Transport for LondonBackground
In addition, passenger expectations have risen.
Greater accessibility, more reliable services and effective journey information are called for.
Therefore iBus, one of the world's largest integrated Automatic Vehicle Location (AVL) projects, was introduced, revolutionising how bus services are delivered and monitored in London.
iBus keeps track of where London's buses are, allowing bus controllers to regulate services to make them more reliable.
It does this using a combination of technologies to deliver the accuracy required from the AVL part of the system, including Global Positioning System (GPS) satellite technology and 'map matching' with inputs from a Gyroscope and the buses speedometer/odometer.
Controllers can keep track of where a bus is and take action to improve its reliability
The bus data radio uses GPRS to send the location of the bus about every 30 seconds to a central computer system. This system passes on the bus location information to service controllers who maintain the bus performance along the entire route.
The central computer system also predicts the time it will take for buses to arrive at bus stops. This means the bus's arrival can be displayed on Countdown signs at key bus shelters.
Each bus has a powerful computer that is able to correct possible problems using satellite based GPS in a city environment. We call this our enhanced location system.
Stored in its computer, every bus carries the details of all the stop and destination names for each route.
As the bus computer continually tracks its position along the route, these names are announced and displayed on signs inside the bus.
Where places of interest such as hospitals are close to a stop this information is also announced and displayed.
Each bus also has a voice radio for communication between the bus driver and their service controller, and data radios that send information to our central computer systems.
We also send data directly to traffic lights where timings can be altered to help speed up buses. This has the added benefit of reducing congestion problems.
