Saturday, May 16, 2009

33> In Defense of the “Track-on-the-Bottom” Design

After my last post I received and email from an industry insider in defense of the track-on-the-bottom design who gave me some facts and figures to chew on. One of those, the proposed height for the stations gave me cause to pause. It was much lower than I had envisioned. This got me thinking. What is the lower limit on raised station height?

One of the problems I have pointed out about bottom track design is that track descending to ground level would block driveways and invite climbers and graffiti. But what if the track only descended to, say, 9 ft.? It would still block some driveways from tall trucks, but the impact would be much less than going to ground level. A “not so raised” station would presumably be much cheaper to build. It’s a thought worth considering.

I still believe in the hanging vehicle approach, personally, but I don’t pretend to have a business model for it at this time. Companies don’t need to solve the whole “transportation/traffic/climate change/wasted productivity/polluted world” thing to have a viable product. A PRT system for (fairly) flat, high volume urban areas is a viable and needed product. It’s not all things to all people, but it is a foot in the door. I think we could call that “PRT I,” and what I am thinking about “PRT II.” I will be glad to see any kind of PRT take root, but those companies should be preparing for PRT II, (not necessarily my design, but the expanded role and capabilities) even as they endeavor to sell PRT I. That is simply keeping ahead of the curve.

As for my design work, I am still hard at it, although I have little internet access and even limited electricity for the time being, as I am at my cabin. I have been designing the old fashion way, with pencil and paper. I will say, though, it looks very promising. Very tight turning radii both vertically and horizontally, very fast speeds, climbs of any angle, (right to vertical) great acceleration and braking. Beside the gondola design, one thing that sets my designs apart from the status quo is the articulated drive unit, which is for better traction and tighter turns. A two part unit will have twice the wheels. Add to that that my switching scheme requires redundant wheels and now you have a drive unit that is bristling with wheels, all needing sizing and placement. This could take a while. So, from the town library in beautiful Canaan, NH, this is Dan, signing out!


Bengt Gustafsson said...

I don't see any big improvement with a partially elevated station. At least not from an ADA perspective. You still can't negoitate 9 feet with a wheel chair wihout elevator. I can not recommend the scheme adopted at a new bird watching tower near here:

I saw it today and the wheel-chair ramp is an ugly and unwieldy structure meandering through the forrest. Ending up at a level of about 9 feet or maybe a little more. This is ADA-compliance gone wild. (There were also plaques with texts in Braille along the foot-path for all the blind bird watchers out there). This is not to say that ADA issues can be neglected but rather that this must be done right.

Another advantage with a suspended system, which may seem minor, but I think can prove important is the ability to let over-height trucks pass (closing PRT traffic temporarily). This is obviously not possible with a supported system.

akauppi said...

Have you considered the chance of using elevators for a track-down design? It can be done, and it can be done lightly. To me, that seems like the best overall design.

Dan said...

Dan the Blogger responds-
Bengt, this next post is for you..