Let’s suppose you’re going from Reading to Hanwell. You might have to
make as many as 2 changes (at Slough, and Hayes & Harlington), to reach
a station you’d simply pass through if you didn’t change. What’s the
most such changes a (sensible & perfectly informed) passenger ever has
to make?
--
Ian â—Ž

Ian Clifton wrote:
Let’s suppose you’re going from Reading to Hanwell. You might have to
make as many as 2 changes (at Slough, and Hayes & Harlington), to reach
a station you’d simply pass through if you didn’t change. What’s the
most such changes a (sensible & perfectly informed) passenger ever has
to make?

I assume doubling back isn't allowed, otherwise you could do that in one
(changing at Paddington)?

Travelling on a Sunday in the winter, try Bourg St Maurice to Stratford
International. I make 5 changes:

Bourg St Maurice - Moutiers-Salins-Bride-les-Bains - Paris Gare de Lyon -
Chatelet les Halles - Paris Gare du Nord - Ashford/Ebbsfleet International -
Stratford International

(on weekdays the ski train stops at Ashford. I don't know if there are
direct trains from Moutiers to Lille in the winter which would cut the
changes to 3)

Theo

In reply to this post from Theo to on 28 Mar 2019 at 16:52 ...

Ian Clifton wrote:
Let’s suppose you’re going from Reading to Hanwell. You might have to
make as many as 2 changes (at Slough, and Hayes & Harlington), to reach
a station you’d simply pass through if you didn’t change. What’s the
most such changes a (sensible & perfectly informed) passenger ever has
to make?

I assume doubling back isn't allowed, otherwise you could do that in one
(changing at Paddington)?

Travelling on a Sunday in the winter, try Bourg St Maurice to Stratford
International. I make 5 changes:

Bourg St Maurice - Moutiers-Salins-Bride-les-Bains - Paris Gare de Lyon -
Chatelet les Halles - Paris Gare du Nord - Ashford/Ebbsfleet International -
Stratford International

(on weekdays the ski train stops at Ashford. I don't know if there are
direct trains from Moutiers to Lille in the winter which would cut the
changes to 3)

Theo

A "sensible & perfectly informed passenger" would know that you can get from Gare de Lyon to Gare du Nord by RER D without the need to change at Châtelet-Les-Halles.
--
Richard J.
(to email me, swap 'uk' and 'yon' in address)

"Richard J." writes:

In reply to this post from Theo to
on 28 Mar 2019 at 16:52 ...

Ian Clifton wrote:
Let’s suppose you’re going from Reading to Hanwell. You might have to
make as many as 2 changes (at Slough, and Hayes & Harlington), to reach
a station you’d simply pass through if you didn’t change. What’s the
most such changes a (sensible & perfectly informed) passenger ever has
to make?

I assume doubling back isn't allowed, otherwise you could do that in one
(changing at Paddington)?

Travelling on a Sunday in the winter, try Bourg St Maurice to Stratford
International. I make 5 changes:

Bourg St Maurice - Moutiers-Salins-Bride-les-Bains - Paris Gare de Lyon -
Chatelet les Halles - Paris Gare du Nord - Ashford/Ebbsfleet International -
Stratford International

(on weekdays the ski train stops at Ashford. I don't know if there are
direct trains from Moutiers to Lille in the winter which would cut the
changes to 3)

Theo

A "sensible & perfectly informed passenger" would know that you can
get from Gare de Lyon to Gare du Nord by RER D without the need to
change at Châtelet-Les-Halles.

I think I intended something like Theo’s solution to be valid. But
you’re right, in that calling my Passenger “sensible� is inadequate and
probably misleading. A sensible person would probably make a longer or
more expensive journey, rather than endure the faff of many
changes. Maybe it’s better to make him an automaton: the Passenger
always boards the very next train that gets him at all closer to the
destination (even if a following train would get him closer still, or
would reduce the subsequent changes required).
--
Ian â—Ž

On 29/03/2019 00:48, Richard J. wrote:
In reply to this post from Theo to
onÂ* 28 Mar 2019 at 16:52 ...

Travelling on a Sunday in the winter, try Bourg St Maurice to Stratford
International. I make 5 changes:

Bourg St Maurice - Moutiers-Salins-Bride-les-Bains - Paris Gare de Lyon -
Chatelet les Halles - Paris Gare du Nord - Ashford/Ebbsfleet
International -
Stratford International

(on weekdays the ski train stops at Ashford.Â* I don't know if there are
direct trains from Moutiers to Lille in the winter which would cut the
changes to 3)

Theo

A "sensible & perfectly informed passenger" would know that you can get
from Gare de Lyon to Gare du Nord by RER D without the need to change at
Châtelet-Les-Halles.

I read the original post as applying to journeys on a single line, not
one where you change lines on the way.

So if the only train you can catch at your local station doesn't stop
where you want to get to, but there is a station where both trains stop,
you have to change trains.

As such, you should never need to change trains on the Underground short
of a service problem on the District, Circle and Hammersmith and City
lines, where they occasional change a Circle line train to H&S, stopping
short. (Probably not the only place it can happen, but it caught me out
recently, and ignoring the length where the Picadilly and District
lines run on parallel tracks, but share some stations. I count those as
different lines.)

--
Tciao for Now!

John.

Ian Clifton wrote:
"Richard J." writes:
A "sensible & perfectly informed passenger" would know that you can
get from Gare de Lyon to Gare du Nord by RER D without the need to
change at Châtelet-Les-Halles.

