I asked Dublin bus about their GPS plans, and they send me this standard
response page, which I have reformatted for your convenience.
Real Time Passenger Information System
What is RTPI ?
Traffic congestion in cities makes it difficult for public
transport operators to deliver services according to
schedules. Disruptions to schedules have a negative impact
on the quality of service provided to the customer. This is
a universal problem, experienced in every major city. One
solution being deployed in many cities is the provision of
electronic information displays at bus stops, which give
the customer an estimate of the waiting time for the next
bus. These systems, commonly referred to as Real Time
Passenger Information (RTPI) systems, use a variety of
technologies to track the location of buses in real time
and use this information to generate predictions of the bus
arrivals at stops along the route.
Q-time is the RTPI system currently being implemented by
Dublin Bus. This is a pilot scheme operating on bus routes
in the west of the city. The purpose of the pilot scheme is
to evaluate RTPI in one sector of the network prior to
implementing a citywide RTPI scheme under the NDP.
What routes is Q-time operating on?
The initial phase of Q-time has been implemented on the
Lucan QBC. Electronic displays are installed at key bus
stops on the QBC. The second phase will be installed on the
North Clondalkin and South Clondalkin QBCs during the
summer of 2001. Initially it is planned to have ten
displays on the Lucan QBC and fifteen on the Clondalkin
Benefit to the customer
The customer benefits from the elimination of the
uncertainty regarding the waiting time for the next bus.
The bus stop is equipped with an electronic display unit.
The information displayed indicates the route number, the
destination and the predicted number of minutes for the bus
to arrive at that stop. This information is updated every
How Q-time works
o each bus, using the GPS satellite navigation system,
determines its precise location and transmits this to the
control centre every thirty seconds
o the central computer compares the actual location of the
bus, at a given time, with its scheduled location
o the central computer calculates the time for the bus to
reach all subsequent stops along the route, bearing in mind
the current bus speed and any deviations from the schedule
o the central computer, transmits to the relevant display
units, predicted arrival times for the bus
The main components of the system are:
o an on-bus computer with GPS receiver on each bus
o central computer system, based at the depot
o electronic display units at designated stops
o a VHF radio system to manage communications between the
central computer and the buses and display units.
The Q-time system was developed by a French company, GTMH.
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