question about a bus bridge
msh210
St. Louis (Mo.)'s light rail, Metrolink, currently uses a bus bridge
east of its CWE station, so e/b trains terminate at CWE and continue w/
b. Now, the station has one platform: e/b and w/b trains use the two
sides of the same platform. There are switches to the east _and_ to
the west of the station that allow trains to move from the e/b to the
w/b tracks or vice versa.
What they're doing is having the e/b train come into the e/b track at
CWE, pull e/b out of CWE, come back to the w/b track at CWE, and
continue w/b on its route. (Signs are switched while it's sitting in
the station on the e/b track, I think.) This makes no sense to me,
for a couple of reasons: (1) Waste of effort versus pulling into
_either_ track and pulling right out again (i.e., switching west of
CWE). (2) East of CWE, before the switches, it grade-crosses roads,
unnecessarily disrupting traffic.
You might think it's necessary to do it this way, as it allows more
traffic: while a train is switching east of CWE, another can pull in.
But I'm pretty sure the trains don't run frequently enough for it to
matter.
I asked an employee (I think a motorman) why they do it the way they
do, but he was unable to give me an explanation I could understand.
Any ideas?
Michael Hamm
Robert Bonomi
msh210 <msh...@gmail.com> wrote:
>
>What they're doing is having the e/b train come into the e/b track at
>CWE, pull e/b out of CWE, come back to the w/b track at CWE, and
>continue w/b on its route. (Signs are switched while it's sitting in
>the station on the e/b track, I think.) This makes no sense to me,
>for a couple of reasons: (1) Waste of effort versus pulling into
>_either_ track and pulling right out again (i.e., switching west of
>CWE). (2) East of CWE, before the switches, it grade-crosses roads,
>unnecessarily disrupting traffic.
>
>You might think it's necessary to do it this way, as it allows more
>traffic: while a train is switching east of CWE, another can pull in.
>But I'm pretty sure the trains don't run frequently enough for it to
>matter.
>
>Any ideas?
As with anything, there are a combination of things going on. And how the
_relative_ merit/importance of those things is weighted affects how the
decision is made.
Loading and unloading on different sides of the platform _does_ eliminate
a lot of platform congestion. Not only does it physically separate the
arriving passengers from the departing ones -- making for a clearer path
to the street for the arrivals -- but it _temporally_ separates them as
well.
Secondly, if all you have 'behind' the station is a stub track, there's
only -one- switch that needs to be thrown when the train reverses. While
switching 'in front of' the station requires two switch throws (one on
each track).
Thirdly, the motorman has to get from one end of the train to the other
to operate in the reverse direction. It's a _lot_ easier, and probably
somewhat _faster_ to do this when there are no passengers on board. And,
the no-passengers walk-through gives the crewman more of a chance to
spot any of a number of kinds of possible problems.
Their might be union rules involved. Or the two sets of switches may
be operated from different locations. With only one of them routinely
being staffed.
And, then there's Tevye's inarguable rationale: "Tradition!"
*LOTS* of possibilities, in short. <grin>
msh210
> there are a combination of things going on.
...and a lot more. Thank you, R.B.
One small note:
R.B.:
> Loading and unloading on different sides of the platform _does_ eliminate
> a lot of platform congestion.
Yes, but the whole system, and this station in particular, isn't so
busy that I think it'd make a big difference. (Frankly, I don't know
how they're surviving.)
One more factor, I suppose, is the need to temporarily reteach people
to board a w/b train on the usually-e/b side of the platform.
Michael Hamm
Stephen Sprunk
> Yesterday, Robert Bonomi wrote:
>> Loading and unloading on different sides of the platform _does_
>> eliminate a lot of platform congestion.
>
> Yes, but the whole system, and this station in particular, isn't so
> busy that I think it'd make a big difference. (Frankly, I don't know
> how they're surviving.)
Subsidy, just like every other transit system in the US. None are in
nearly enough financial trouble to need to shut down, though many have
cut back service somewhat to stay current on their bond obligations.
> One more factor, I suppose, is the need to temporarily reteach people
> to board a w/b train on the usually-e/b side of the platform.
DART does this at five of its seven terminal stations, and nobody seems
to be confused by it. There is a scissors crossover before the (always
center, at terminals) platform, and arriving trains go to whichever side
is currently empty, then change their destination roll signs to indicate
the other end of the line. The TOs leave the passenger doors unlocked
and go inside the station for a food/drink/restroom break. Assuming all
the trains are on schedule (which is quite normal for light rail), it
will depart within a minute after the next one arrives. The fixed signs
on _both_ sides of the platforms indicate the far end of that particular
line, so it's pretty easy to figure out. It's not like any of these
stations have unusually high passenger volume, so I must conclude that
DART did it that way because it's simpler for them to operate.
At most of the terminals where there are storage tracks, there is no
crossover on that side of the platform, and no passengers seem to get
confused. Then again, the and of the line is quite visible to anyone
who bothers looking.
Victory Station is an oddity in many ways, using center _and_ side
platforms to handle the flash crowds there, but even that doesn't seem
to confuse anyone, despite not being consistent with the rest of the
system. Some peak hour trains end/turn at Cedars Station, which has a
pocket track nearby, but that's also where a yard lead joins, so there's
all kinds of screwy movements there.
