Here's some fun transit-comparison math.
David Brauer quoted the Pioneer Press:
>If you were hoping the new $548 million light-rail line slated to stop at
>the Metrodome in downtown Minneapolis would ease traffic after a Vikings
>game, expect your hopes to be dashed.
>
>The one line - which is planned to run from downtown Minneapolis out of the
>city and along Hiawatha Avenue to the Mall of America in Bloomington - won't
>help much in shuttling folks from Dome events. The line can only handle
>about 3,000 people over the course of an hour - and that's only if every
>single rail car works and is filled to capacity.
Just for comparison, folks, here's the PRT version: If we had a PRT line
instead of light rail in the Hiawatha corridor (for $250 million, not
$625 million and counting), a single line could take 3 vehicles per second.
Assume an average post-game occupancy of 2 (since the vehicles comfortably
hold up to 3, and people go to games in groups), and you get 6 people per
second, or 360 per minute, or 21,600 per hour!
Of course, like the light rail piece, that ignores the problem of loading:
the rail has more capacity than any individual station. But if we built
2 12-berth stations on different sides of the dome, with a reasonable
expectation that they could load once every 45 seconds, that brings us
to 24 cars * 2 people / 45 seconds = about a person per second, or 3600
per hour. (Of course it's reasonable to expect that some people will walk
a 1/2 mile to a nearby station, as they do to their cars, and load there.)
This would also be effective with the $90 million downtown plan I talk
about on my campaign web site (http://www.SteveAnderson.org/issues/prt/),
rather than a Hiawatha PRT line for $250 million. People could use the
downtown PRT system to get to the parking ramps over 394. This wouldn't
get them home, but it would have a significant impact on traffic -
just crossing downtown can be a major hurdle.
What conclusions can we draw so far?
- PRT has far greater capacity on a single line than light rail
- But even so, getting everyone out of a stadium is simply not an easy
problem.
One approach might be to add more station capacity - for more capital
investment - around the metrodome. But Paul had a relevant point here:
At 05:01 PM 10/3/2000 -0500, Paul Barber wrote:
>
>I agree. No one said LRT was the 'be all, end all' solution to everyone's
>transportation needs. It just gives another ALTERNATIVE and should help
>some people attending dome events and relive some road congestion around
>that area.
These are both solid arguments for PRT - but they're weak for LRT. Why?
Because in the maximum-capacity scenario, we'd be sending light rail
trains out every 5-7 minutes. These trains would block traffic at
every street crossing for at least 45 seconds every time they go by.
Include return trains (since you've got to bring them back to fill
them up again), and this becomes a minute and a half out of every 5-7
minutes for most streets they cross. (A few would benefit from having
north and south trains crossing at the same time.)
They would be another alternative, but would they reduce congestion,
tying up all the cross-streets like that? PRT is an entirely elevated
system, and as such places no additional burden on existing traffic
patterns. PRT cars don't have to stop for other traffic, and other
traffic doesn't have to stop for them.
Carol Becker wrote:
>Regarding the Metrodome events and the use of LRT. The question of why this
>is an issue is a good one. 80% of transit riders are riding to get to work.
>75% of transit riders ride during the peak periods of 7:00 - 9:00 am and
>3:30 to 6:30 pm. Transit is basically for two purposes: 1) to get people to
>work during peak periods and 2) to provide a basic level of transit for
>people who have no other alternative. Neither of these functions has much to
>do with providing transportation for special events like the Vikings. As
>such, I would argue that this isn't really a fair criterion to judge the
>effectiveness of LRT.
I mostly agree - I'd say that purpose #1 is really about reducing the need
for auto usage and traffic congestion in general, but the most important
first step is addressing the peak periods. It's simply always going to take
some time to clear out a stadium, as sports and concert fans know - sometimes
it can take a huge amount of time just to clear the human "traffic" out of
the building.
But consider the numbers. The Hiawatha light rail line will be able
to carry a theoretical maximum of 2000-3000 people per hour, depending on
who you ask. A single freeway lane, carrying unsafe vehicles with less
than 1 second stopping distance, can carry over 3600 vehicles (thus people)
per hour. A single PRT line, with average rush-hour occupancy of .8,
and vehicles spaced up to a third of a second apart, can carry .8*3*3600,
or 8640 people per hour.
(I would be remiss if I suggested that it would be able to do so on the
first day out, though - the $250 million Hiawatha alternative I mentioned
earlier includes all vehicles and stations for a starter project, but not
enough vehicles to carry this many people this quickly. But that's fine
- there isn't that kind of demand either, and we can economically add
vehicles as demand grows. That's the maximum the guideway could possibly
support.)
(I also don't mean to suggest that the Hiawatha line is a good candidate
for the first application of PRT. A first application would ideally be
covering a small area that generates a huge number of short trips -
like the downtowns, the University, or shopping complexes like Southdale.
But it could do the job - for less than half the cost of light rail, and
with greater convenience.)
--
Steven C. Anderson 612-722-6658 [EMAIL PROTECTED]
The Independence Party Candidate for Minnesota Senate, District 62
http://www.SteveAnderson.org/
