IRFCA Mailing List Archive

Messages 7941 - 7960

Previous 20 Messages          Archive Index          Next 20 Messages

From: S.SRINIVAS <>

Subject: Re: railway junction with maximum fan-out

Date: 27 Aug 1999 10:02:35 -0500


Dear Apurva

you must consider Bhatinda Jn. as the winner which has six directions in
which rly. tracks go.
all of them from Bhatinda junction itself !!

delhi junction has a count of four only now. there is no MG line
anymore.

s. srinivas

Apurva Bahadur wrote:

> > >Also do you have a winner for the
> > >junction with the most branches ?
> >
> > No: of
> > lines Name
> >
> > 5 DABHOI
> > 5 DELHI
> > 5 GUNTAKAL
> > 5 GUNTUR
> > 5 GWALIOR
> > 5 JALANDHAR CITY
> > 5 KANALUS
> > 5 KANPUR CENTRAL
> > 5 KATIHAR
> > 5 KATNI
> > 5 LUCKNOW
> > 5 MAHESANA
> > 5 MORADABAD
> > 5 PANVEL
>
> Why does Panvel have 5 branches ? I can list - from Diwa, to Konkan
Rly, to New Mumbai, to JNPT and to Karjat (???). Is
> this correct ?
>
> > So, the winner is Mathura. My definition of a junction is very
rigorous and may not agree with IR's. If a line goes
> > A Jn. - B (minor station) - C etc.
> > and another goes
> > A Jn. - B (minor station) - D etc.
> > I take B to be the junction, not A.
>
> In that light is Pune a Junction or is is Ghorpadi (Ghorpuri) where
the lines towards Miraj and Daund start to branch off
> ?
>
> Apurva

From: Vijay Balasubramanian <>

Subject: In defence of slow trains

Date: 27 Aug 1999 10:02:40 -0500


Hi Folks,

A slow express train with frequent halts is the last rung in a
well-structured
gradation ladder - Pushkar has alluded to this earlier. It caters more
to
the
intermediate not-so-important halts and should not be heavily used for
commuting
between the terminii concerned, as long there are sufficient faster
trains
to fill that gap.
I would tend to look at such a train as a concatenation of several
short-distance trains.

Unfortunately, many trunk routes do not have a well-structured gradation
pattern - a missing
link can cause problems -
1. Absence of a superfast/fast train (towards the higher end) places a
heavy
burden on trains
lower down the list and commuters have to suffer agonizingly long
journeys.
e.g. Mumbai-Chennai.
2. Absence of medium-fast trains (with reasonable halts) causes
superfast
trains to be
doused with halts as in the case of Paschim Exp.
3. Absence of slow express trains can cause overcrowding and journeys on
superfast/fast trains can
become a nightmare.

Of course, you can't have superfast/fast trains between all
terminii-pairs
(unless one of them is Delhi :-) )
and so there are two choices - change trains at an intermediate point or
endure the journey. e.g. Mumbai-
Dehra Dun exp. takes about 42 1/2 hrs. A much faster way would be to
take
the Swaraj Exp. till New Delhi
and then hop into the Shatabdi exp. - time taken is about 28 1/2 hrs.
Is
Dehra Dun exp. heavily used by
Mumbai - Dehra Dun folks? It crawls in the daytime and is faster
during
the night indicating that it caters
to the small stations as a day train.

Regards,
Vijay

From: S.SRINIVAS <>

Subject: Re: MR trains

Date: 27 Aug 1999 10:04:30 -0500


dear samit

don't count on this list. it keeps changing. with every new minister,
there
will be a new list.
with no minister (at least no full time minister) in rail bhavan, there
may be
no list!

railfans should not worry about punctuality or "must run" catagory of
trains.
it is always nice to be stranded on a train - as long as the train is
still on
the rails!
cheers.

srinivas

Samit Roychoudhury wrote:

> can someone provide a comprehensive list of MR trains. this seems
> fascinating and i had no idea such a thing existed. might help me
preparing
> journeys later.
>
> thanks
> samit

From: T.H.Sanyal. <>

Subject: Re: Shortest Routes, PRS Mistakes..?! (Suresh, Raymond, Apurva)

Date: 27 Aug 1999 10:37:00 -0500


Larry Webber wrote:

>Thanks. I'm improving it now, I have thought of a few ways of doing so
while
> travelling.

I may be missing something here, but there are standard graph theory
algorithms for finding shortest paths in a network. Why can't those
algorithms be used for IR ? You could put distance information for
junctions and termini in a matrix and use Floyd-Warshall
algorithm to compute shortest paths among all junction pairs. This
would take 10^6 entries which should be ok for a modern PC.

>No: of
>lines Name

>5 KANALUS

Where is KANALUS?

