On Jan 25, 2:50 pm, Tom Anderson wrote:
On Fri, 25 Jan 2008, wrote:
Presumably for trains with few stops the power consumption is
approximately constant regardless of the length of the train because
the main loss will be air drag.

As long as the train never wants to climb a hill, perhaps. If it does, the
old mgh term rears its head.

And you get it back again on the downhills. If we assume a 1000kg car
takes 10kW to maintain 25m/s (about 50mph) on the flat. On a 1 in 50
it will take 15kW to maintain that speed uphill but only 5kW to
maintain that speed downhill. As the speed is constant the time is the
same up and down so the total energy is the average, i.e. same as on
the flat over the same distance.

It's only if you are power limited on the climbs and descend faster
that you lose out because your power requirements go up as cube of
speed to overcome airdrag. This is typically the case for cyclists -
going uphill the speed is low enough that airdrag is negligible and
all the energy goes in mgh. A cyclist coasting down a 1 in 10 at 20m/s
will be using 2kW to overcome the airdrag.

(You also lose out if you have to use braking on the descent and it's
non-regenerative. On a tandem where the power doubles but the drag is
roughly the same the terminal velocity will be about 25% higher and
the tandem will have to dissipate 2kW via the brakes to keep the speed
at 20m/s - which is why tandems often have a hub brake as well as rim
brakes or, nowadays, disk brakes)

Do you think that drag is overwhelmingly greater than rolling resistance,
losses in the bearings, etc?

I'm not sure quite how many orders of magnitude it will differ by but
yes. Beyond any doubt air drag dominates everything else at any sort
of reasonable speed.

Power to overcome airdrag goes up as cube of speed. Friction losses
are linear.

Tim.

"Mizter T" wrote in message
...

And just to prove that things can change for the better, the
"Transfare" ticket scheme has recently been simplified - these are
tickets that allow for through journeys from bus to Metro or vice-
versa. However, perhaps just so as to ensure things don't get too
simple the new Transfare scheme has introduced the new idea of
concentric yellow, green, and grey zones - thankfully these do
actually correspond with the Metro's concentric A, B and C zones, and
they also share the same colours except for Metro zone C being a shade
of violet whilst the outer Transfare zone is grey. I suppose the logic
is that the Transfare grey zone covers much more ground than the Metro
C zone.

Anyhow, here is a page on the new Transfare ticket scheme...
http://www.nexus.org.uk/wps/wcm/conn...etro+Transfare

...and this leaflet shows the new Transfare yellow/green/grey zones
(PDF)...
http://www.nexus.org.uk/wps/wcm/reso...fare%20map.pdf

The world is complicated!

But it was definitely worth pointing out, if only to demonstrate how easy it
will be to program a national Oyster payg...

Paul S

On 25 Jan, 16:31, "Paul Scott" wrote:
"Mizter T" wrote in message

(snip)

And just to prove that things can change for the better, the
"Transfare" ticket scheme has recently been simplified - these are
tickets that allow for through journeys from bus to Metro or vice-
versa. However, perhaps just so as to ensure things don't get too
simple the new Transfare scheme has introduced the new idea of
concentric yellow, green, and grey zones - thankfully these do
actually correspond with the Metro's concentric A, B and C zones, and
they also share the same colours except for Metro zone C being a shade
of violet whilst the outer Transfare zone is grey. I suppose the logic
is that the Transfare grey zone covers much more ground than the Metro
C zone.

Anyhow, here is a page on the new Transfare ticket scheme...
http://www.nexus.org.uk/wps/wcm/conn...es+and+tickets...

...and this leaflet shows the new Transfare yellow/green/grey zones
(PDF)...
http://www.nexus.org.uk/wps/wcm/reso...e4fbc9c/Transf...

The world is complicated!

But it was definitely worth pointing out, if only to demonstrate how easy it
will be to program a national Oyster payg...

Paul S


Perhaps my sarcasm detector isn't working, but I'll take your comment
at face value!

One issue with implementing this Transfare scheme with some kind of
smartcard PAYG system would be the fact that neither bus fares nor
Transfares are flat-rate - look at the leaflet's example of a journey
where a passenger transfers from the Metro at Pelaw in the green zone
and then takes a bus to Washington in the grey zone. The passenger
would have to actively inform the driver of their final destination,
and the driver would have to enter this into their ticket machine and
then have the passenger scan the smartcard so as to ensure the correct
fare was debited. The only other way of doing it would be to implement
a touch-in and touch-out system on buses, which I think would be
totally unworkable.

In fact this has prompted me to start a new thread on utl to ask about
whether Oyster could theoretically support a distance based, non-flat
fare system - the thread is called "Oyster PAYG and differential bus
fares".

On Fri, 25 Jan 2008, wrote:

On Jan 25, 2:50 pm, Tom Anderson wrote:
On Fri, 25 Jan 2008, wrote:
Presumably for trains with few stops the power consumption is
approximately constant regardless of the length of the train because
the main loss will be air drag.

