On Fri, 11 Apr 2008 13:54:58 -0700 (PDT), Mr Thant
wrote:

On 11 Apr, 19:04, Tom Anderson wrote:
Provided that the bus can get good GPS and GPRS signals. GPS is
notoriously inaccurate in built-up areas, as buildings block lines of
sight to the satellites, and introduce reflections which confuse the
receiver (like ghosting on the telly). I wonder what they're doing to deal
with this?

I've read a TfL paper that I can't find right now that found it to be
surprisingly accurate, something like dead on 98% of the time.
Presumably to do with being aerial mounting a large antenna on the bus
roof where it has a good view of the sky, rather than the tiny
internal one in consumer gear that gets blocked by the car roof.

My general experience of I-Bus has been good even though my route runs
out of the first garage equipped with it so we've had all the bugs and
changes to contend with. There is still the odd bus with non functioning
displays or visual but no audible (or vice versa) announcements. Only
twice has something really silly happened - the first was leaving Wood
Green and I-Bus believing we were still heading there. Even when we
passed ourselves going the other way (IYSWIM) the system did not correct
itself. The other was the system seeming to be completely dead and then
suddenly springing into life after leaving a stop. I have no idea how
GPS works but if it uses any form of cellular pattern to locate a
vehicle I did wonder if we had crossed from one cell to another in the
second example.

Is there a way to tell if a bus is using iBus data or Countdown. Have
any iBus-based displays even been deployed yet?

I-Bus equipped vehicles have a blue and yellow sticker in the
windscreen. There is also a console in the cab - typically just above
and to the right of the driver's head - and this shows the headway gap
and schedule "divergence" on a display to the driver.

I am not aware of a way of knowing if a bus is Countdown equipped as the
bus mounted kit is on the rear axle AIUI. This is one reason for the
unreliability of the system - hard to maintain and takes hours to fix
and means the bus is off the road. Not what an operator under a
performance based contract wants.

I am not aware that any Countdown displays have been integrated into the
I-Bus system yet - I think this part of the project is running late.
Certainly we have some local Countdown displays that are on I-Bus
equipped routes and I have not noticed any substantial change or
improvement to the data. There will be a further 2000 stop displays as
part of I-Bus but this phase is only just out to tender. I don't know if
it incorporates the integration of existing displays as part of the
scope or if it is simply the displays themselves and installation.

--
Paul C


Admits to working for London Underground!

On Fri, 11 Apr 2008 22:36:08 +0100, Paul Corfield
wrote this gibberish:

On Fri, 11 Apr 2008 13:54:58 -0700 (PDT), Mr Thant
wrote:

On 11 Apr, 19:04, Tom Anderson wrote:
Provided that the bus can get good GPS and GPRS signals. GPS is
notoriously inaccurate in built-up areas, as buildings block lines of
sight to the satellites, and introduce reflections which confuse the
receiver (like ghosting on the telly). I wonder what they're doing to deal
with this?

I've read a TfL paper that I can't find right now that found it to be
surprisingly accurate, something like dead on 98% of the time.
Presumably to do with being aerial mounting a large antenna on the bus
roof where it has a good view of the sky, rather than the tiny
internal one in consumer gear that gets blocked by the car roof.

My general experience of I-Bus has been good even though my route runs
out of the first garage equipped with it so we've had all the bugs and
changes to contend with. There is still the odd bus with non functioning
displays or visual but no audible (or vice versa) announcements. Only
twice has something really silly happened - the first was leaving Wood
Green and I-Bus believing we were still heading there. Even when we
passed ourselves going the other way (IYSWIM) the system did not correct
itself. The other was the system seeming to be completely dead and then
suddenly springing into life after leaving a stop. I have no idea how
GPS works but if it uses any form of cellular pattern to locate a
vehicle I did wonder if we had crossed from one cell to another in the
second example.

I was on a 38 the other day that gave it's location correctly at the
stops but always announced that it was going the other way!
messing with the tourists again :-D
--
Mark.
www.MarkVarleyPhoto.co.uk
www.TwistedPhotography.co.uk
www.TwistedArts.co.uk
www.FacelessLadies.com
www.BeautifulBondage.net

MarkVarley - MVP wrote:
I have no idea what they're called, the LED signs in some bus stops
that tell you how long the busses are supposed to be, my question is,
how do they work? how do they update?

A few times I've seen that my bus is due next in a couple of minutes
but it just doesn't arrive, several later busses come and then it
vanishes off the sign, abducted by aliens?

If you read through the archives of this newsgroup you will find similar
statements and much gnashing of teeth. The classic is the bus coming in
the other direction showing up on the display or, during the night, the
bus travelling at much greater than expected speeds and thus the 10
minute allowance for a juicy kebab turns into a rapid dash, without any
greasy and dubious sustenance.

