Richard Dixon wrote:

Dear All

I hope I've come to the right place to ask this question.

I was commenting with a colleague recently how she (living in Sevenoaks)
takes a similar amount of time as me (in Raynes Park) to get into work
(we're based in Monument).

It made me wonder if anyone has re-designed a London travel map in terms of
time frame of reference - i.e. shortest time taken to get to a major London
station (e.g. Waterloo, Victoria, London Bridge, Liverpool Street etc.)
from around the south-east?

Just interested from a commuting viewpoint.

I've seen such a map, but I can't remember exactly where, though it may
have been North Greenwich station. There were two versions: one showing
the situation before the Jubilee was extended, and one after.

"Dave Arquati" wrote in message

[snip]

There is software available to companies involved in transport
planning
which can plot "isochrones" (contours of time) of public transport
journey time to a specific point in London.

Unfortunately I can't immediately see any available on the
internet.

When I joined my last company in 1988 the personnel dept had a
printed map for London's public transport, mostly oriented to trains
coming in from outer suburbia, as I recall. The map was ancient
then, disintegrating, and held together with sellotape. I don't
remember who published it. As a child, I remember seeing pre WW II
atlases, old then, with maps of Britain, coloured like contour maps,
showing time to reach London by train.

I think the newer versions of Autoroute do isochrones for cars, and,
of
course, bikes.

There's something funny, though, about the numbers Autoroute produces
if you send it out on a bike at 10 mph.

Every now and again I see "accessibility maps" put out by London's
planning or transport people. I think they credit it to a program
they have called PTAL, or some such. I wonder if you could demand a
copy of the program under the Freedom of Information Act.

Jeremy Parker

Aidan Stanger wrote:
Richard Dixon wrote:


Dear All

I hope I've come to the right place to ask this question.

I was commenting with a colleague recently how she (living in Sevenoaks)
takes a similar amount of time as me (in Raynes Park) to get into work
(we're based in Monument).

It made me wonder if anyone has re-designed a London travel map in terms of
time frame of reference - i.e. shortest time taken to get to a major London
station (e.g. Waterloo, Victoria, London Bridge, Liverpool Street etc.)
from around the south-east?

Just interested from a commuting viewpoint.


I've seen such a map, but I can't remember exactly where, though it may
have been North Greenwich station. There were two versions: one showing
the situation before the Jubilee was extended, and one after.

I remember there used to be a computer terminal in the London Transport
Museum which showed you the Tube map versus a geographical one and an
isochronal one. The isochronal one didn't actually show the lines
though; it just showed points for the major centres like Harrow.

--
Dave Arquati
Imperial College, SW7
www.alwaystouchout.com - Transport projects in London

Jeremy Parker wrote:
"Dave Arquati" wrote in message

[snip]

There is software available to companies involved in transport

planning

which can plot "isochrones" (contours of time) of public transport
journey time to a specific point in London.

Unfortunately I can't immediately see any available on the

internet.

When I joined my last company in 1988 the personnel dept had a
printed map for London's public transport, mostly oriented to trains
coming in from outer suburbia, as I recall. The map was ancient
then, disintegrating, and held together with sellotape. I don't
remember who published it. As a child, I remember seeing pre WW II
atlases, old then, with maps of Britain, coloured like contour maps,
showing time to reach London by train.

I think the newer versions of Autoroute do isochrones for cars, and,
of
course, bikes.

There's something funny, though, about the numbers Autoroute produces
if you send it out on a bike at 10 mph.

Every now and again I see "accessibility maps" put out by London's
planning or transport people. I think they credit it to a program
they have called PTAL, or some such. I wonder if you could demand a
copy of the program under the Freedom of Information Act.

PTAL is a scoring system from 1 (or perhaps zero?) to 6, with 6 being
the highest level of public transport accessibility. The southern
portion of the King's Cross development (developers: Argent) has a PTAL
score of 6, as by the time it is built, it will probably have the best
public transport accessibility in the entire country.

