Inflexible Inventory

Post by Steven Dale

Ultimately, the problem with public transit is one of economics. Our current transit systems have no ability to adjust the supply of their inventory levels (seats) to match a given demand (ridership) at a given time of day. Its inventory is completely inflexible:

  • Rush Hour: Too much demand, not enough supply.
  • Late Night: Some demand, no supply whatsoever (typically).
  • All other times: Far too much supply, not enough demand.

The problem is compounded by the unidirectional nature of the demand versus the bidirectional nature of the supply. During the morning commute, riders need to go from Point A to Point B. Point A being home and Point B being some form of central business district, whether that be a financial core or a suburban office park.

But for a standard transit technology to satisfy that need it must move from Point A to Point B and then back to Point A in order to service more riders. Trouble is, that means vehicles and drivers spend fully half their time traversing a route with near empty vehicles which are not generating revenue only additional costs. Too much demand in one direction, too much supply in the other.

So long as transit vehicles are expensive and drivers costly and necessary, these problems won’t disappear.

Solution: Drive down the cost of returning vehicles to origin so that it’s marginal rather than almost half. Far easier said than done.

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  1. Particularly not easy when the cost of the returning vehicle includes a reasonable share of depreciation and maintenance, including for both the vehicle and whatever infrastructure it is using. I'm actually wondering if this proposed "solution" is even possible, at least defined in those terms--will carrying passengers ever make that much of a difference to transit systems, such that the fairly-allocated cost of the returning vehicles is really much less than half? The alternative conclusion is just that for this reason you want everything relevant to be as inexpensive to build and operate as possible. Not a terribly clever or interesting concept, but it may be the practical upshot.
  2. Just brainstorming a bit: Question #1: Why aren't passengers a greater percentage of the total weight of buses, trains, and so forth? Answer #1: Because in addition to just propulsion, you need a lot of extra heavy stuff to keep your passengers safe and comfortable while moving them around at high speeds. Question #2: To solve the return problem, why don't you just buy more vehicles, using them one way in the morning, and the other way in the evening? Answer #2: For one thing, to the extent your return costs are fixed per vehicle, that doesn't help. For another, storing a bunch of extra vehicles, particularly in a crowded CBD during the day, would be very costly. Brainstorm: OK, so what if you could detach a lot of that extra heavy stuff you need to keep passengers safe and comfortable from the (potentially expensive) propulsion system. And what if that extra heavy stuff was easier to store in smaller volumes. I'm imagining something like only the parts of buses above the floor, designed to stack like cups (maybe including with folding seats). Call these passenger shells. And finally, what if you could just return the propulsion part to pick up another shell. If you did that, you could just buy more shells, not entire vehicles (including duplicative and expensive propulsion systems). And maybe the storage problem for just shells wouldn't be so bad. In a system like that, maybe you could in fact widen the cost gap between the primary trips and the return trips. So what about something like gondolas? The good news is we already know you can have shells which detach from the propulsion system. But the fixed cost savings are not so high, because the propulsion system is pretty cheap (as spread out among the vehicles). And the big question--could you figure out a way to make detachable gondola shells compactly storable, such that whatever savings you got in operations on the return half wasn't swamped by storage costs? I'm thinking that doesn't sound so promising for gondolas--it may well be cheaper in most cases to circulate them empty rather than try to store them in your CBD. But I'm kinda fond of my stackable bus shell idea--I wonder if I can find someone in China to run with it.
  3. Oh, and you have to do something about the drivers. Driverless detachable-shell vehicles would be ideal, but I'm thinking a roll cage and windscreen (and decent insurance) might be sufficient.
  4. Actually the best way is to tackle the problem on its roots: City planning. It is possible to build cities which are somewhat balanced so there is traffic in both directions, or better yet it is not needed to commute at all. Just a note traffic for going to work or school accounts in western cities only for the half of passenger/km the rest is leisure or shopping trips. So the assumption in the morning everybody goes to the CBD and on the evening they go back is wrong. Some people live and work in the outskirts and go to town on the evening for shopping, have dinner at a restaurant or to watch a movie.