>5 RANAGHAT

Should be 4: towards Kalinarayanpur Jn, towards Gede, towards Bangaon
Jn, and towards Sealdah. From Kalinarayanpur the routes split towards
Shantipur and towards Krishnanagar City.

Regards to all.
ths.

From: T.H.Sanyal. <>

Subject: Re: "MR" category

Date: 27 Aug 1999 10:47:00 -0500


Raymond wrote:

>Another interesting thing that I have noticed is the "must run"
category of
>train. For example, if there are floods, or major derailments which
block the
>normal route, then very few among the normal scheduled trains are
diverted g
>alon
>a modified track, rest are cancelled. I wonder if that still happens.
For
>example, in the late 1970's and 80's there used to be rather frequent
cyclones
>in Andhra, and floods in Maharashtra / Madhya Pradesh. In the
circumstances,
>only the GT and Howrah - Madras Mail used to run through diverted
routes.

I don't know the situation now, but among Calcutta-Delhi trains, the
venerable Howrah-Delhi-Kalka Mail (the old 1 Up/2 Dn) used to be such
a train. I recall that once there was some major track damage on
Northern railway, and this train was running via Jhansi! Even the
Howrah-New Delhi Rajdhani was cancelled (not to speak of lesser trains)
but Kalka mail was still running.

ths.

From: lwebber <>

Subject: Re: railway junction with maximum fan-out

Date: 27 Aug 1999 10:57:16 -0500


> > >Also do you have a winner for the
> > >junction with the most branches ?
> >
> > No: of
> > lines Name
> >
> > 5 DABHOI
> > 5 DELHI
> > 5 GUNTAKAL
> > 5 GUNTUR
> > 5 GWALIOR
> > 5 JALANDHAR CITY
> > 5 KANALUS
> > 5 KANPUR CENTRAL
> > 5 KATIHAR
> > 5 KATNI
> > 5 LUCKNOW
> > 5 MAHESANA
> > 5 MORADABAD
> > 5 PANVEL
>
> Why does Panvel have 5 branches ? I can list - from Diwa,
> to Konkan Rly, to New Mumbai, to JNPT and to Karjat (???). Is
> this correct ?

The line from Panvel to JNPT has a branch to Jasai and Uran. That
branch occurs --BEFORE-- there is any other listed station/halt, and my
program is wholly station-driven. So Panvel-JNPT and Panvel-Jasai count
as two lines... I wondered if anyone would notice... :)

5 RANAGHAT
5 REWARI
5 SABARMATI
5 VARANASI
5 VILLUPURAM
6 BATHINDA
7 MATHURA


> > So, the winner is Mathura. My definition of a junction
> > is very rigorous and may not agree with IR's. If a line goes
> > A Jn. - B (minor station) - C etc.
> > and another goes
> > A Jn. - B (minor station) - D etc.
> > I take B to be the junction, not A.
>
> In that light is Pune a Junction or is is Ghorpadi
(Ghorpuri) where the lines towards Miraj and Daund start to branch off ?

Pune is a Junction (per my definition), as there are distinct lines
leaving it for:-
(a) Shivajinagar (for Karjat/Kalyan)
(b) Hadapsar (for Daund/Wadi)
(c) Ghorpadi (for Nira/Miraj)

As it is more than two, Pune counts as a Junction (for purposes of my
program).

Per my data, Ghorpuri is *NOT* on the line to Daund... am I wrong?
Pune-Hadapsar does not pass Ghorpadi?




# Dear Apurva

# You must consider Bhatinda Jn. as the winner which has six
# directions in which rly. tracks go.
# all of them from Bhatinda junction itself !!

Actually, MATHURA has seven... :-)

You missed my original mail, and Apurva snipped the part after Panvel...


7 Lines from Mathura Jn.:
ACHHNERA
BHARATPUR
KAMAN/ALWAR
KOSI KALAN/BALLABGARH
HATHRAS
RAJA KI MANDI
VRINDAVAN

# delhi junction has a count of four only now.

5 Lines from Delhi Jn.:
DELHI SARAI ROHILLA
DELHI SHAHDARA
NEW DELHI
ROHTAK
SUBZI MANDI


# there is no MG line any more.

Which one of the above does not exist, please?



> Apurva

# s. srinivas


Regards to all

L Webber


------------------------------------------------------------------------
------
Get free personalized email at
<A HREF="http://www.pathfindermail.com/member/login.page">http://www.pathfindermail.com/member/login.page</A>

From: lwebber <>

Subject: Re: Shortest Routes, PRS Mistakes..?!

Date: 27 Aug 1999 11:39:04 -0500


> >Thanks. I'm improving it now, I have thought of a few ways of doing
so while
> > travelling.
>
> I may be missing something here, but there are standard graph theory
> algorithms for finding shortest paths in a network. Why can't those
> algorithms be used for IR ? You could put distance information for
> junctions and termini in a matrix and use Floyd-Warshall
> algorithm to compute shortest paths among all junction pairs. This
> would take 10^6 entries which should be ok for a modern PC.

