Page 33 - Trafficinfratech Magazine April 2023 Digital Edition

PUBLIC TRANSPORT

which are computationally light placed in the approaches. The
for real time implementation. queue length in each approach is
The system architecture consists calculated from this data, based Bus signal priority
of four components: the remote on traffic flow theory concepts and (BSP) system is
traffic control centre, where the the signal state is directly obtained an operational
priority decision is taken, the bus from the signal control.
that needs priority, the devices Using these information, the bus strategy that
for collecting and communicating arrival time at the traffic signal modifies normal
the data, and the local signal is predicted and chances of bus
controller, through which the final priority are evaluated in the remote traffic signal
signal timings are displayed. Figure control centre. Total person delay operations to better
below shows a schematic diagram with priority is compared with that accommodate
of the bus priority architecture. before priority and only if there is a in-service public
The buses transmit the GPS reduction in total person delay can
position and timestamp to the be achieved, priority is given. In transport buses
remote control centre via wireless that case, the revised signal timing at signalised
General Packet Radio Service at is communicated to the local signal intersections.
a frequency of 1 second. When controller. This communication will
the bus reaches the vicinity of occur only at a buffer time before
intersection (say at a distance of the actual change to occur in the and other ITS applications for on
500 m from the intersection), display. road vehicles. The DSRC system
the On-Broad Unit (OBU) in bus Considering the high data
communicates with the Road Side frequency requirement near the comprises of two types of devices
Unit (RSU) at intersection and signal area, Dedicated Short Range namely, the on-board unit (OBU),
the RSU will then update the bus Communication (DSRC) is utilized installed in buses and road side
position to the remote control to guarantee reliable, low latency unit (RSU), installed on road side
centre. In addition, current travel communication. DSRC is a short- poles near the roadway. For these
times in the signal approaches are range communication standard to be used for the bus priority
obtained using Wi-Fi sensors as that operates in the 5.9 GHz band, system, embedded application was
and when a vehicle with an active designed by CDAC Trivandrum, to developed for collecting and storing
Wi-Fi device crosses the scanners support safety critical applications data from the sensors of OBU.

RSU at the intersection OBU installed inside the bus

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