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Re: [carfree_cities] Bargain-basement underground transport?

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  • J.H. Crawford
    ... This may have some merit, especially in small projects where a full-scale metro would be too expensive. It should be designed so that a EuroTram can run it
    Message 1 of 11 , Feb 7, 2004
      Erik Rauch said:

      >The great advantage of the metro is its grade-separated, dedicated right
      >of way. But tunnelling and underground stations, though cheaper in a new
      >development than in an existing city, are still expensive. In building a
      >new carfree area where money is scarce, could one simply dig a shallow,
      >cut-and-cover tunnel and run self-guided vehicles through it, of the type
      >described in the January 2004 Carfree Times?

      This may have some merit, especially in small projects where a
      full-scale metro would be too expensive. It should be designed
      so that a EuroTram can run it in (these are low-floor and thus
      not a lot higher than 2 meters). These are run underground for
      a kilometer in Strasbourg and function just like a metro in this
      instance, except for not being as fully powered, with resultant
      modest acceleration and low top speed, neither of these a real
      problem.

      >At its most basic, the tunnel
      >could be nothing more than a trench covered by grates.

      This is really about what's proposed in Carfree Cities, in the
      Moving People chapter. The structure above has to be enough to
      carry the weight of whatever traffic is allowed in the area.
      It closely resembles what's proposed for metro-freight, except
      that the required clearances are not as great for a EuroTram.

      >Crossing lines would need to be handled, but with automated
      >guidance, it should be possible to do this at the same grade, avoiding the
      >need for tunnelling under a trench.

      Don't like this, as it's a serious risk for collision.
      Ideally, topologies don't call for crossing lines; rather,
      lines are brought alongside each other for transfers.
      Crosses can't be avoided in very large cities, but are
      otherwise not always needed.

      >This idea has some things in common
      >with a people mover, but without the drawbacks of elevated structures.

      yup

      >Though not as nice as a full-blown metro, such a system, if feasible,
      >would have some of the most important advantages that the metro has over
      >surface transport - even trams.

      Grade separation is extremely desirable.

      >I wonder if such a system would be feasible and indeed be significantly
      >cheaper than a metro.

      No hard numbers, but I think so.

      Regards,




      -- ### --

      J.H. Crawford Carfree Cities
      mailbox@... http://www.carfree.com
    • Richard Risemberg
      Most Metros are built using cut-and-cover these days, I think. The system you envision would not have the capacity of a metro. Even LA s Metro Red Line (the
      Message 2 of 11 , Feb 8, 2004
        Most Metros are built using cut-and-cover these days, I think.

        The system you envision would not have the capacity of a metro. Even
        LA's Metro Red Line (the other lines are surface light rail) can carry
        800-1000 passengers per train, and rush hour trains are pretty full.
        New York's and some of Tokyo's can carry more, with headways as low as 3
        minutes sometimes. Small stations limit train size, so you just end up
        with an underground bus--in which case you may as well just have busways.

        My 2 cents.

        Richard

        Erik Rauch wrote:
        > I don't know much about transportation engineering, but pondering why a
        > metro is expensive brought to mind a possible alternative.
        >
        > The great advantage of the metro is its grade-separated, dedicated right
        > of way. But tunnelling and underground stations, though cheaper in a new
        > development than in an existing city, are still expensive. In building a
        > new carfree area where money is scarce, could one simply dig a shallow,
        > cut-and-cover tunnel and run self-guided vehicles through it, of the type
        > described in the January 2004 Carfree Times? At its most basic, the tunnel
        > could be nothing more than a trench covered by grates. The small size of
        > the vehicles would require only a shallow tunnel: the vehicles can be only
        > about 2 meters high. Stops could simply be pits with stairs surrounded by
        > fencing. Crossing lines would need to be handled, but with automated
        > guidance, it should be possible to do this at the same grade, avoiding the
        > need for tunnelling under a trench. This idea has some things in common
        > with a people mover, but without the drawbacks of elevated structures.
        >
        > Though not as nice as a full-blown metro, such a system, if feasible,
        > would have some of the most important advantages that the metro has over
        > surface transport - even trams.
        >
        > I wonder if such a system would be feasible and indeed be significantly
        > cheaper than a metro.

        >


        --
        Richard Risemberg
        http://www.living-room.org
        http://www.newcolonist.com

        "I believe that every right implies a responsibility; every opportunity,
        an obligation; every possession, a duty."
        John D. Rockefeller, Jr.
      • J.H. Crawford
        ... Not always; here in Amsterdam, world capital of soupy soils, they are going to bore the new metro deep underground using a tunnel boring machine. Metros
        Message 3 of 11 , Feb 9, 2004
          Richard Risemberg said:

          >Most Metros are built using cut-and-cover these days, I think.