All in all, Countdown is a disappointing experience and while iBus
promises much greater accuracy, it will no doubt lull the average
traveller into a false sense of security much as the present system
does. It would be good if the displays could correct for inaccuracy,
and calculate averages depending on the day and time, well within the
capabilities of even the most modest microcontrollers, but they won't.
Instead, vague promises of an impending bus will remain long after it
has left or will appear well in advance of the actual reality.

ESB

In message , at 17:20:26 on
Fri, 11 Apr 2008, MarkVarley - MVP
remarked:
A few times I've seen that my bus is due next in a couple of minutes
but it just doesn't arrive, several later busses come and then it
vanishes off the sign, abducted by aliens?

Signs like that normally have two modes of operation (but they fail to
explain this).

If the arrival time says "10.35" that means the timetable says there
should be a bus at 10.35. Nothing more.

If the arrival times says "3 minutes" that means they've tracked an
actual bus and it's 3 minutes away.

The former will just scroll off irrespective of the passage of buses.
--
Roland Perry

On 12 Apr, 02:15, Ernst S Blofeld
wrote:

MarkVarley - MVP wrote:
I have no idea what they're called, the LED signs in some bus stops
that tell you how long the busses are supposed to be, my question is,
how do they work? how do they update?

A few times I've seen that my bus is due next in a couple of minutes
but it just doesn't arrive, several later busses come and then it
vanishes off the sign, abducted by aliens?

If you read through the archives of this newsgroup you will find similar
statements and much gnashing of teeth. The classic is the bus coming in
the other direction showing up on the display or, during the night, the
bus travelling at much greater than expected speeds and thus the 10
minute allowance for a juicy kebab turns into a rapid dash, without any
greasy and dubious sustenance.

All in all, Countdown is a disappointing experience and while iBus
promises much greater accuracy, it will no doubt lull the average
traveller into a false sense of security much as the present system
does. It would be good if the displays could correct for inaccuracy,
and calculate averages depending on the day and time, well within the
capabilities of even the most modest microcontrollers, but they won't.
Instead, vague promises of an impending bus will remain long after it
has left or will appear well in advance of the actual reality.

ESB

Yeah, you're right, you might as well just give up, there's no point
in trying to make anything better whatsoever. In fact they might as
well give up on running buses, anyone who needs to get anywhere should
just get a car. I can't see any problem with that idea.

On 12 Apr, 10:36, Roland Perry wrote:

In message , at 17:20:26 on
Fri, 11 Apr 2008, MarkVarley - MVP
remarked:

A few times I've seen that my bus is due next in a couple of minutes
but it just doesn't arrive, several later busses come and then it
vanishes off the sign, abducted by aliens?

Signs like that normally have two modes of operation (but they fail to
explain this).

If the arrival time says "10.35" that means the timetable says there
should be a bus at 10.35. Nothing more.

If the arrival times says "3 minutes" that means they've tracked an
actual bus and it's 3 minutes away.

The former will just scroll off irrespective of the passage of buses.


I'm almost certain that the London Countdown system doesn't have any
capability to work in the first way you describe - i.e. by simply
listing buses according when they should arrive according to the
timetable.

On Fri, 11 Apr 2008, MIG wrote:

Does the use of GPS have implications for Oyster and flat fares?

I don't think so. We had the technical capacity to have non-flat fares
before GPS, and indeed did so. The flares were flattened as an act of
policy, not practical exigency. I suppose with GPS they could introduce
some truly fiendish true-distance-based fare system, but i can't see why
they would.

tom

--
The MAtrix had evarything in it: guns, a juimping off teh walls, flying
guns, a bullet tiem, evil computar machenes, numbers that flew, flying
gun bullets in slowar motian, juimping into a gun, dead police men,
computar hackeing, Kevin Mitnick, oven trailers, a old womans kitchen,
stairs, mature women in clotheing, head spark plugs, mechaanical squids,
Japaneseses assasins, tiem traval, volcanos, a monstar, slow time at
fastar speed, magic, wizzards, some dirty place, Kung Few, fighting,
a lot of mess explodsians EVARYWHERE, and just about anything else yuo
can names!

On Fri, 11 Apr 2008, MIG wrote:

On Apr 11, 6:52*pm, Tom Anderson wrote:
On Fri, 11 Apr 2008, Mizter T wrote:
On 11 Apr, 17:20, MarkVarley - MVP
wrote:

I have no idea what they're called, the LED signs in some bus stops
that tell you how long the busses are supposed to be, my question is,
how do they work? how do they update?

The system is called Countdown, and as part of the iBus project it is
set to become much more reliable and accurate.

Which is a roundabout way of saying that the present system is not very
reliable or accurate :P.

As another poster pointed out, the present system is rather Heath-Robinson
and failure-prone. It was, though, the best that could be done with the
technology of the time it was implemented. Frustrating as it is, it's
better than nothing.

Was it a development of the BESI system used in the 1970s?