I am no expert on graph theory. My method is home-grown, and tailored
for the "shape" of this data-set. Do you have a web reference which
explains F-M, please?

One thing Mr Sanyal is saying is, I could pre-store the shortest routes
between the c610 + c260 = 880 (say)(junctions/terminii), it would take
880 x 880 entries to do so. This is indeed correct, and is one of the
things I had decided to do. The file size could be under 880 x880 x 2
i.e. under 2 Megabytes (2 bytes to store the distance in 10ths of a km
(so up to 6553.5 kms can be stored, more than enough). No space needed
to store station names since the sequence in the table determines this
automatically (ie 883rd entry would be Jn 2 - Jn 3 shortest distance)

Then, to work out distances between stations that are NOT one of the
880, you only need to do 4 look-ups:-
Say B and Y are the two, and B lies between Jn A and Jn C, and Y between
Jn X and Jn Z. So look up A/X, A/Z, C/X, C/Z and add to them A/B+X/Y,
A/B+Y/Z, B/C+X/Y and B/C+Y/Z respectively - and see which is smallest.

Of courrse, generating this look-up table/matrix is the
computer-intensive task.

> >No: of
> >lines Name
>
> >5 KANALUS
>
> Where is KANALUS?

Gujarat, in the vicinity of KHAMBALIYA, LAKHAIBAWAL,
NEW JAMNAGAR, SIKKA and WANSJALIYA.


> >5 RANAGHAT
>
> Should be 4: towards Kalinarayanpur Jn, towards Gede, towards Bangaon
> Jn, and towards Sealdah. From Kalinarayanpur the routes split towards
> Shantipur and towards Krishnanagar City.

My (huge) Railway Map of India (14th edition, Govt. of India
publication) shows the branch occurring between Ranaghat and
Kalinarayanpur, so the (alleged) 5 branches are:-

Ranaghat to:
BANGAON
GEDE
KALINARAYANPUR
KANCHRAPARA/SEALDAH
SHANTIPUR

But I have found earlier mistakes in the Map. Is this definitely wrong?


> Regards to all.
> ths.


Regards to all

L Webber


------------------------------------------------------------------------
------
Get free personalized email at
<A HREF="http://www.pathfindermail.com/member/login.page">http://www.pathfindermail.com/member/login.page</A>

From: Samit Roychoudhury <>

Subject: Re: MR trains

Date: 27 Aug 1999 11:44:04 -0500


dear srinivas

yes i know what you mean but there is a certain degree of confidence
when
you're a riding a trian which is blessed by the MR factor...

sometimes one IS in a hurry to get to one's destination.

cheers
samit

From: lwebber <>

Subject: Re: Turbhe error, Gauges, Hello again!

Date: 27 Aug 1999 12:02:43 -0500


> Hi Larry,
> Welcome back. I checked out both the new CR long-distance and
suburban
> time-tables and Turbhe is not indicated.
> At present, Thane-Turbhe is only used for freight traffic.

Any chance of getting the names of the stations to Turbhe (even though
freight only?


> There is a
> proposal to extend this line beyond Turbhe to meet
> the Vashi-Belapur line near Nerul which will then provide a shorter
route
> between Thane and Panvel (when compared to
> the present one via Diva).

From my data, this *looks* unlikely as Thane-Turbhe (per
<A HREF="http://www.cr-mumbai.com/routemap/divmap.html)">http://www.cr-mumbai.com/routemap/divmap.html)</A> is shown as 54 kms, which
is about the same as Thane-Panvel... As Nerul-Panvel is another 14 kms,
then even if Turbhe-Nerul is a couple of kms, the "shortcut" would
appear to be longer.

Where is the error?


> I will get back to you regarding the gauges.

Please do. My Bradshaws leave these unmarked.

ER Rajgir - Bakhtiyarpur Jn.
NEFR New Bongaigaon - Goalpara Town
WR Jambusar Jn. - Bodeli


> In the meantime, check out the FAQ page at
> <A HREF="http://meltingpot.fortunecity.com/syria/716">http://meltingpot.fortunecity.com/syria/716</A>

Will do!