  5. Matthias, I agree totally with your assertion that the way to solve this problem is to build cities where traffic goes in both directions. I don't, however, agree with your other assertion that the assumption I make is wrong. Let me explain: Around 50% of transit riders use it to get to work/school. True. The problem is those 50% are crammed into only 4 hours (two 2 hour rush hours) out of a 24 hour day. That means 50% of ridership occurs during 1/6 of the day. That means during rush hour things are overcapacity and during the other 5/6 of the day, systems are well under capacity. That, I feel, is the fundamental problem.
  6. Brian, I have no idea how to "solve" this problem. I think the fact that it hasn't been solved after 100 years says something. I do, however, believe this is the fundamental problem transit faces.
  7. I'm digging on the stackable bus concept myself. Problem is drivers. Can we stack and store them too?
  8. "Solve" may indeed be too strong. But I think it can be--and indeed implicitly has been--addressed simply with exploiting any available and relevant cost-saving techniques. That won't necessarily address the relative costs, but it will drive down the return costs. I'm thinking of the drivers as part of the propulsion system that is cycled back (maybe "propulsion and guidance" system would be better). Assuming they are paid hourly, it would indeed be better if they could be "deactivated" for return trips, and maybe "stored" doing other work in the CBD. But all that may be impractical--probably better just to go entirely driverless if possible, or accept the hit on overall costs if not possible.
  9. I really liked what Brian was saying and agree a lot. “I’m thinking that doesn’t sound so promising for gondolas–it may well be cheaper in most cases to circulate them empty rather than try to store them in your CBD.” Very right! 1. But there is one big disadvantage of those gondolas. Let’s talk about the photos I see on flickr or else of the medellin cable cars. Nothing, really, nothing hurts me more than seeing empty vehicles moving around. May those be buses or gondolas. But urban cable cars are visible to everybody due to their height. So this fact gives you bad taste about transportation and energy, although during rush hour all of them (metro, street cars and buses) are overcrowded and more capacity would be even better. The funny thing is that everybody seems to be okay with the fact that almost every car runs at 1/5 of capacity. Maybe within the next 100 years the solution will be found. 2. So, the solution for road transportation right now would probably be Car2Go or better: Bus2Go ;) Ok, Car2Go already exists, but think about it in a bigger scale. Or cars should have a sign on their roofs like taxis have which says: OPEN (for others to join the ride). Which would be the same like the next point I'm going to mention, but much more spontanious. 3. There is one other interesting phenomena you should know about (and maybe Steven could take a deeper look into it – i think an own topic would be useful: similar ideology to http://www.couchsurfing.org/ more and more people since about 6 years are using http://www.mitfahrgelegenheit.de in Germany ( http://www.rideshare.co.uk/ is the british equivalent ). And I have to tell you it works really good. Funny thing about it is some of you certainly remember the old way of hitchhiking with a handwritten sign next to the road which has the name of the desired destination on it. Since about the time ridesharing was introduced to our society I hardly saw those hitchhikers.
  10. 4. Next scenario: cars should be more optimized to our needs. @steven. take a look into this http://www.cardesign.ru/articles/projects/2010/7/8/4040/ Propsal: so how about using such small cars in a connected chain behind a bus? for those who don’t have those small vehicles and won’t need them (because the desired place to be is next to the line or a stopover) still can use the bus and the others just connect to the empty slot or connect behind the last one and let the bus do the job of pulling and the busdriver the job of maneuvering. your navigation system notices that you are "connected" and reminds you when to jump off (disconnect) from that big ride to do the final part of the ride on your own again.
  11. For Brian at his Q&A1: like Uncle Ben said in Spiderman 1: Remember, with great power comes great responsibility. Cars for instance are designed to be very very safe. In Germany there is a delegation which prooves cars and their safety and decides whether or not they will get allowance to drive on german roads. BUT in other countries, India for example, they are building cars which are lighter in weight and with less development in safety and design and therefore they are cheaper and more dangerous. However they do work fine as well – you just don’t want to see them after an accident.
