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