> We have had numerous discussions on how to classify junctions - this
is in
> the trivia section.
> Vijay

Any suggestions re the electrical problem? :(


Regards

Larry


------------------------------------------------------------------------
------
Get free personalized email at
<A HREF="http://www.pathfindermail.com/member/login.page">http://www.pathfindermail.com/member/login.page</A>

From: lwebber <>

Subject: Re: Shortest Routes

Date: 27 Aug 1999 12:52:55 -0500


> > >On hearing this story, I was struck by the fact that the 1 Satpura
Express
> > >starts from Chanda Fort, and any Madras-Delhi train would have
stopped at
> > >Chandrapur (this was the late fifties). So, someone must have
computed
> > >that Madras-Chanda Fort-Jabalpur was NOT the shortest path. Of
course,
> > >the most "sensible" way of getting to Jabalpur would probably have
been
> > >Madras-Itarsi-Jabalpur.
> >
> > Yes and No (here we ignore how many train/gauge changes are required
-
> > more on that later). Use of EGMORE would add 2 kms to everything (so
it
> > is irrelevant). >
> > CHENNAI CENTRAL - ONGOLE - VIJAYAWADA - BALHARSHAH - WARDHA - NAGPUR
-
> > GONDIA - JABALPUR = 1452 kms
> > is actually the shortest - no Itarsi.
> >
> > The shortest route via Itarsi is much longer - as it too passes
through
> > Nagpur, we just need to compare:-
> > NAGPUR - GONDIA - JABALPUR = 357 kms
> > while
> > NAGPUR - ITARSI - JABALPUR = 543 kms
> > So there is an extra 186 kms via Itarsi, making:
> > CHENNAI CENTRAL - ITARSI - JABALPUR = 1638 kms
> >
> > However
> > CHENNAI CENTRAL - CHANDA FORT - JABALPUR = 1741 kms, another 103 kms
longer still.
>
> Many thanks for your input! My only point with regard to the
> Chennai-Itarsi-Jabalpur route was that it would be the most
"sensible,"
> that is, the most convenient (least number of changes) and probably
the
> fastest as well. I knew very well that it was not be the shortest
> route. Quite obviously, the "shortest" route has nothing to do with
being
> the "fastest."

Sure. When I have a linked TT, both "faster" and "shorter" and EVEN
"most sensible" (this by linking in some conditions re how many changes,
subjective/comfort ratings for lines) could be generated.

> > No, ALL possible ways would take the life of the Universe to
compute,
> > and then more. There are hundreds of "junction points"....
> > The algorithm I have written uses probability and trigonometry (to
> > favor in which direction to head - but remember, sometimes
> > you need to head in the opposite direction too, so the program uses
> > randomness too) and lots of permutations are generated. For
> > all the above, tens of millions of "legs" were considered. The more
time
> > you give it, the more probable you are that the best
> > result found so far is THE best. In practise on a modern PC, for
short
> > distances (under 250 kms) my algorithm generates >99% results
> > (probability the route is distance-optimal) in a second or so. For
about
> > 1,000 kms routes, in 15 seconds or so. For about 2,000 km
> > routes, several minutes. For the really long routes
> > (Likhapani-Kanniyakumari!) it can take several hours to reach near
> > certainty...
> > Of course, it already displays the best answer found so far - it is
just
> > knowing whether that is the BEST possible answer.
>
> Of course, I know that no sensible algorithm can be based on
enumerating
> all possible routes. That was just to mention the "theoretical" way of
> tackling the problem... Incidentally, I'd like to know the
> algorithm you use, if that's okay with you.

Hard to describe. The program "tends" to head in the direction of the
ultimate destination at each leg - but the program uses randomness to
ensure it will eventually try out all possible choices. This way you
get an INSTANT answer (or a few in under a second or so, getting better
and better). There is a method for preventing the same route from being
recomputed and for any route to be re-entrant.


>It's very interesting to note
> that your results show that the PRS
> (Public Reservation System) algorithm can be improved upon. However,
I'd
> still like to know the actual algorithm used by PRS.

Ten old railwaymen with many years experience sitting at a desk
somewhere and receiving the computer requests? ;)


> Just out of curiosity, can your algorithm be modified to get an
> approximate answer to questions of the following sort: How many
distinct
> ways are there for getting from, say, Mumbai to Calcutta? (Please
note
> that I say "approximate" and I ask this because you mention that your
> algorithm uses probability.)

Not in any simple way that I can think of, but I can think of a way to
caluclate this (no doubt it is well-known to theory). But it would not
help with the task of computing the shortest route.

Also - the answer is infinity unless we restrict routes so they are not
re-entrant (i.e., no station is visited more than once in a route), of
course ;)

> Suresh

If there are any routes that interest you, do ask, and I will plug them
into my magic box!


Regards to all

Larry


------------------------------------------------------------------------
------
Get free personalized email at
<A HREF="http://www.pathfindermail.com/member/login.page">http://www.pathfindermail.com/member/login.page</A>

From: T.H.Sanyal. <>

Subject: Re: Shortest Routes, PRS Mistakes..?!

Date: 27 Aug 1999 13:48:00 -0500


Larry Webber said:

>I am no expert on graph theory. My method is home-grown, and tailored
for the
> "shape" of this data-set. Do you have a web reference which explains
F-M,
> please?