As long as the train never wants to climb a hill, perhaps. If it does, the
old mgh term rears its head.

And you get it back again on the downhills. If we assume a 1000kg car
takes 10kW to maintain 25m/s (about 50mph) on the flat. On a 1 in 50 it
will take 15kW to maintain that speed uphill but only 5kW to maintain
that speed downhill. As the speed is constant the time is the same up
and down so the total energy is the average, i.e. same as on the flat
over the same distance.

Good point. Although speed could only be constant if you had a 15 kW
engine, which would mean you were using less than full power (and i'm not
talking transient overload, since the hills could be long) on the flats.
And that you didn't combine motor and gravity power to go downhill
super-fast. Still, your point stands - you get the energy back.

(You also lose out if you have to use braking on the descent and it's
non-regenerative.

Yes.

tom

--
Memes don't exist. Tell your friends.

On Fri, 25 Jan 2008 14:45:20 +0000, Tom Anderson
wrote:

On Thu, 24 Jan 2008, Mizter T wrote:


This is how things are done in Tyne & Wear - see:

http://www.nexus.org.uk/ufs/shared/i...ne_Map_Col.pdf

The numbering logic behind the zones seems bizarre at first sight -
the zone numbers ascend in a sort of diagonal sweep from the south
west to the north east of the metropolitan county of T&W.

I can understand why you say that but I got used to it quickly - zones
17 and 26 covered my regular journeys!

Surely north west to south east? Oh, you mean like a raster? Yes, i see -
the lines of the raster run SW-NE, and the raster progresses NW-SE.

The diagonal is basically the axis parallel to the Tyne, isn't it? At
least, the downstream reach. It's akin to Stanford's 'logical north'.

Not seen it described like that before but you've made me go back and
look at it afresh.

However I think it may be designed this was to make it easy to issue and
- crucially - verify the validity of tickets with zonal combinations
that are in a row or in a ring (think of a busy bus driver checking
tickets).

I remember picking up the original leaflet for the zonal system before
it was brought into use and being very confused by it. I'd never seen
anything like it and yet it's simple when compared to some German fares
systems.

It settled down very quickly and the ease and simplicity of the
Travelcard ticket was massively popular. It was certainly one aspect of
the Tyne and Wear system that encouraged people to use public transport.
Fares were cheap but the Travelcard - in both peak and off peak versions
- offered very good value for money.

Now it's undermined by everyone - including the Metro - having their own
bewildering range of own operator tickets. The "updated" Transfare
scheme is another mess - another zonal system imposed on top of another
one. Dreadful and indicative of the worst aspects of deregulated
practice.

39. I wonder which zones it counts as being adjacent to? Any which have
piers, i suppose.

Although the zone is very long the sole remaining ferry service runs
between North Shields and South Shields. Therefore the valid and logical
adjacent zones are zones 29 and 38. There is a bus link to the pier at
North Shields as there is a very steep hill up to the town centre and
Metro station. There's little height differential on the South side and
a short walk up a ramp and some stairs brings you to the Market Place
where many buses leave from and 5 minutes further on is the Metro
station.

The only other ferry I recall being in a local timetable book was from
Wallsend to Hebburn and was timed for the shipyard shifts. It was never
in the Travelcard scheme although zone 39 would cover it.

The '4 zones in a ring' option is described as 'any 3 zones in a ring plus
one adjacent zone'; does that mean i could have three in a ring and one
touching just one of them? 56, 58, 59 and 60, say?

As a former Tyne and Wear resident and extensive user of Metro, the
original Transfare scheme and regular Travelcard purchaser then yes that
combination is perfectly valid.
--
Paul C

On Fri, 25 Jan 2008 02:53:24 -0800 (PST), Andy
wrote:

I certainly agree about the lengths of trains on Sundays. I thought
(although I'm not absolutely sure) that PIXC (Passengers In eXcess of
Capacity) standards were supposed to be met all the time. I.E. on
Sundays as well as during the week. Sunday afternoon / evening seem to
be far more crowded than most of the peak trains (except the 19.04!!)
and like you say, it is not difficult to make all the trains 8 cars.

I can't help but wonder if Sundays is a case of "take whatever is next
in the line on the depot when you get there" for the drivers, with no
coupling or uncoupling taking place, as it isn't unknown for one of
the 4 diagrams (usually the wrong one) to be 8-car. Really, with only
4 diagrams, even if (as I suspect due to the lack of Desiros) Sundays
are Bletchley only, with Northampton depot not in use, 8 car on
everything is both practical and necessary.

Neil

--
Neil Williams
Put my first name before the at to reply.

On Fri, 25 Jan 2008 14:29:24 +0000, Tom Anderson
wrote:

Do these trains use the same tracks? If so, isn't that pattern of
departures necessary so the fasts have a clear run ahead of them behind
the preceding slow?

