On Thu, 12 May 2005, John Rowland wrote:

"Tom Anderson" wrote in message
...
On Thu, 12 May 2005, John Rowland wrote:

"Stuart" wrote in message
news
I suspect it's the same system with 'satellite' being used as a
bit of hyperbole

Parabole, surely.

Parabolic orbits are open (ie end up shooting off into deep space),
and so not much use for satellites. Personally, i'd never let such a
technically inaccurate pun pass my ellipse.

Satellite *dishes* are parabolic.

Doh! Of course. I wonder why i immediately started thinking about orbital
mechanics? Too much Star Trek as a kid, probably.

tom

--
Gotta treat 'em mean to make 'em scream.

On Thu, 12 May 2005, Dave Arquati wrote:

Stuart wrote:
Vernon wrote:

When LBC Travel News talk of travel information derived from
"Satellite Data", what sort of satellite help are they getting? I am
aware of GPS for navigation, but I can't see how that could help with
determining the levels of realtime traffic problems.

Just curious, but does anyone here know?

Years ago they used to have 'real time travel data' which was linked
to the Trafficmaster system. This monitored the speed of individual
cars from point A to point B (while making the actual registration
number anonomous) to give a journey time.

Don't TfL do this with the congestion charge cameras too, i.e. measure
the journey times of individual cars between two cameras to get traffic
information for particular links?

I always thought that these traffic-monitoring systems should be
integrated somewhat with the London Buses data. At the moment, the
London Buses realtime information is not particularly realtime, and
generally only talks about roadworks, scheduled diversions and scheduled
disruptive events like demonstrations. I'd like to know how congested a
given link is, so I can plan my bus journey to avoid it, or use the Tube
instead.

A very impressive system would be to not only have accurate Countdown
information online and at stops, but also to have dynamically-estimated
journey times to destinations from that stop, available both online and
via Countdown at the stop itself. Integrate this into Journey Planner
for those looking for journeys departing "now", and you get an extremely
accurate guide as to the quickest way to your destination.

This is what we call a 'pipe dream' . Yes, this would be very cool, but
the amount of effort it would require to gather the traffic data, process
it to produce congestion forecasts (not entirely unlike weather
forecasting - congestion is a dynamic, nonlinear, mobile phenomenon), work
out delays to services and distribute this to every bus-stop would be
substantial.

Integrating into the online planner would also, i imagine, be very
difficult - it's the sort of thing that sounds easy, but is often
fiendishly difficult in practice, since the planner software will be built
around the assumption of a static database, rather than one which changes
every minute.

How would countdown display the delay information? There are dozens of
destinations for each bus; would it go through all of them? Key stops?
Stops affected by delays?

Anyway, having said all that, this is a good idea, and i'd imagine bits of
it will be implemented in the future.

tom

--
Gotta treat 'em mean to make 'em scream.

I suspect it's the same system with 'satellite' being used as a
bit of hyperbole

Parabole, surely.

Parabolic orbits are open (ie end up shooting off into deep space),
and so not much use for satellites. Personally, i'd never let such a
technically inaccurate pun pass my ellipse.

Satellite *dishes* are parabolic.

Doh! Of course. I wonder why i immediately started thinking about orbital
mechanics? ...

Well, what *else* would anyone think of when different conic sections
are mentioned in connection with satellites?

Besides, dish antennas are three-dimensional, hence paraboloidal.

Too much Star Trek as a kid, probably.

And since when did anything in Star Trek ever have anything to do with
actual orbital mechanics?
--
Mark Brader | "[Jupiter's] satellites are invisible to the naked eye
Toronto | and therefore can have no influence on the Earth
| and therefore would be useless
| and therefore do not exist." -- Francesco Sizi

Tom Anderson wrote:
On Thu, 12 May 2005, Dave Arquati wrote:


Stuart wrote:

Vernon wrote:


When LBC Travel News talk of travel information derived from
"Satellite Data", what sort of satellite help are they getting? I am
aware of GPS for navigation, but I can't see how that could help with
determining the levels of realtime traffic problems.

Just curious, but does anyone here know?

Years ago they used to have 'real time travel data' which was linked
to the Trafficmaster system. This monitored the speed of individual
cars from point A to point B (while making the actual registration
number anonomous) to give a journey time.