I don't have a web reference, but Floyd-Warshall is simple enough.

Notation: Suppose we have N nodes in the network, numbered 1 through N.
Let A(i,j,k) denote the shortest path length from i to j where the
intermediate nodes numbered higher than k are not allowed.

Initially, we define all entries
A(i,j,0) = distance from i to j if they are connected
infinity if i,j not connected

The goal is to compute A(i,j,N) for all i,j pairs; meaning that all the
intermediate stations are allowed to be used.

FOR k := 1 TO N DO
FOR i := 1 TO N DO
FOR j := 1 TO N DO
A(i,j,k) := min (A(i,j,k-1), A(i,k,k-1) + A(k,j,k-1))

Since Layer k calculation depends only on layer k-1, You need to store
only 2 copies of the 880 x 880 matrix.

>Then, to work out distances between stations that are NOT one of the
880, you
> only need to do 4 look-ups:-
>Say B and Y are the two, and B lies between Jn A and Jn C, and Y
between Jn X
> and Jn Z. So look up A/X, A/Z, C/X, C/Z and add to them A/B+X/Y,
A/B+Y/Z,
> B/C+X/Y and B/C+Y/Z respectively - and see which is smallest.

This is exactly what I was thinking.

>Of courrse, generating this look-up table/matrix is the
computer-intensive .
>task

But needs to be done only once.

>> >5 RANAGHAT
>>
>> Should be 4: towards Kalinarayanpur Jn, towards Gede, towards Bangaon
>> Jn, and towards Sealdah. From Kalinarayanpur the routes split towards
>> Shantipur and towards Krishnanagar City.

>My (huge) Railway Map of India (14th edition, Govt. of India
publication)
>shows
> the branch occurring between Ranaghat and Kalinarayanpur, so the
(alleged) 5
> branches are:-

>Ranaghat to:
>BANGAON
>GEDE
>KALINARAYANPUR
>KANCHRAPARA/SEALDAH
>SHANTIPUR

>But I have found earlier mistakes in the Map. Is this definitely
wrong?

Yes. I know that area.

Regards to all.
ths.

From: David Trotter <>

Subject: Unsubscribe!

Date: 27 Aug 1999 14:07:49 -0500


Hi Gang:
 
Regretfully I have to unsubscribe at this point in time as I am going off on holiday to the USA!
I hope to return in late September and will contact you at that time.
 
In the meantime many thanks for the wealth of messages received and which I have enjoyed reading.
 
Best Wishes
 

From: Sundar Krishnamurthy <>

Subject: Turbhe line

Date: 27 Aug 1999 14:50:49 -0500


Hello Larry

Well - the Thane-Turbhe line has no stations or service to speak of as
now... and I was witness to this line being weathered and rusted without

trains. My college was quite close to this line and I can tell you more
about this.

The Thane-Turbhe line runs parallel to the Thane-Belapur road along the
Parsik hill range. It was originally meant for the FCI yard at Turbhe
near
Vashi... and I've seen freight trains on this line only *three* times in
my
four years of college. I think it could emerge as a vital link
connecting
Thane directly with the harbour line from Vashi to Panvel. The Thane
Belapur road is jammed with tons of middle-to-heavy manufacturing
industries and now - even boasts of a Technopark.

This line takes a eastward Y off the CR main line on two sharp curves
after
crossing the Thane Creek before the Parsik tunnel. The probable stations
in
the future on this line are Airoli (a teeming suburb in Navi Mumbai),
Ghansoli, Rabale, MAHAPE (home of the Maharashtra Govt's ambitious
software
Technology park) , Kopar Khairane (Shanti Nagar), Pavane. The line now
ends
into a yard at Turbhe. The line is a single track affair with 1.5 KV DC
electrification. The only engines I've ever seen were WDS4s of Kurla.
The
route is being extended - construction is now on for a Turbhe station
and
the line goes under the Mumbai-Pune highway flyover before joining the
harbour line going towards Juinagar on the Navi Mumbai suburban route.

Talking about the max fan-out junctions.. How about Diva? U can go to
Thane
direct, Mumbra, Panvel, Dombivali and Bhivandi - that makes it five!

In fact the Thane-Kalyan stretch is fascinating for trainspotting at
nights... nothing like seeing the locomotive beam sear through
nothingness
on the uninhabited Diva-Dombivli stretch. Has anyone seen a local train
"FLY" in the night ??? Just park yourself on the stretch before the
Vashi
road creek bridge in Navi Mumbai and have the best time in your life!
There
is no light anywhere except the train on the embankment after the bridge

and the reflection on the still salty waters that sends your adrenaline
sky
high.