  12. Which brings me to my last point - the relation between speed and safety - between power and responsibility: I found it interesting over the last couple of years that there has been a wind of change. Take a look at Twikes ( http://en.wikipedia.org/wiki/Twike ) and SAM ( http://www.elemo.eu/ ) and even the Smart which is used in Austin for car sharing ( http://www.car2go.com/austin/en/ ) They are smaller, maybe even slower but doing their job just fine - a little bit more sustainable and ecological. But after the last sudden increase of price in oil people and then of course the automobile industry started to take a look into alternatives and taking them serious. Conclusion: basically we only would need to have a few cars (like suites or dresses in the wardrobe) and pick for the right situation the right kind of solution. ;) To end with another idea to think about: couldn't a jet-pack for everyone solve the transportation question ? :) have a great weekend everybody!
  13. This might actually be a no-issue. As matthias pointed out, the real issue is planning that allows cities to have all traffic ocur during rush hour in one direction. But even if a city is already set up like, there is a case to be made for all day high frequency of busses even if they are not at capacity. People will only switch from cars to transit if it is convenient to do so, you can't guilt trip anybody into taking the bus. That means that the transit system has to be able to reliably provide any trip that people would make during the day. They have to know that if they need to get from A to B, then they can get there regardless of whether it is during rush hour or not. Thus it is important to provide this service, and in way the rush hour traffic is suppossed to subsidize the all day frequency, just like busy routes help subsidize less busy ones. But if you don't provide these services anymore, then it won't provide the necessary transit needs anymore and might loose critical mass, causing a down spiral of ever increasing service cuts which will first sacrifice the reliability and later the network itself. What you will be left with is a couple of corridors providing rush hour service but few people who can actually rely on it.
  14. Ant6n, Agreed, but we're talking about ideal vs. reality. The ideal is exactly what you say. Ideally, we shouldn't care if vehicles are 75% empty 75% of the time. Providing fast, reliable, frequent service is (presumably) how to get people to use transit. Problem is, transit is expensive. Very expensive. Worse still, it loses hundreds of millions of dollars. If transit made money (or at the very least, lost less money) it would be easier to get cities to invest in the infrastructure. But as long as the economics of transit are as tragic as they currently are, there will always be long, protracted battles about what technology gets built where. I'm basically arguing that fixing transit means fixing the economics first.
  15. Hotels and Airlines have all the same problems. And Public transit agencies in Asia make actually a profit using traditional buses, and trains. The point is transit is an economy of scale. A certain level of ridership and population density is needed to make transit profitable. Low density developments like in North America make it almost impossible to make transit profitable. To many origins and destinations. to long distances and not enough riders. If you build car friendly cities for sixty years the result is that you are dependent to cars. On the other side London, Paris and Tokyo are dependent on their underground trains. Riding a car in those cities is very expensive and not practical at all. There the economics of cars are bad.
  16. Another point, but one often overlooked is the external benefits of quality transit, but are rarely or difficult to internalize into transit infrastructure. Property development benefits, increasing density and allowing more business agglomeration = economic growth, clustering work, live and play destinations (but takes time), travel time savings and access to labor markets, tourist friendly cities, and better quality of life etc. These sound all very fluffy and nice, and not all can be internalized into internal operating costs. But the point I am making is that transit doesn't have to be profitable if these external benefits are taken into account. But the public and politicians have to acknowledge these benefits and factor them into decision making! People have to realize that city building does not happen in political terms, if cities have a urban form that reflects 60 years of road building and cars, it takes time to change that...
  17. Very true, Matthais. But we're still talking about a question of economics. Asian megacities can afford to build transit because of the economies of scale their built form creates. North American cities typically don't have that. The conundrum is this: To get people to use transit, you need more of it (presumably). But to effectively scale up a service, you require it to post a profit (or at least minimal losses). In other words: You need riders to make transit profitable but you can't get riders until you have transit. It's the old "can't get a job without experience but you can't get experience without a job" problem. So what's the solution?