Apologies, I think I misremembered a change.
(Also, I have a feeling there are through trains from Bourg to northern
FR/BE/NL in the winter, which might skew things somewhat)

I think I intended something like Theo’s solution to be valid. But
you’re right, in that calling my Passenger “sensible� is inadequate and
probably misleading. A sensible person would probably make a longer or
more expensive journey, rather than endure the faff of many
changes. Maybe it’s better to make him an automaton: the Passenger
always boards the very next train that gets him at all closer to the
destination (even if a following train would get him closer still, or
would reduce the subsequent changes required).

That would make it quite sensitive to time of day and service pattern, which
would make the challenge rather fragile.

Freedom to pick any train on a given day might make sense - the traveller
can start at 00.01 and take any combination of trains that gets them there
by closedown the next morning. But they can't wait for the one through
train a week. Or you could look at trains with a regular service pattern -
perhaps the last train is an all-stations stopper, but during the daytime
you'd have to change.

The next question is whether the passenger must travel on the same line as
the through train, or whether they can take an alternative route (in my
example, you'd probably have to use the around-Paris HSL rather than going
into Gare de Lyon). I'd suggest the station should be one passed through by
the through train, but they passenger need not take the same route to get
there. (So for Inverness to Finsbury Park the traveller could
change at Stevenage and take the Hertford Loop).

Theo

John Williamson writes:

On 29/03/2019 00:48, Richard J. wrote:
In reply to this post from Theo
to onÂ* 28 Mar 2019 at 16:52 ...

Travelling on a Sunday in the winter, try Bourg St Maurice to Stratford
International. I make 5 changes:

Bourg St Maurice - Moutiers-Salins-Bride-les-Bains - Paris Gare de Lyon -
Chatelet les Halles - Paris Gare du Nord - Ashford/Ebbsfleet
International -
Stratford International

(on weekdays the ski train stops at Ashford.Â* I don't know if there are
direct trains from Moutiers to Lille in the winter which would cut the
changes to 3)

Theo

A "sensible & perfectly informed passenger" would know that you can
get from Gare de Lyon to Gare du Nord by RER D without the need to
change at Châtelet-Les-Halles.

I read the original post as applying to journeys on a single line, not
one where you change lines on the way.

Yes, that’s what I meant, at first. This all came from a genuine journey
I was planning (Oxford to Hanwell), I came up with the two�change
journey myself and then decided to see what Network Rail’s Journey
Planner made of it. I thought the Journey Planner would always come up
with a boring but “sensible� one change plan, and was slightly surprised
when it came up with the double change plan too (only for certain
departure times, of course). I then began to wonder if a higher number
of changes could ever be required, and thought this might happen where
several different services (partly) share the same route. But I’m
struggling to make the conditions of the puzzle really concrete.

[...]

--
Ian â—Ž

In message , at 16:48:32 on Fri, 29 Mar
2019, Ian Clifton remarked:

I’m struggling to make the conditions of the puzzle really concrete.

I'm tempted to say "don't you just love it when civilians try to be
policy wonks".

But the question as posed was almost tightly enough drawn nevertheless.

My own reservations were only about whether doubling back (thus
requiring perhaps specialised ticketing) was allowed as part of the
challenge, as well as enforced overnight - or even longer - layovers.

For example, Denton to Reddish South, which until recently took a week
with two double-backs, if we stick to the "on the same line" rule.
--
Roland Perry

On Fri, 29 Mar 2019 16:48:32 +0000, Ian Clifton
wrote:

John Williamson writes:

On 29/03/2019 00:48, Richard J. wrote:
In reply to this post from Theo
to on* 28 Mar 2019 at 16:52 ...

Travelling on a Sunday in the winter, try Bourg St Maurice to Stratford
International. I make 5 changes:

Bourg St Maurice - Moutiers-Salins-Bride-les-Bains - Paris Gare de Lyon -
Chatelet les Halles - Paris Gare du Nord - Ashford/Ebbsfleet
International -
Stratford International

(on weekdays the ski train stops at Ashford.* I don't know if there are
direct trains from Moutiers to Lille in the winter which would cut the
changes to 3)

Theo

A "sensible & perfectly informed passenger" would know that you can
get from Gare de Lyon to Gare du Nord by RER D without the need to
change at Châtelet-Les-Halles.

I read the original post as applying to journeys on a single line, not
one where you change lines on the way.

Yes, that’s what I meant, at first. This all came from a genuine journey
I was planning (Oxford to Hanwell), I came up with the two?change
journey myself and then decided to see what Network Rail’s Journey
Planner made of it. I thought the Journey Planner would always come up
with a boring but “sensible” one change plan, and was slightly surprised
when it came up with the double change plan too (only for certain
departure times, of course). I then began to wonder if a higher number
of changes could ever be required, and thought this might happen where
several different services (partly) share the same route. But I’m
struggling to make the conditions of the puzzle really concrete.

[...]
I had a look at my line, the Chiltern. Possible journey Brum Moor
Street to one of the stations between South Ruislip and Wembley. The
timetable sites insisted that I go beyond my destination and double
back at either Wembley or Marylebone. I decided I could not be
bothered to look up detail timetables - sorry to be so idle.

Guy Gorton

On 30/03/2019 12:51, Guy Gorton wrote:

I had a look at my line, the Chiltern. Possible journey Brum Moor
Street to one of the stations between South Ruislip and Wembley. The
timetable sites insisted that I go beyond my destination and double
back at either Wembley or Marylebone. I decided I could not be
bothered to look up detail timetables - sorry to be so idle.

So the timetable sites refuse to give the cheapest route... not good!

--
Basil Jet - Current favourite song...
Spratleys Japs - Hands (Marc Riley session)
https://www.youtube.com/watch?v=PTFmVrE1WAc