Regards

Sundar

From: Karthikeyan Seetharaman <>

Subject: Re: Questions on IR trivia

Date: 27 Aug 1999 14:55:58 -0500


Some trivia questions that I always wanted to know...
Which station has the most number of tracks? Most number of platforms?
And which city has the most number of stations (excluding the metro
trains,
i.e. Madras has 5 : Tambaram, Mambalam, Egmore, Central and Perambur,
considering Tambaram is in madras)
-Karthik

____________________________________________________________________
Get your own FREE, personal Netscape WebMail account today at
<A HREF="http://webmail.netscape.com">http://webmail.netscape.com</A>.

From: lwebber <>

Subject: Re: Shortest Routes, PRS Mistakes..?!

Date: 27 Aug 1999 15:32:21 -0500


> > My method is home-grown, and tailored for the
> > "shape" of this data-set. Do you have a web reference
>
> I don't have a web reference, but Floyd-Warshall is simple enough.
> Notation: Suppose we have N nodes in the network, numbered 1 through
N.
> Let A(i,j,k) denote the shortest path length from i to j where the
> intermediate nodes numbered higher than k are not allowed.
> Initially, we define all entries
> A(i,j,0) = distance from i to j if they are connected
> infinity if i,j not connected
> The goal is to compute A(i,j,N) for all i,j pairs; meaning that all
the
> intermediate stations are allowed to be used.
> FOR k := 1 TO N DO
> FOR i := 1 TO N DO
> FOR j := 1 TO N DO
> A(i,j,k) := min (A(i,j,k-1), A(i,k,k-1) + A(k,j,k-1))
> Since Layer k calculation depends only on layer k-1, You need to store
> only 2 copies of the 880 x 880 matrix.

I wondered if this was what you were referring to as the F-W way...
Yes, you are missing something (your original question) :) I would
have been worried if the math-boffins found something I had missed.

You have just described one of the very first (and elementary) methods I
ever tried when developing this route-optimizing technique - so, please
inform the academic world the title if Floyd-Warshall-WEBBER now... I
thought it probably had been thought of before.... Thanks for telling me
the name ;)

However, it is quite impractical in this application, for the following
reason:

One has to perform SEVEN HUNDRED MILLION loops, each involving an
addition, three subtractions, three indexed table look-ups (so six
multiplications and six additions more), a comparison and an indexed
assignation (so two multiplications and additions more), and then a
number of loop operations (index increment, check if exceeded limit(s)).
This takes quite a while to do... Even in assembly language. And then
, if even ONE item of data changes (even one "amended" distance, one
"new" station, one "incorrect" linkage - see below ;) ), THE WHOLE
THING HAS TO BE TOTALLY RECOMPUTED FROM SCRATCH. THERE IS NO SAFE
SALVAGE IMO (except just in the rare special case that the amendment
relates only to a "spur" - even then, non-trivial).

And in this IR environment, new information KEEPS COMING IN. The
maps/Regional TTs/T-A-A-Gs/Bradshaws/Web/anecdotal sources are often
self- and mutually- contradictory. Every day I find one or more new
error or problem!

My way, I can amend data - and (even for long distance routes) get a 95%
probability "best route" in less than 5 seconds... (less than 0.1
seconds for shorter ones)...


> >Then, to work out distances between stations that are NOT one of the
880, you
> > only need to do 4 look-ups:-
> >Say B and Y are the two, and B lies between Jn A and Jn C, and Y
between Jn X
> > and Jn Z. So look up A/X, A/Z, C/X, C/Z and add to them A/B+X/Y,
A/B+Y/Z,
> > B/C+X/Y and B/C+Y/Z respectively - and see which is smallest.

> This is exactly what I was thinking.

:)

> >Of course, generating this look-up table/matrix is the
computer-intensive
> >task
>
> But needs to be done only once.

If only... see above. :)


> >> >5 RANAGHAT
> >>
> >> Should be 4: towards Kalinarayanpur Jn, towards Gede, towards
Bangaon
> >> Jn, and towards Sealdah. From Kalinarayanpur the routes split
towards
> >> Shantipur and towards Krishnanagar City.
>
> >My (huge) Railway Map of India (14th edition, Govt. of India
publication)
> >shows the branch occurring between Ranaghat and Kalinarayanpur, so
the
> >(alleged) 5 branches are:-
>
> >Ranaghat to:
> >BANGAON
> >GEDE
> >KALINARAYANPUR
> >KANCHRAPARA/SEALDAH
> >SHANTIPUR
>
> >But I have found earlier mistakes in the Map. Is this definitely
wrong?
>
> Yes. I know that area.

And this is exactly an example of the big problem I listed above! ;)


> Regards to all.
> ths.


