[Sosfbay-discuss] A cheaper, greener transit system: PRT (Personal Rapid Transit)

[Drew Johnson]

Rob Mean's discussion of Personal Rapid Transit at the recent East Valley
Local's showing of "How Killed the Electric Car" got me curious so I did
some research and here's a little bit of what I learned:

PERSONAL RAPID TRANSIT: Briefly what is PRT?
PRT a cheaper, Greener transit system
Mass Transit without the Mass
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PERSONAL RAPID TRANSIT ... PRT runs on fixed guideways, goes 24/7, each
little car carries 1-6 passengers, has service on demand not on a
schedule, no human drivers, and the tracks can be overhead, underground or
on the surface. PRT advantages: low cost, attractive to tourists, relieve
traffic better than any highway widening could ever hope for, and it would
look nice too.   A cost of 1/3 a bus or light rail system, 1/10 BART is
expected.

http://en.wikipedia.org/wiki/Personal_rapid_transit
http://www.electric-bikes.com/prt.htm
http://faculty.washington.edu/jbs/itrans/gorancomp.htm
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http://kinetic.seattle.wa.us/prt.html
PRT a cheaper, greener transit system

Personal Rapid Transit, or PRT, is an inexpensive mass transit technology
that borrows the best features of the automobile (on-demand, non-stop
travel, from anywhere TO anywhere), but glides above traffic like a
monorail. A fleet of small automated vehicles, each seating 3-6 people,
will travel on overhead guideways linking many small stations scattered
throughout an urban area. All points in a city or metro area with such a
PRT network would be close to a PRT station. By being fast and convenient,
PRT stands the best chance of reducing traffic congestion--especially in
the western United States where buses and train systems have all failed in
that regard. Why trains don't relieve congestion.

Cost Advantage

Where conventional "light-rail" and "monorail" trains are restricted to
corridors, PRT systems would be laid out in a grid pattern extending in
any direction.  This is made possible by a straightforward logical
sequence: Small, lightweight vehicles are cheaper than  large, heavy train
cars; the lighter weight means the PRT guideway can be lighter and
less-intensively engineered than conventional railbeds, elevated rails or
monorail beams; lighter, simpler guideway means quicker, cheaper
construction. (See chart) Thus on a per-mile basis PRT is dramatically
cheaper to build than trains. Therefore more miles of PRT guideway can be
built for less money. 3 Examples


Think public transit is a hassle? Here is PRT's Elegant Solution

The guideway network's grid pattern, made possible by PRT's cost
advantage, is what makes PRT superior to conventional trains as a mode of
mass transit. PRT guideways would be spaced at ½-mile intervals; small
stations with 1 or more berths would be located off-line (meaning PRT pods
pull off the route to board/unboard passengers, out of the way of other
pods) every ½-mile.  This station distribution pattern means you and your
destination are never be more than ¼-mile away (an easy walk, only 440
yards) from a PRT station. This high degree of accessibility is a PRT
advantage that light rail and monorail cannot match.

Green Transit
Personal Rapid Transit is inherently more energy-sustainable, or
"greener," than automobiles and conventional transit. The key to PRT's
lower energy usage is its small size (translating into light weight),
non-stop service (eliminating most energy-wasting starting and stopping),
and on-demand service (PRT vehicles don't move until needed). The table
shows how PRT measures up (other data is from the USDOT "Transportation
Energy Databook," 24th Edition, Ch. 2, p.13):

Mode 	BTUs per passenger mile
PRT1	834
Vanpool	1,362
Motorcycle	2,274
Commuter rail	2,714
Rail transit	3,268
Auto	3,581
Commercial air	3,703
Personal truck	4,057
Bus transit	4,127
Amtrak	4,830
1. ULTra, ATS Ltd.


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http://www.gettherefast.org/masstran.html
PRT: Mass Transit Without the "Mass"

Imagine that, instead of a single huge bus, all these empty seats could
run around separately (or in sets of 2, 3 or 4), picking up people
on-demand and transporting them non-stop to their destinations. The result
would still be MASS transit, except now it would be individualized—or
PERSONAL.

We're all familiar with conventional transit—large vehicles that run on
timetables, stopping at designated locations. Show up at the appointed
place, hope the system is running on schedule, and you and a lot of other
people ride the route together. The primary problem with this type of mass
transit is that the "mass" is mostly vehicle mass, not people mass.

PRT turns the conventional formula on its head. PRT begins from the
observation that automobiles don't operate on timetables, so why should
transit? By running when YOU want to travel (demand-responsive, or
"on-demand"), PRT takes the large groups of bus or train riders and
spreads them out over time, like this:

{Graphic showing how 65 people can ride in an hour via 3 bus trips or
multiple PRT trips}

Same numbers of people, but in PRT they get to travel at their
convenience, and the ride is private or with others of their choice. Is
this efficient? Yes—with PRT, vehicles only move when someone needs one.
Buses and trains have to keep to their schedules even when partially
full—and even when empty. Is PRT cost effective? Yes—three buses might
cost $500,000 each. In the above table of 41 PRT trips, the 65 people
could be served by only 10 PRT vehicles costing $10-20,000 each.

Only 10!? Because PRT doesn't force everyone to travel together, each of
the 10 vehicles can pick up riders, drop them off, then pick up more. This
sharing of vehicles by riders in succession is the key to PRT's total
carrying capacity, and it's possible because service is on-demand. One PRT
vehicle can make 5, 6, or even more separate journeys per hour, depending
upon average trip length. But because PRT travels nonstop at 20-45 mph the
entire way, each trip will usually be short. Thus, if one vehicle makes 6
trips per hour...


# vehicles 	Trips per hour
20 	        120
100	        600
500	        3,000
5,000	        30,000

If we assume an average of 1.2 persons per trip (about the same as cars),
the 5,000 vehicle fleet can have a maximum hourly ridership level of
36,000 people, or 864,000 per day. For comparison, consider that total
weekday bus ridership for all of King County averages about 313,000.