Pass!

tom

--
The MAtrix had evarything in it: guns, a juimping off teh walls, flying
guns, a bullet tiem, evil computar machenes, numbers that flew, flying
gun bullets in slowar motian, juimping into a gun, dead police men,
computar hackeing, Kevin Mitnick, oven trailers, a old womans kitchen,
stairs, mature women in clotheing, head spark plugs, mechaanical squids,
Japaneseses assasins, tiem traval, volcanos, a monstar, slow time at
fastar speed, magic, wizzards, some dirty place, Kung Few, fighting,
a lot of mess explodsians EVARYWHERE, and just about anything else yuo
can names!

On Fri, 11 Apr 2008, Mr Thant wrote:

On 11 Apr, 19:04, Tom Anderson wrote:

Provided that the bus can get good GPS and GPRS signals. GPS is
notoriously inaccurate in built-up areas, as buildings block lines of
sight to the satellites, and introduce reflections which confuse the
receiver (like ghosting on the telly). I wonder what they're doing to deal
with this?

I've read a TfL paper that I can't find right now that found it to be
surprisingly accurate, something like dead on 98% of the time.
Presumably to do with being aerial mounting a large antenna on the bus
roof where it has a good view of the sky, rather than the tiny
internal one in consumer gear that gets blocked by the car roof.

Sounds plausible. Also, you don't need an accurate fix all the time: even
if you can only get one every fifty metres, it might do; you could fill in
with dead reckoning in between.

tom

--
The MAtrix had evarything in it: guns, a juimping off teh walls, flying
guns, a bullet tiem, evil computar machenes, numbers that flew, flying
gun bullets in slowar motian, juimping into a gun, dead police men,
computar hackeing, Kevin Mitnick, oven trailers, a old womans kitchen,
stairs, mature women in clotheing, head spark plugs, mechaanical squids,
Japaneseses assasins, tiem traval, volcanos, a monstar, slow time at
fastar speed, magic, wizzards, some dirty place, Kung Few, fighting,
a lot of mess explodsians EVARYWHERE, and just about anything else yuo
can names!

On Fri, 11 Apr 2008, Paul Corfield wrote:

On Fri, 11 Apr 2008 13:54:58 -0700 (PDT), Mr Thant
wrote:

On 11 Apr, 19:04, Tom Anderson wrote:
Provided that the bus can get good GPS and GPRS signals. GPS is
notoriously inaccurate in built-up areas, as buildings block lines of
sight to the satellites, and introduce reflections which confuse the
receiver (like ghosting on the telly). I wonder what they're doing to deal
with this?

I've read a TfL paper that I can't find right now that found it to be
surprisingly accurate, something like dead on 98% of the time.
Presumably to do with being aerial mounting a large antenna on the bus
roof where it has a good view of the sky, rather than the tiny
internal one in consumer gear that gets blocked by the car roof.

My general experience of I-Bus has been good even though my route runs
out of the first garage equipped with it so we've had all the bugs and
changes to contend with. There is still the odd bus with non functioning
displays or visual but no audible (or vice versa) announcements. Only
twice has something really silly happened - the first was leaving Wood
Green and I-Bus believing we were still heading there. Even when we
passed ourselves going the other way (IYSWIM) the system did not correct
itself.

ISTR reading of exactly this failure mode in GPS-driven information
systems on trains, on this very group. Somewhere on SWT? Unbelievable that
the software doesn't catch it.

The other was the system seeming to be completely dead and then suddenly
springing into life after leaving a stop. I have no idea how GPS works
but if it uses any form of cellular pattern to locate a vehicle I did
wonder if we had crossed from one cell to another in the second example.

It doesn't. Unlikely as this may sound, it works by picking up
synchronised radio signals from members of a family of 31 satellites
orbiting 20 000 km above the earth, measuring the time differences between
them with an accuracy of a few nanoseconds, which tells you the
differences in distances to the satellites with an accuracy of a few
metres (out of twenty million - not bad!), then doing geometric
calculations to work out where that means the receiver must be. It's the
kind of thing that if it didn't exist, you'd think it was an absurd idea.
A bit like the London Underground!

Working out your position depends on being able to pick up the signals
from the satellites, and buildings and other features of cities can
interfere with this. I suspect the jumpiness is caused by this: if the bus
has lost the signal for a moment, it won't fire off its announcement until
it's picked it up again and worked out where it is.

tom

--
The MAtrix had evarything in it: guns, a juimping off teh walls, flying
guns, a bullet tiem, evil computar machenes, numbers that flew, flying
gun bullets in slowar motian, juimping into a gun, dead police men,
computar hackeing, Kevin Mitnick, oven trailers, a old womans kitchen,
stairs, mature women in clotheing, head spark plugs, mechaanical squids,
Japaneseses assasins, tiem traval, volcanos, a monstar, slow time at
fastar speed, magic, wizzards, some dirty place, Kung Few, fighting,
a lot of mess explodsians EVARYWHERE, and just about anything else yuo
can names!