Regards to all

L Webber


------------------------------------------------------------------------
------
Get free personalized email at
<A HREF="http://www.pathfindermail.com/member/login.page">http://www.pathfindermail.com/member/login.page</A>

From: lwebber <>

Subject: Re: Turbhe line

Date: 27 Aug 1999 15:36:16 -0500


> Hello Larry
> Well - the Thane-Turbhe line has no stations or service to speak of as

> now... and I was witness to this line being weathered and rusted
without
> trains. My college was quite close to this line and I can tell you
more
> about this.
> The Thane-Turbhe line runs parallel to the Thane-Belapur road along
the
> Parsik hill range. It was originally meant for the FCI yard at Turbhe
near
> Vashi... and I've seen freight trains on this line only *three* times
in my
> four years of college. I think it could emerge as a vital link
connecting
> Thane directly with the harbour line from Vashi to Panvel. The Thane
> Belapur road is jammed with tons of middle-to-heavy manufacturing
> industries and now - even boasts of a Technopark.
> This line takes a eastward Y off the CR main line on two sharp curves
after
> crossing the Thane Creek before the Parsik tunnel. The probable
stations in
> the future on this line are Airoli (a teeming suburb in Navi Mumbai),
> Ghansoli, Rabale, MAHAPE (home of the Maharashtra Govt's ambitious
software
> Technology park) , Kopar Khairane (Shanti Nagar), Pavane. The line now
ends
> into a yard at Turbhe. The line is a single track affair with 1.5 KV
DC
> electrification. The only engines I've ever seen were WDS4s of Kurla.
The
> route is being extended - construction is now on for a Turbhe station
and
> the line goes under the Mumbai-Pune highway flyover before joining the

> harbour line going towards Juinagar on the Navi Mumbai suburban route.

Thanks for that clarification. :)


> Talking about the max fan-out junctions.. How about Diva? U can go to
Thane
> direct, Mumbra, Panvel, Dombivali and Bhivandi - that makes it five!

You are right - even six, counting Turbhe (accessed both from Diva and
Thane, part of the track same as the non-Kalva part of Thane-Diva. I
put DIVA to one side until I had more data on Turbhe.

MATHURA still rules, though, with seven! (Until someone shows me
otherwise) :)


> In fact the Thane-Kalyan stretch is fascinating for trainspotting at
> nights... nothing like seeing the locomotive beam sear through
nothingness
> on the uninhabited Diva-Dombivli stretch. Has anyone seen a local
train
> "FLY" in the night ??? Just park yourself on the stretch before the
Vashi
> road creek bridge in Navi Mumbai and have the best time in your life!
There
> is no light anywhere except the train on the embankment after the
bridge
> and the reflection on the still salty waters that sends your
adrenaline sky
> high.

I have similar memories...

But only special for us rail-nuts, 0.01% of the world-population! :)


> Regards
> Sundar

Regards

Larry


------------------------------------------------------------------------
------
Get free personalized email at
<A HREF="http://www.pathfindermail.com/member/login.page">http://www.pathfindermail.com/member/login.page</A>

From: Vdate <>

Subject: Re: MR trains

Date: 27 Aug 1999 16:19:45 -0500


If I was a railway minister, I would pick the trains randomly, every day

From: Vdate <>

Subject: Re: "MR" category

Date: 27 Aug 1999 16:29:17 -0500


Do must run trains have anything to do with the mail carrying status of
the
train. That is, if a train has RMS, it gets priority to run through. by
the
way, do they still have RMS on trains and do they still sort the mail in
it?

From: lwebber <>

Subject: Re: Questions on IR trivia

Date: 27 Aug 1999 17:56:20 -0500


>Some trivia questions that I always wanted to know..
>Which station has the most number of tracks? Most number of platforms?

I would guess New Delhi for both of these... but it is only a guess.
Those overbridges seem very, very long.

Also, how do you define a platform? On NDLS I recall one stretch being
called 2 different platforms on the same side.

B.T.W., does anyone know WHY Kharagpur had such a long platform? Did,
back in the time of the Raj, someone's son own a cement factory nearby?
;)


>And which city has the most number of stations (excluding the metro
trains,
>i.e. Madras has 5 : Tambaram, Mambalam, Egmore, Central and Perambur,
>considering Tambaram is in madras)

Could depend on definition. Mumbai, for example, has regular
long-distance trains that start/terminate from all these stations:-
Mumbai CT, Mumbai CST, Dadar, Kurla and Kalyan (OK, Kalyan is stretching
it, but 38 kms from Kurla...) - but maybe also Mahim/Bandra (this is
from memory - am I correct?).


>-Karthik

I am probably over-posting, sorry. It has been 8 months!


Regards to all

L Webber


------------------------------------------------------------------------
------
Get free personalized email at
<A HREF="http://www.pathfindermail.com/member/login.page">http://www.pathfindermail.com/member/login.page</A>

From: Rajan Mathew <>

Subject: Re: Clarif on Train numbering / Up &Down

Date: 27 Aug 1999 19:16:47 -0500


Gang

I must state that the Lokmanya Tilak (T) (Kurla) - Howrah express
is one of the most pathetic in speed and number of stops.....