--
Dave Arquati
Imperial College, SW7
www.alwaystouchout.com - Transport projects in London

Stephen Osborn wrote:
John Rowland wrote:
"Stephen Osborn" wrote in message
...

However the contours on an OS map (and AFAIK isobars on a weather
chart)
never touch let alone cross.

They can touch, but they can't cross.

I think you are wrong there.

Contours mark places of equal height. If two contours touch at any
one
point then, de definito, they have to touch at *all* points, so the
two
contours become one contour.

This is a correct argument that two contours _indicating the same
height_ must be coincident if they have at least one point in common;
however consider contours marking _different_ heights; these can
coincide on a non-empty set of points (eg along a vertical cliff)
without necessarily coinciding everywhere.

--
Larry Lard
Replies to group please

Larry Lard wrote:
Stephen Osborn wrote:

John Rowland wrote:

"Stephen Osborn" wrote in message
...


However the contours on an OS map (and AFAIK isobars on a weather

chart)

never touch let alone cross.

They can touch, but they can't cross.

I think you are wrong there.

Contours mark places of equal height. If two contours touch at any

one

point then, de definito, they have to touch at *all* points, so the

two

contours become one contour.


This is a correct argument that two contours _indicating the same
height_ must be coincident if they have at least one point in common;
however consider contours marking _different_ heights; these can
coincide on a non-empty set of points (eg along a vertical cliff)
without necessarily coinciding everywhere.
--

That is true for a _literally_ vertical cliff, which does not actually
occur in nature.

Can you think of any other case that would be true (should "eg along a
vertical cliff" actually have been "ie along a vertical cliff")?


Also I still believe that, to make an accurate time map without
rearranging the order of stations on each line, the isochrones would
have to cross not just touch.


regards

Stephen

On Tue, 22 Feb 2005, Stephen Osborn wrote:

Larry Lard wrote:
Stephen Osborn wrote:

John Rowland wrote:

"Stephen Osborn" wrote in message
...

However the contours on an OS map (and AFAIK isobars on a weather
chart) never touch let alone cross.

They can touch, but they can't cross.

Contours mark places of equal height. If two contours touch at any
one point then, de definito, they have to touch at *all* points, so
the two contours become one contour.

This is a correct argument that two contours _indicating the same
height_ must be coincident if they have at least one point in common;
however consider contours marking _different_ heights; these can
coincide on a non-empty set of points (eg along a vertical cliff)
without necessarily coinciding everywhere.

That is true for a _literally_ vertical cliff, which does not actually
occur in nature.

It might happen that there are no perfectly vertical cliffs, but i don't
think it's impossible in principle, so that doesn't matter.

Also, you do get cliffs like this:

---------/
/
cliff /
/
/
/
/-------
| sea
|

Which are a bit of a problem, as the altitude is discontinuous as you go
from left to right - it goes from X feet in the air to zero without there
being any intervening points.

tom

PS It's best not to put a "-- " before your reply; well-brought-up news
software will trim everything below that from a reply.

--
Destroy - kill all hippies.

"Larry Lard" wrote in message
oups.com...
Stephen Osborn wrote:
John Rowland wrote:
"Stephen Osborn" wrote in message
...

However the contours on an OS map
(and AFAIK isobars on a weather chart)
never touch let alone cross.

They can touch, but they can't cross.

I think you are wrong there.

Contours mark places of equal height. If two contours
touch at any one point then, de definito, they have to
touch at *all* points, so the two
contours become one contour.

This is a correct argument that two contours
_indicating the same height_ must be coincident
if they have at least one point in common;

No. There are many "saddle" points in the landscape where, say, the land is
lower to the north and south, and higher to the east and west. The contour
which marks the height of the saddle point runs away from the saddle point
in 4 directions. It would be perverse to describe the contour as crossing
itself, but the contour could meaningfully be described as touching itself
at this one point. This is as true for a map of isochrones or isobars.