          Not always; here in Amsterdam, world capital of soupy soils, they
          are going to bore the new metro deep underground using a tunnel
          boring machine. Metros close to the surface probably are built
          mostly with cut-and-cover, but many have to be deep in order to
          clear existing underground works.

          >The system you envision would not have the capacity of a metro. Even
          >LA's Metro Red Line (the other lines are surface light rail) can carry
          >800-1000 passengers per train, and rush hour trains are pretty full.
          >New York's and some of Tokyo's can carry more, with headways as low as 3
          >minutes sometimes. Small stations limit train size, so you just end up
          >with an underground bus--in which case you may as well just have busways.

          Not necessarily; the EuroTram is nearly as wide as a metro car and
          can be lengthened as needed to reach about the same capacity for a
          given length of boarding platform/train. It has to do more with the
          designed capacity than the particular mode.

          And, of course, any system in a tunnel avoids street traffic.

          Regards,



          -- ### --

          J.H. Crawford Carfree Cities
          mailbox@... http://www.carfree.com
        • Matt Dobbing
          Hello all In response to discussion about energy provision for a car free city Jim Dyer wrote work on the city s infrastructure, particularly the
          Message 4 of 11 , Feb 9, 2004
            Hello all

            In response to discussion about energy provision for a car free city Jim
            Dyer wrote

            'work on the city's infrastructure, particularly the transportation
            infrastructure,
            so as not to waste so much energy in the first place'

            I agree with this and it should be a central concept in 'green' design.
            simple design features such as a rise into a metro station and a fall out of
            it save energy on deceleration and acceleration and can easily be
            incorporated as the infrastructure is put in place.

            Matt Dobbing

            _________________________________________________________________
            Get some great ideas here for your sweetheart on Valentine's Day - and
            beyond. http://special.msn.com/network/celebrateromance.armx
          • Patrick McDonough
            I had to link to this... http://www.theonion.com/4005/news1.html
            Message 5 of 11 , Feb 9, 2004
            • mauk_mcamuk
              ... How is this off-topic? You gotta power that huge rail system with something, right? Have to keep the lights on in all those high- density housing units.
              Message 6 of 11 , Feb 9, 2004
                --- In carfree_cities@yahoogroups.com, Jym Dyer <jym@e...> wrote:
                > > I mean, how would you power a carfree city? 100 percent
                > > windmills? It'd never work. Tuck in a pair of nuclear plants
                > > out in the industrial districts and now you're talking! :)
                >
                > =v= I'm not going to rehash an off-topic nuclear power debate
                > on this list.



                How is this off-topic? You gotta power that huge rail system with
                something, right? Have to keep the lights on in all those high-
                density housing units. Got to keep the economic engine ticking over
                reliably, right? Magical pixie-dust power won't cut it.

                Also, to be honest, cars use a fairly small percentage of the USA's
                energy. A modern industrialized economy is a hungry mother, and
                unless we want to look at radical changes in the economy even beyond
                ditching the automobile, we're going to have to feed the economy lots
                of energy.

                Here, check this .pdf:

                http://eed.llnl.gov/flow/pdf/ucrlID129990-00.pdf

                That paper shows that in 2000, the USA consumed a total of 98.5
                Quadrillion BTU's of primary energy. Of that, only 26.6 Quads was
                used for transportation, and even carfree cities won't displace all
                of that.


                > Anything I might have to say on the matter was
                > said 30 years ago by Amory Lovins, and about the massive costs
                > of decommissioning in particular, 20 years ago by Karl Hess.
                >

                So, you're basicaly stuck in the past and have no defense for your
                baseless comments? :)

                How about a more up-to-date look at things:

                http://www.nei.org/doc.asp?docid=501

                According to that paper, $22.5 billion has been set aside already to
                decommission the US nuclear fleet, with many more billions to come.
                This is money charged to you, me, and everybody else who uses nuclear
                electricity, and is not charged to the government.


                > =v= As for what I'd so, it's the same thing I've been saying
                > for the four years I've been on this list: work on the city's
                > infrastructure, particularly the transportation infrastructure,
                > so as not to waste so much energy in the first place. That way
                > they can be powered largely, if not totally, from clean energy
                > sources.


                Name said sources, please.

                Windmills? Excellent powersource, except that wind has low capacity
                factors and is intermittant.

                Hydro? Wonderful source of power, except it has stringent siting
                issues, and droughts can be worrisome.

                Solar? Passive solar thermal is on the ragged edge of viabillity,
                photovoltaic is completely out of the question.

                Natural gas? Seen the price of gas lately? :)





                > <_Jym_>
                > --
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