  18. Jarret @ HumanTransit proposes some ideas, mostly related to consolidating parallel lines and buildling networks. I believe it's also important to time connections. Also, for lines that cannot be served with high frequency, I belive an all-day fixed frequency is a possible solution. This means that you can travel at any time during the day (which means you can rely on the service). But more importantly, it creates a schedule that can be remembered easily. If a service comes at 03, 23, 43 every hour, you really only need to remember that it comes on minute 3, every 20 minutes.
  19. @Ant6n: we got that time-remind-simplifier you mentioned in my city (population of 600.000 people). works fine, but it doesn't fix the peak time issue - especially it doesn't create any capacity but only less full platforms at its best. there are two facts about folk like us in public transportation, which make the rules: 1. on the one hand people are willing to accept ANY kind of circumstances AS LONG as we reach our destination (of course you could have waited for 20 minutes and catch the third train - but you didn't). 2. what we won't accept is NOT taking the transportation because it is already full - unless it is full for real. 3. and what we hate most is to wait for our ride - especially when there is a delay (because in our society - especially the western world - we are expected to just function very efficient and precisely and therefore the things we use have to fulfill those expectations too). So describing a train/tram or else as "full" is probably just our western way of perspective. In China staff is pushing people into the waggons - until they are full for real. Thinking about it and experiencing it: I wouldn't mind to endure the price of being transported. But would it be the same, when I earn more money, wear clothes that can't be worn in the mentioned situation or go there with my kids? So the basic question is: how good/bad has the quality of transportation to be? And since quality is the whole package of comfort, efficiency and safety (to some people even ecological) as in the end of course the financial aspect there are a lot of factors which let me intend to say that our standard is much too good. According to that declaration I have to add that it is more a comparative conclusion. As is the fact that we (people of western countries) globally can't keep our standards within the next decades (for example working hours and the standard of living) - which somehow will result in the quality of the services we use. Being lucky or not: under ideal conditions in the end you get what you've paid for! That may sound all a little bit to far away from the actual topic, but as you all know it all comes down to money as the final factor and to what we are willing to bear: what do you think about this? --> http://www.telegraph.co.uk/travel/travelnews/7864921/Ryanair-to-sell-5-tickets-for-standing-room-only-flights.html @Steven: for most asians owning a car is by far too expensive and since all those cities are overpopulated you have a massive amount of people which HAVE to use the public transportation - which makes it really EASY for urban infrastructure planners or the authorities. With a hint of sarcasm I'd say almost any solution would work. @the roots we are talking about: urban planning! I totally agree with what was mentioned a couple of times before. Being familiar with urban design and a lot of cases of urban planning in action by even the best urban planners I have to tell you that most of those good intentions are NOT going to become real. All that you've mentioned earlier is true and people tried to aim for that ideal, but there are just too many factors you simply can not incorporate because the actual development of an area is going to happen in future - and very slow. An outcome: there are two options taking place. 1: let the city grow and then make the arrangements. Good example is the urban progress Lyon made the last decade. 2: plan the whole thing and you may be so infinitely wrong. (Good) example is german Frankfurt (Main). A lot of skyscrapers in the actual city center are empty for over a decade. Similar case: a nearby district was built and not functional over a bunch of years and they finally decides to scale it down by removing buildings and levels of buildings. If possible and suggestive some office buildings were converted to residential buildings. (forgot the name of that district, but if needed I can find out again). well, sometimes there is a third option which is probably the best, but it rarely happens urban planners provide the actual needs of areas and space an urban transportation solution would need. That much flexibility of course has its costs. Having and keeping that option seems to be out of visional range for investors. (which I can understand, but which also is a pity).
  20. just a few quick thoughts to add to this post: zoning: more like the euro model where light industry is interspersed throughout residential neighborhoods. workweek: make four-day workweeks a part of city legislation for urban environments vansharing: - fees become a city fee just like water and sewer, one seat per household - to-from hub destination bus-front marquee signs on each van to simplify ride-sharing - neighborhood hub electric van docks where charging is completely automatic - traffic navigation screen in every van

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