--
John Rowland - Spamtrapped
Transport Plans for the London Area, updated 2001
http://www.geocities.com/Athens/Acro...69/tpftla.html
A man's vehicle is a symbol of his manhood.
That's why my vehicle's the Piccadilly Line -
It's the size of a county and it comes every two and a half minutes

John Rowland wrote:
"Larry Lard" wrote in message
oups.com...
Stephen Osborn wrote:
John Rowland wrote:
"Stephen Osborn" wrote in
message
...

However the contours on an OS map
(and AFAIK isobars on a weather chart)
never touch let alone cross.

They can touch, but they can't cross.

I think you are wrong there.

Contours mark places of equal height. If two contours
touch at any one point then, de definito, they have to
touch at *all* points, so the two
contours become one contour.

This is a correct argument that two contours
_indicating the same height_ must be coincident
if they have at least one point in common;

No. There are many "saddle" points in the landscape where, say, the
land is
lower to the north and south, and higher to the east and west. The
contour
which marks the height of the saddle point runs away from the saddle
point
in 4 directions. It would be perverse to describe the contour as
crossing
itself, but the contour could meaningfully be described as touching
itself
at this one point. This is as true for a map of isochrones or
isobars.

Like this, yes? :

[fixed width font needed]
numbers are heights

0 -1 -2 -3 -2 -1 0
1 0 -1 -2 -1 0 1
2 1 0 -1 0 1 2
3 2 1 0 1 2 3
2 1 0 -1 0 1 2
1 0 -1 -2 -1 0 1
0 -1 -2 -3 -2 -1 0

Surely in this situation there is only one contour, though, and it is
X-shaped. If you want to argue that there are two contours meeting in
the middle, how do you decide whether it's a meeting a , or a ^
meeting a v ?

Anyway, I'm not really sure this branch of this thread (?) has anything
useful to say about the original problem, as raised by Michael Dolbear:
"I think it can't be done on a flat map without rearranging the order
of
stations on each line."


--
Larry Lard
Replies to group please

"Larry Lard" wrote in message
ups.com...

John Rowland wrote:
"Larry Lard" wrote in message
oups.com...

There are many "saddle" points in the landscape where,
say, the land is lower to the north and south, and higher
to the east and west. The contour which marks the height
of the saddle point runs away from the saddle point
in 4 directions. It would be perverse to describe the
contour as crossing itself, but the contour could
meaningfully be described as touching itself
at this one point. This is as true for a map of
isochrones or isobars.

Like this, yes? :

[fixed width font needed]
numbers are heights

0 -1 -2 -3 -2 -1 0
1 0 -1 -2 -1 0 1
2 1 0 -1 0 1 2
3 2 1 0 1 2 3
2 1 0 -1 0 1 2
1 0 -1 -2 -1 0 1
0 -1 -2 -3 -2 -1 0

Surely in this situation there is only one contour, though, and it is
X-shaped. If you want to argue that there are two contours meeting in
the middle, how do you decide whether it's a meeting a , or a ^
meeting a v ?

It's a ^ meeting a v. Look at the bigger picture, which would be like
this...

-------
--0-0--
-0+0+0-
--0-0--
-------

Anyway, I'm not really sure this branch of this thread (?) has anything
useful to say about the original problem, as raised by Michael Dolbear:
"I think it can't be done on a flat map without rearranging the order
of stations on each line."

His statement is so clearly wrong it's hard to argue with it until someone
explains why they think it's right. Every public point in the 2D space has a
scalar quantity associated with it, namely journey time from point X.
Mathematically this is identical to the contour maps, where every point
which is not inside a building has a scalar quantity associated with it,
namely height above sea level.

--
John Rowland - Spamtrapped
Transport Plans for the London Area, updated 2001
http://www.geocities.com/Athens/Acro...69/tpftla.html
A man's vehicle is a symbol of his manhood.
That's why my vehicle's the Piccadilly Line -
It's the size of a county and it comes every two and a half minutes