Don't TfL do this with the congestion charge cameras too, i.e. measure
the journey times of individual cars between two cameras to get traffic
information for particular links?

I always thought that these traffic-monitoring systems should be
integrated somewhat with the London Buses data. At the moment, the
London Buses realtime information is not particularly realtime, and
generally only talks about roadworks, scheduled diversions and scheduled
disruptive events like demonstrations. I'd like to know how congested a
given link is, so I can plan my bus journey to avoid it, or use the Tube
instead.

A very impressive system would be to not only have accurate Countdown
information online and at stops, but also to have dynamically-estimated
journey times to destinations from that stop, available both online and
via Countdown at the stop itself. Integrate this into Journey Planner
for those looking for journeys departing "now", and you get an extremely
accurate guide as to the quickest way to your destination.


This is what we call a 'pipe dream' .

Aw, you're ruining my fun.

Yes, this would be very cool, but
the amount of effort it would require to gather the traffic data, process
it to produce congestion forecasts (not entirely unlike weather
forecasting - congestion is a dynamic, nonlinear, mobile phenomenon), work
out delays to services and distribute this to every bus-stop would be
substantial.

I don't (think I) mean forecasting congestion, as such... just using
data on current traffic speeds to estimate those journey times. The data
collectors are already out there in the form of on-bus AVL, C-charge
cameras, TfL traffic cameras, RAC info etc.

For example, if traffic is crawling eastbound on Kensington Road, then
the system will flag it up as "slower than usual" and send that
information to London Buses, who can then identify which routes are
affected (9, 10 and 52 eastbound).

The current estimated journey time through the congested link can be
compared to the timetabled journey time, and any significant difference
can then be relayed to relevant terminals (the website, WAPsite, all
eastbound 9, 10 and 52 buses which haven't yet reached Kensington Road,
and Countdown displays at all 9, 10 and 52 stops west of Kensington
Road). That information just needs to be a fixed time increase for an
individual link, and only needs to be sent out when the time increase is
significant (say over 50%).

So, if journey times along Kensington Road (which exists as a defined
link in the database, say between Queens Gate and Scotch House) are
timetabled for 8 minutes, and are taking an estimated 13 minutes instead
(based on traffic speeds), then a "Kensington Road: +5" flag gets sent
out to the relevant stops and buses.

If you are waiting at Kensington High Street, you will see Countdown
scrolling journey times to key destinations across the bottom of the
screen ("Knightsbridge X+5 mins, Picc Circus X+5 mins, Paddington X
mins") as appropriate. Alternatively it may be easier to understand if
it just shows "Routes 9, 10, 52: 5 mins delay past Knightsbridge".

Integrating into the online planner would also, i imagine, be very
difficult - it's the sort of thing that sounds easy, but is often
fiendishly difficult in practice, since the planner software will be built
around the assumption of a static database, rather than one which changes
every minute.

That's true, but Journey Planner already integrates the existing
real-time info into journey suggestions. Let's say this journey time
info is in a database where each link has a field with a delay property
which is either 0 or a delay in minutes.

I'm not sure how the JP works, but presumably when it returns a route,
it is composed of a series of links already. So when you look up
Kensington High St to Trafalgar Square bus bus, you get the appropriate
links between those places returned. All JP has to do is look up the
delay for each link.

How would countdown display the delay information? There are dozens of
destinations for each bus; would it go through all of them? Key stops?
Stops affected by delays?

That's an area for customer research attention :-) The limitation is
really the size of the display. Countdown isn't that big, so you might
have to devote just the bottom line to reporting delays to specific
routes as I suggested above.

If a larger screen were available, e.g. an LCD at a bus station, then
that could display estimated journey times to all key destinations.

Online or by WAP, you could enter your current stop (or get it filled in
automatically if you have a 3G phone, I think) and destination, and get
a personal estimated journey time.

Anyway, having said all that, this is a good idea, and i'd imagine bits of
it will be implemented in the future.

I hope so! I really hope they introduce "next stop" information inside
buses ASAP, because I think that's the single most important improvement
to be made.