No. The fasts leave Euston on the fast lines and don't cross to the
slows until Ledburn (I think) while the slows leave on the slow lines
and remain there throughout. I think the timings are purely to fit in
between the VTs, which might be the reason for the forthcoming changes
given the total recast of VT's timetable.

You could make 12-car trains, and lock the rear 4 cars OOU on the
southbound leg. You could even unlock them once you were past Bletchley
and into 12-car land (if that's possible, and if it is indeed all
12-car-clear south of there).

Is there a feasible way of locking 4 cars out of use on 321
formations, without having to open the above-door panels and lock each
door out manually? The reason I ask is that there is an element of
that takes place on the 0735ish which starts from Bletchley (with the
rear 4 off the platform but unlocked, such that you can't get to
them), and it seems surprising that they wouldn't think of it. That
said, you don't see 12 cars on any of the Tring slows, and they
probably load the heaviest - is there another short platform, e.g.
Apsley/Kings Langley?

I will be interested to find out if the new Desiros have SDO, as SWT's
ones certainly appear to have some form of it to allow calling at
short platforms on the Waterloo-Reading run. This might allow a
recast fitting with the likely demand (i.e. removing the Leighton
Buzzard stop from the fasts and inserting it into the slows[1] (then
making both 12-car) which is where it was before the last recast when
12-car operation started).

[1] The 1824 does not stop at Leighton Buzzard or Berkhamsted, which I
always suspected to be a crowd control measure given that the xx24 and
xx54 of other hours does.

Neil

--
Neil Williams
Put my first name before the at to reply.

On Fri, 25 Jan 2008 10:27:14 -0800 (PST), Mizter T
wrote:

One issue with implementing this Transfare scheme with some kind of
smartcard PAYG system would be the fact that neither bus fares nor
Transfares are flat-rate - look at the leaflet's example of a journey
where a passenger transfers from the Metro at Pelaw in the green zone
and then takes a bus to Washington in the grey zone. The passenger
would have to actively inform the driver of their final destination,
and the driver would have to enter this into their ticket machine and
then have the passenger scan the smartcard so as to ensure the correct
fare was debited. The only other way of doing it would be to implement
a touch-in and touch-out system on buses, which I think would be
totally unworkable.

It is entirely workable in Singapore (yes, I know, different culture,
but still...). If the method of operation was to charge the maximum
fare for that bus on touch-in and refund the difference on touch-out,
people would soon be motivated to touch in and out correctly, just as
they seem to manage on, say, the DLR, and the Dutch are to introduce
it with their system (which is, notably, going away from zones and
towards market fares).

It would need to be made obvious to start with, but that could be done
by having, say, a green reader on the ticket machine for touch-in and
a red one on the left hand side of the doors for touch-out. Indeed,
it'd be simpler and more consistent than the London "remember to
always touch in and out, unless it's a bus in which case only touch
in, and unless it's a bendy bus and you have a season ticket then you
don't need to at all", which is unnecessarily complicated.

Neil

--
Neil Williams
Put my first name before the at to reply.

"Neil Williams" wrote in message
...

Is there a feasible way of locking 4 cars out of use on 321
formations, without having to open the above-door panels and lock each
door out manually? The reason I ask is that there is an element of
that takes place on the 0735ish which starts from Bletchley (with the
rear 4 off the platform but unlocked, such that you can't get to
them), and it seems surprising that they wouldn't think of it. That
said, you don't see 12 cars on any of the Tring slows, and they
probably load the heaviest - is there another short platform, e.g.
Apsley/Kings Langley?

I will be interested to find out if the new Desiros have SDO, as SWT's
ones certainly appear to have some form of it to allow calling at
short platforms on the Waterloo-Reading run.

SWT's Desiro SDO is done by switching out whole units, with the guard
controlling it from the front cab of the rearmost unit - but only if he can
get out onto the platform. This leads to the fairly unusual sight of only 4
cars of a 12 car train being opened at some '8 car' platforms e.g Fareham,
because the 3rd unit's cab is alongside the platform ramp.

IIRC the DfT are insisting on GPS controlled individual carriages as the way
ahead, as is done by Southern, with their annoying 'this is carriage number
n of m' type announcements.

Paul

On Sat, 26 Jan 2008 15:37:30 -0000, Paul Scott wrote:

SWT's Desiro SDO is done by switching out whole units, with the guard
controlling it from the front cab of the rearmost unit - but only if he can
get out onto the platform. This leads to the fairly unusual sight of only 4
cars of a 12 car train being opened at some '8 car' platforms e.g Fareham,
because the 3rd unit's cab is alongside the platform ramp.

IIRC the DfT are insisting on GPS controlled individual carriages as the way
ahead, as is done by Southern, with their annoying 'this is carriage number
n of m' type announcements.

And the extended wait for the doors to open at Victoria while the
driver manually overrides the GPS system.