But then, I guess, "slow" expresses are a necessary thing on IR, so that
smaller places are linked with main cities ....

Rajan

BTW - I'm off to Chiplun for the weekend ... by the Matsyagandha Exp
this
afternoon ....

----- Original Message -----
From: S.Shankar <shankie@emirates.email
To: Nitin Joshi <npjoshi@attcanada.email
Cc: Samit Roychoudhury <samr@vsnl.email IRFCA <irfca@cs.email
Sent: Thursday, August 26, 1999 8:14 PM
Subject: Re: Clarif on Train numbering / Up &Down


> Hello,
> Other super slow 'express' trains are:
>
> Udyan Abha Toofan Express
> Kurla Howrah Express
> There used to be a super slow Madras-Howrah Express till the early
> 80s,which was scrapped and replaced with the superfast Coromandel.
> Also Saurashtra Janata Express, Bombay-Ferozepore Janata,and so on and
> so forth.
> Cheers. (or is it?)
> Shankar
>
>
>
>
> Nitin Joshi wrote:
> >
> > The illusion of the word Express for short distance trains can be
> > lived with,
> > but when it comes to long distance journeys
> > I would rate the Sabarmati as the most agonising journey.
> >
> > Bye
> > Nitin Joshi
> >
> > ----- Original Message -----
> > From: Samit Roychoudhury
> > To: IRFCA
> > Sent: 25.August.99 15:57
> > Subject: Fw: Clarif on Train numbering / Up &Down
> >
> > what aboutthe yucky howrah - ahmedabad express? lived many a
> > night and day
> > in that...
> >
> > ----- Original Message -----
> > From: S.Shankar <shankie@emirates.email
> > To: <sundar@spyring.email
> > Cc: <irfca@cs.email
> > Sent: Thursday, August 26, 1999 00:29
> > Subject: Re: Clarif on Train numbering / Up &Down
> >
> > > Sundar Krishnamurthy wrote:
> > > >
> > > I rate 6009/6010 Chennai mail as the most leisurely train
> > out of CST.
> > > There
> > > > would be very few main line express trains in India that
> > have a schedule
> > > > speed lower than this one - 43 kmph !
> > > >
> > > > Regards
> > > >
> > > > Sundar
> > >
> > >
> > >
> > >
> > > Hello Sundar,
> > > You think the Madras-Bombay Mail is slow?
> > >
> > > You forget the following trains, which are called
> > expresses, but are in
> > > reality a cruel joke on the poor travellers:
> > >
> > > 1 Dadar-Amritsar Express
> > > 2 Kolhapur-Gondia Maharashtra Express
> > > 3 & 4 Bombay Kolhapur Koyna Express and Sahyadri Express
> > > 5.Ahmedabad-Gorakhpur Sabarmati Express
> > > 6.Bombay Central-Dehradun Express
> > > 7.Narmada Express (from Jabalpur to I forget where)
> > > 8.The now resurrected Howrah-Delhi Janata Express
> > > 7.H.Nizamuddin-Agra Intercity Express
> > > 8.Madras-Jolarpettai Yelagiri Express
> > > 9.Tirupati-Howrah Express
> > > 10.Secunderabad-Guntur Golconda Express
> > > 11.Secenderabad-Sirpur Kagaznagar Bhagyanagar Exp. (OK,
> > its part
> > > passenger)
> > >
> > > There used to be some superslow express trains on the mg
> > in Bihar (in
> > > the Darbhanga-Jogbani belt), and in Gujarat (Girnar
> > Express?)
> > >
> > > Need I name any more?
> > >
> > > Cheers!
> > >
> > > Shankar.
> > > >
> > > > >Hello,
> > > > >Minor correction:
> > > > >It was not Dadar-Chennai Express in its earlier days,
> > > > >but Dadar-Madras Chennai Express.
> > > > >It was so named to eliminate confusion among the
> > passengers
> > > > >due to the existance of two Dadar-Madras Express trains
> > on the
> > > > >route, though people still preferred to refer to the
> > Chennai
> > > > >Express as 'Madras superfast'
> > > > >long after it was de-rated.
> > > > >Cheers.
> > > > >Shankar
> > >

The content of the individual messages displayed here is subject to copyright by the original authors and may not be reproduced outside the context of IRFCA without permission.
Note: This site is not officially affiliated with Indian Railways! The official web site of Indian Railways is: http://www.indianrailways.gov.in
Site contact: webmaster@irfca.org
Copyright © 2010, IRFCA.org. About IRFCA  Contact Us  Search this site  Site Map  Links   Acknowledgements  Legal Information & Disclaimers