Can anyone tell me how the digital displays at some London bus stops work?
The ones that estimate how long the next bus will take to get there? What
kind of connection are they maintaining with the bus etc? I'm very curious
how it works, I haven't seen that before.

any info appreciated,
John.

The system is called Countdown. It mainly works through a system called AVL
(Automatic Vehicle Location). This system uses transponders on the bus that
communicate with beacons stuck to lampposts along the route (little grey
boxes). This data gets sent to the home garage and then to the bus stops.
The arrival time is then worked out by comparing this data to the timetable.
I have heard rumours that this will be replaced by a GPS based system soon.

"john" wrote in message
...
Can anyone tell me how the digital displays at some London bus stops work?
The ones that estimate how long the next bus will take to get there? What
kind of connection are they maintaining with the bus etc? I'm very curious
how it works, I haven't seen that before.

any info appreciated,
John.

On Sat, 2 Aug 2003 17:59:03 +0100, "Richard Jeeves"
wrote:

The system is called Countdown. It mainly works through a system called AVL
(Automatic Vehicle Location). This system uses transponders on the bus that
communicate with beacons stuck to lampposts along the route (little grey
boxes). This data gets sent to the home garage and then to the bus stops.
The arrival time is then worked out by comparing this data to the timetable.
I have heard rumours that this will be replaced by a GPS based system soon.

"

Unlikely. London Buses did a technical review 18 months ago which
endorses the beacon approach.

The system which gives priority to buses at traffic lights is being
converted from inductive loop/transponder technology to beacons
progressively.

Rob.
--
rob at robertwoolley dot co dot uk

On Sun, 3 Aug 2003 03:22:49 +0100 John Rowland wrote:
} "Robert Woolley" wrote in message
} ...
}
} The system which gives priority to buses at traffic lights
} is being converted from inductive loop/transponder
} technology to beacons progressively.
}
} I wasn't aware such a system existed. When I rode the T4 from Feltham to,
} er, T4, I noticed that no such system was in place, despite having been
} promised in publicity. Where could I see concrete evidence of the system in
} operation? (Not including the bus gate in Claygate, whose bollard and
} traffic lights clearly are controlled by approaching buses.)

On the eastern part of Broadway, Stratford there's a bus lane with
separate lights from the 3 other lanes. It allaows the busses to filter
left (east) before other traffic.

Is that the sort of thing you meant?

Matthew
--
Il est important d'être un homme ou une femme en colère; le jour où nous
quitte la colère, ou le désir, c'est cuit. - Barbara

http://www.calmeilles.co.uk/

On Sun, 3 Aug 2003 03:22:49 +0100, "John Rowland"
wrote:

"Robert Woolley" wrote in message
.. .

The system which gives priority to buses at traffic lights
is being converted from inductive loop/transponder
technology to beacons progressively.

I wasn't aware such a system existed. When I rode the T4 from Feltham to,
er, T4, I noticed that no such system was in place, despite having been
promised in publicity. Where could I see concrete evidence of the system in
operation? (Not including the bus gate in Claygate, whose bollard and
traffic lights clearly are controlled by approaching buses.)


Converted sites usually have a beacon 50m upstream of the signals.
The beacon is mounted on a post of its own.

For inductive loop sites, there is no physical evidence.

Rob.
--
rob at robertwoolley dot co dot uk

"Robert Woolley" wrote in message
...
On Sun, 3 Aug 2003 03:22:49 +0100, "John Rowland"
wrote:

"Robert Woolley" wrote in message
.. .

The system which gives priority to buses at traffic lights
is being converted from inductive loop/transponder
technology to beacons progressively.

I wasn't aware such a system existed.
Where could I see concrete evidence of the system in
operation? (Not including the bus gate in Claygate,

I meant Clayhall...

Converted sites usually have a beacon 50m upstream of the signals.
The beacon is mounted on a post of its own.

For inductive loop sites, there is no physical evidence.

Thanks, but I wasn't at all clear: when I said "concrete evidence" I didn't
mean visible infrastructure, I just meant that if I stood at the traffic
lights I would see them change whenever a bus came along.

--
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

On Sun, 3 Aug 2003 14:54:07 +0100, "John Rowland"
wrote:

Thanks, but I wasn't at all clear: when I said "concrete evidence" I didn't
mean visible infrastructure, I just meant that if I stood at the traffic
lights I would see them change whenever a bus came along

Not necessarily. The effect of SVD (Selective Vehicle detection) is
to a) shorten the red time to buses b) extend the green time.

Rob.
--
rob at robertwoolley dot co dot uk

Along the bus route are beacons, as the bus passes these beacons a signal is
transferred from the bus to the beacon then to a central computer then to
the bus stop.
ice
"john" wrote in message
...
Can anyone tell me how the digital displays at some London bus stops work?
The ones that estimate how long the next bus will take to get there? What
kind of connection are they maintaining with the bus etc? I'm very curious
how it works, I haven't seen that before.

any info appreciated,
John.