S
--
Stephen Sprunk "God does not play dice." --Albert Einstein
CCIE #3723 "God is an inveterate gambler, and He throws the
K5SSS dice at every possible opportunity." --Stephen Hawking
David Lesher
>> a lot of platform congestion.
As a WMATA rider, I was jealous of Atlanta where the nexus station,
at least, had an exit platform on one side, and entrance on the
other. As I recall, the exit served both directions.
Only a very few WMATA stations were/are triple track to allow same.
One, National Airport, used to be such but the switches were ripped out
of the south end recently.
--
A host is a host from coast to coast.................wb8foz@nrk.com
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Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433
rsh...@gmail.com
> >> Loading and unloading on different sides of the platform _does_ eliminate
> >> a lot of platform congestion.
>
> As a WMATA rider, I was jealous of Atlanta where the nexus station,
> at least, had an exit platform on one side, and entrance on the
> other. As I recall, the exit served both directions.
>
> Only a very few WMATA stations were/are triple track to allow same.
> One, National Airport, used to be such but the switches were ripped out
> of the south end recently.
>
It is a crying shame when they built the Washington Metro in the 70's,
they could not afford express tracks for the red line.
Could you imagine the capacity increase possible if they could run
expresses to Shady Grove for instance.
another instance of failure to plan for the future
Jimmy
> DART does this at five of its seven terminal stations, and nobody seems
> to be confused by it. There is a scissors crossover before the (always
> center, at terminals) platform, and arriving trains go to whichever side
> is currently empty, then change their destination roll signs to indicate
> the trains are on schedule (which is quite normal for light rail), it
> will depart within a minute after the next one arrives. The fixed signs
> on _both_ sides of the platforms indicate the far end of that particular
> line, so it's pretty easy to figure out.
How do passengers know which train is leaving first?
In Boston, the Alewife terminal operates this way. It originally had
signs that would light up to show which train was leaving next, but
the lights were often broken. And then in a recent sign replacement
project, they removed the "next train" text entirely.
It's *usually* easy to figure out which train is next: if both tracks
are occupied, the one with more people on it leaves first. But at
very quiet times of day, it's not so easy to tell. And sometimes a
train will arrive so late that it will leave before the other train
which was already sitting there. When that happens, they usually
leave the doors shut on the train that's leaving second, or make an
announcement, but not always, and sometimes people get left behind.
Jimmy
Stephen Sprunk
> Stephen Sprunk <step...@sprunk.org> wrote:
>> DART does this at five of its seven terminal stations, and nobody seems
>> to be confused by it. There is a scissors crossover before the (always
>> center, at terminals) platform, and arriving trains go to whichever side
>> is currently empty, then change their destination roll signs to indicate
>> the other end of the line. ... Assuming all
>> the trains are on schedule (which is quite normal for light rail), it
>> will depart within a minute after the next one arrives. The fixed signs
>> on _both_ sides of the platforms indicate the far end of that particular
>> line, so it's pretty easy to figure out.
>
> How do passengers know which train is leaving first?
The destination roll signs on the arriving train don't change until
after the departing train is gone, plus there are announcements for the
blind.
If the passengers don't notice either, the departing train's doors will
also usually be open, while the arriving train's will be unlocked but
shut (i.e. they can be individually opened by a passenger pressing a
button, but will not be as inviting as the other train with open doors).
Even the most clueless passengers will follow the path of least resistance.
David Lesher
>It is a crying shame when they built the Washington Metro in the 70's,
>they could not afford express tracks for the red line.
>Could you imagine the capacity increase possible if they could run
>expresses to Shady Grove for instance.
>another instance of failure to plan for the future
More so on the under-construction Silver Line. And IMHO, they don't need
4-track; they could make major improvements with just a common passing
track around the stations.
1100GS_rider
> msh210 wrote:
> > Yesterday, Robert Bonomi wrote:
> >> Loading and unloading on different sides of the platform _does_
> >> eliminate a lot of platform congestion.
> >
> > Yes, but the whole system, and this station in particular, isn't so
> > busy that I think it'd make a big difference. (Frankly, I don't know
> > how they're surviving.)
>
> Subsidy, just like every other transit system in the US. None are in
> nearly enough financial trouble to need to shut down, though many have
> cut back service somewhat to stay current on their bond obligations.
Every year that I lived in the St. Louis area, Metrolink threatened to
shut down unless its subsidy was increased. Gets boring after a while.
rsh...@gmail.com
> "rshe...@gmail.com" <rshe...@gmail.com> writes:
> >It is a crying shame when they built the Washington Metro in the 70's,
> >they could not afford express tracks for the red line.
> >Could you imagine the capacity increase possible if they could run
> >expresses to Shady Grove for instance.
> >another instance of failure to plan for the future
>
> More so on the under-construction Silver Line. And IMHO, they don't need
> 4-track; they could make major improvements with just a common passing
> track around the stations.
> --
the problem is, as I am sure you are aware, they only built the
tunnels and structures wide enough for two tracks.
that is the beauty of the NYC subway, esp the ind
great planning to handle millions of people
rsh...@gmail.com
and how long have they screwed around with the new Miss R Br because
MO has refused to raise its gas tax to fund it?
and while I am at it, I don't live anywhere near St Louis
why should my fed gas tax go for a new Miss R Br???
If you want it so bad, you pay for it