The other stuff would be pretty cool though :-)

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

"Vernon" wrote in message
...
When LBC Travel News talk of travel information derived from "Satellite
Data", what sort of satellite help are they getting? I am aware of GPS
for
navigation, but I can't see how that could help with determining the
levels
of realtime traffic problems.

Just curious, but does anyone here know?




I'm not sure which of these two is the non-professional version of RTT Nik
refers to. They both seem to be trials and often don't agree with one
another precisely!

http://www.trafficmap.co.uk/
http://www.highways.gov.uk/trafficinfo/ and choose current traffic
conditions

For a system that shows a map of bus routes with where the buses are (well
actually trams mostly) and you can hover on a vehicle to find out where it's
stopping next and also on stops to find what's due have a look at:

http://www.nextbus.com/predictor/stopSelector.jsp# then click on live map.
It's not all the transit in San Francisco but it is all the street cars (but
not the cable cars).

On Sat, 14 May 2005, Dave Arquati wrote:

Tom Anderson wrote:
On Thu, 12 May 2005, Dave Arquati wrote:

A very impressive system would be to not only have accurate Countdown
information online and at stops, but also to have
dynamically-estimated journey times to destinations from that stop,
available both online and via Countdown at the stop itself.

Yes, this would be very cool, but the amount of effort it would
require to gather the traffic data, process it to produce congestion
forecasts (not entirely unlike weather forecasting - congestion is a
dynamic, nonlinear, mobile phenomenon), work out delays to services
and distribute this to every bus-stop would be substantial.

I don't (think I) mean forecasting congestion, as such... just using
data on current traffic speeds to estimate those journey times.

Ah, but that does involve forecasting - if you want to know about delays
that a 38 at Victoria might suffer when it gets to Hackney, you need to
have some idea of what the traffic is going to be like about 45 minutes
into the future.

On the flip side, it's quite likely TfL are already doing this forecasting
as part of their realtime congestion management work.

The data collectors are already out there in the form of on-bus AVL,
C-charge cameras, TfL traffic cameras, RAC info etc.

Is that network dense enough? The CC cameras are only in a ring round the
zone (and possibly inside it - but not much outside it) and TfL and RAC
cameras are only on major arterial routes. The AVL data, though, would
cover all the roads you needed to know about - pretty much by definition!

Integrating into the online planner would also, i imagine, be very
difficult - it's the sort of thing that sounds easy, but is often
fiendishly difficult in practice, since the planner software will be
built around the assumption of a static database, rather than one
which changes every minute.

That's true, but Journey Planner already integrates the existing
real-time info into journey suggestions.

Ah, didn't realise that. Okay, in that case, it should be pretty easy.

tom

--
We'll never win by being like them. Our best tactic is to be better. Better necessarily means different. -- Jon Rentzsch

Tom Anderson wrote:
On Sat, 14 May 2005, Dave Arquati wrote:


Tom Anderson wrote:

On Thu, 12 May 2005, Dave Arquati wrote:


A very impressive system would be to not only have accurate Countdown
information online and at stops, but also to have
dynamically-estimated journey times to destinations from that stop,
available both online and via Countdown at the stop itself.

Yes, this would be very cool, but the amount of effort it would
require to gather the traffic data, process it to produce congestion
forecasts (not entirely unlike weather forecasting - congestion is a
dynamic, nonlinear, mobile phenomenon), work out delays to services
and distribute this to every bus-stop would be substantial.

I don't (think I) mean forecasting congestion, as such... just using
data on current traffic speeds to estimate those journey times.


Ah, but that does involve forecasting - if you want to know about delays
that a 38 at Victoria might suffer when it gets to Hackney, you need to
have some idea of what the traffic is going to be like about 45 minutes
into the future.

I don't think that's entirely necessary (although it would certainly be
impressive!). Knowing about existing delays on the route will give
vastly superior realtime information to that currently available - so if
congestion is already occurring in Hackney, it would be highlighted at
the 38 stop at Victoria, on the assumption that congestion tends to
clear slowly.

If, say, congestion then arises in Hackney whilst the 38 is en route at
TCR, then an on-board information system (probably using the new video
screens appearing in buses) can dispense this information to the
passengers, who can then make their own minds up about any route
changes. Messages could also be sent out to people who have signed up to
have their routes to/from work tracked for disruptions - this is already
done for Tube lines via email or SMS, and I imagine it could be easily
extended to bus routes.

