. Airports also have a much steadier flow of passengers than stadiums, since planes arrive and depart 24/7, and air travelers are highly transit-dependent.<br /><br />The AirTrain connecting JFK terminals to the LIRR and NYC subway system cost $230 million a mile. It carries 15,000 paying passengers a day at $5/passenger for a 1.5-3 mile ride--or <b>$1.70-$3.30 per passenger mile</b>. Even at that steep fare it only recoups less than 2% of its construction cost each year. <a href="http://en.wikipedia.org/wiki/File:Air_Train_JFK_Van_Wyck_jeh.jpg" rel="nofollow">And just look at it</a>. When people complain about PRT cost, capacity and intrusiveness, show them this.Anonymousnoreply@blogger.com