On the flip side, it's quite likely TfL are already doing this forecasting
as part of their realtime congestion management work.

I wonder how they would do it. Weather forecasting involves predicting
movements of fronts and such (although I know very little about it!),
but congestion forecasting would seem more difficult as it can arise
much more spontaneously - e.g. if a lorry breaks down in an awkward
location.

Maybe I should make this my Masters project next year... I know a couple
of friendly computing/information systems students who might like to
collaborate!

The data collectors are already out there in the form of on-bus AVL,
C-charge cameras, TfL traffic cameras, RAC info etc.


Is that network dense enough? The CC cameras are only in a ring round the
zone (and possibly inside it - but not much outside it) and TfL and RAC
cameras are only on major arterial routes. The AVL data, though, would
cover all the roads you needed to know about - pretty much by definition!

I heard somewhere that TfL already track vehicle speeds through the
C-charge area by using the cameras, although I don't know quite what
they track. AVL data seems like the most obvious choice, but is somewhat
restricted on roads used by few or infrequent buses, as one bus behaving
erratically could seriously skew the data. Speeds of all vehicles would
be more useful - that can be obtained either via digital speed cameras
(which could presumably be set to log all vehicle speeds) or via those
tubes you sometimes see across the road, which are used to check traffic
speeds (although they are far from infallible).

(snip)


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

On Sun, 15 May 2005, Dave Arquati wrote:

Tom Anderson wrote:
On Sat, 14 May 2005, Dave Arquati wrote:

Tom Anderson wrote:

On Thu, 12 May 2005, Dave Arquati wrote:

A very impressive system would be to not only have accurate
Countdown information online and at stops, but also to have
dynamically-estimated journey times to destinations from that stop,
available both online and via Countdown at the stop itself.

Yes, this would be very cool, but the amount of effort it would
require to gather the traffic data, process it to produce congestion
forecasts (not entirely unlike weather forecasting - congestion is a
dynamic, nonlinear, mobile phenomenon), work out delays to services
and distribute this to every bus-stop would be substantial.

I don't (think I) mean forecasting congestion, as such... just using
data on current traffic speeds to estimate those journey times.

Ah, but that does involve forecasting - if you want to know about
delays that a 38 at Victoria might suffer when it gets to Hackney, you
need to have some idea of what the traffic is going to be like about 45
minutes into the future.

I don't think that's entirely necessary (although it would certainly be
impressive!). Knowing about existing delays on the route will give
vastly superior realtime information to that currently available - so if
congestion is already occurring in Hackney, it would be highlighted at
the 38 stop at Victoria, on the assumption that congestion tends to
clear slowly.

Okay. I'm dubious about this; it will warn people about problems that
won't affect them, and fail to warn them about problems which will.
However, it's better than nothing, which is what we have now.

There's a case to be made that it's better than forecasting - forecasting
necessarily means telling people things you don't know to be true, but are
basically guesses. Telling them possibly irrelevant truths is
straightforward and honest, even if it does lumber them with more
working-out to do themselves.

One crucial quantitative factor is the volatility of congestion; if the
typical lifetime of congestion is longer than the length of the bus's
route, then it's worth telling peole about congestion that's occuring now.
If it's not, it isn't. And i don't know if it is.

On the flip side, it's quite likely TfL are already doing this
forecasting as part of their realtime congestion management work.

I wonder how they would do it. Weather forecasting involves predicting
movements of fronts and such (although I know very little about it!),
but congestion forecasting would seem more difficult as it can arise
much more spontaneously - e.g. if a lorry breaks down in an awkward
location.

True. However, congestion that's not related to accidents might be
predictable, and the degree to which an accident could generate congestion
(congestion potential, if you will) might be.

Maybe I should make this my Masters project next year... I know a couple
of friendly computing/information systems students who might like to
collaborate!

Please do.

No, wait! I never uses buses - work on something to do with tubes or
bikes. Cheers.

tom

--
People don't want nice. People want London. -- Al

Tom Anderson wrote:
On Sun, 15 May 2005, Dave Arquati wrote:

Tom Anderson wrote:

On Sat, 14 May 2005, Dave Arquati wrote:

Tom Anderson wrote:

On Thu, 12 May 2005, Dave Arquati wrote:

A very impressive system would be to not only have accurate
Countdown information online and at stops, but also to have
dynamically-estimated journey times to destinations from that
stop, available both online and via Countdown at the stop itself.


Yes, this would be very cool, but the amount of effort it would
require to gather the traffic data, process it to produce
congestion forecasts (not entirely unlike weather forecasting -
congestion is a dynamic, nonlinear, mobile phenomenon), work out
delays to services and distribute this to every bus-stop would be
substantial.


I don't (think I) mean forecasting congestion, as such... just using
data on current traffic speeds to estimate those journey times.


Ah, but that does involve forecasting - if you want to know about
delays that a 38 at Victoria might suffer when it gets to Hackney,
you need to have some idea of what the traffic is going to be like
about 45 minutes into the future.


I don't think that's entirely necessary (although it would certainly
be impressive!). Knowing about existing delays on the route will give
vastly superior realtime information to that currently available - so
if congestion is already occurring in Hackney, it would be highlighted
at the 38 stop at Victoria, on the assumption that congestion tends to
clear slowly.

Okay. I'm dubious about this; it will warn people about problems that
won't affect them, and fail to warn them about problems which will.
However, it's better than nothing, which is what we have now.

My assumption is that the problems that will affect them will be relayed
to them as soon as those problems happen, but otherwise it's difficult
to predict such problems.

There's a case to be made that it's better than forecasting -
forecasting necessarily means telling people things you don't know to be
true, but are basically guesses. Telling them possibly irrelevant truths
is straightforward and honest, even if it does lumber them with more
working-out to do themselves.

One crucial quantitative factor is the volatility of congestion; if the
typical lifetime of congestion is longer than the length of the bus's
route, then it's worth telling peole about congestion that's occuring
now. If it's not, it isn't. And i don't know if it is.

I think it is - but I'd need to do some research to be sure (and I'm
supposed to be researching something else at the moment, so it may have
to wait!). Traffic delays seem to last for a long time after that which
caused the delay has disappeared. I found the following simulation
extremely entertaining:
http://vwisb7.vkw.tu-dresden.de/~tre.../simFrame.html

Perhaps we can say there are two types of traffic delay: (a) those due
to lack of sufficient network capacity, and (b) those due to
spontaneously-arising problems like vehicles blocking the road. The
former can be forecast by their nature, and can probably be forecast
some time in advance - to some extent, these will already be
incorporated into the bus timetable (e.g. rush hours). The latter cannot
be forecast, but once they occur, the delays they cause can be monitored
and the travelling public alerted.

On the flip side, it's quite likely TfL are already doing this
forecasting as part of their realtime congestion management work.


I wonder how they would do it. Weather forecasting involves predicting
movements of fronts and such (although I know very little about it!),
but congestion forecasting would seem more difficult as it can arise
much more spontaneously - e.g. if a lorry breaks down in an awkward
location.


True. However, congestion that's not related to accidents might be
predictable, and the degree to which an accident could generate
congestion (congestion potential, if you will) might be.

Ooh, "congestion potential"... I love it when people talk
scientifically... :-) I was just thinking that such network analysis is
probably similar to metabolic flux analysis in my field, and a standard
set of equations are probably applicable. Mind you, I'm sure this has
all been studied before.

Maybe I should make this my Masters project next year... I know a
couple of friendly computing/information systems students who might
like to collaborate!

Please do.

No, wait! I never uses buses - work on something to do with tubes or
bikes. Cheers.

The Tube's no fun; it either breaks down or it doesn't, there's no
delicious in-between you can model!

For bikes... perhaps an improved Journey Planner which knows traffic
levels on roads across the city, and allows you to specify a maximum
traffic level you'll cycle through, allowing you to plan routes to avoid
unpleasantly busy roads like the Euston Road. You could chuck in
pollution indices too if you like.

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

"Mark Brader" wrote in message
...

--
Mark Brader | "[Jupiter's] satellites are invisible to the naked eye
Toronto | and therefore can have no influence on the Earth
| and therefore would be useless
| and therefore do not exist." -- Francesco Sizi

LOL. One of your best (and not for lack of competition either).

--
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