Dublin Bus provides service throughout Dublin City and County Dublin (922 km2) with some services extending into neighbouring counties of Meath, Kildare and Wicklow. The vehicles provide service to the wider population of 1.5 million people, operating 1,100 vehicles on 220 mostly radial routes into the city. Dublin Bus operates a predominantly double-decker fleet to carry its 150 million passengers each year.
Dublin Bus has many services that begin, end or go through the city, so dealing with traffic congestion is a major issue. The organisation requires a communication solution that will help to ensure that buses are on schedule or as close to schedule as possible. A primary goal of the project was to implement a real-time display and control system that would allow inspectors to improve the quality of service.
Historically, Dublin Bus has placed an importance on ensuring vehicles begin and complete routes on schedule, but has not always been able to track the success of the intermediary stages of a journey. They needed to be able to capture data that would ensure its vehicles are consistently arriving on-time to all stops on a route.
Meanwhile bus passengers had to plan their journeys with timetables that offered only historical information. Dublin Bus wanted to offer patrons up-to-date, real-time scheduling before they leave home, while at bus stops and also ensuring that passengers on board knew which location the next stop would be.
The organisation moved to improve communications between dispatch staff and drivers when it installed a six-site TaitNet MPT 1327 trunked radio system mostly for voice calls. Tait mobile radios are installed in buses and control centres, and 100 Tait portable radios are also carried by supervisors and maintenance staff.
Subsequently Dublin Bus has moved to deploy Automatic Vehicle Location (AVL) throughout the fleet. It was able to implement an AVL system using the current MPT infrastructure with the TaitNet Data System (TNDS) by adding five extra TDMA channels to carry position polling data.
The sites have been designed to accommodate 30-second polling frequency automatic location updates which occur seamlessly via the same radio used for voice communications. The highly efficient switching of the Tait radio allows this to occur at a speed unnoticeable to the drivers. In addition the infrastructure has the facility for dynamic frame linked extension, which ensures that larger-than-expected radio traffic volumes can be accommodated without interrupting the data flow.
The Tait TM8235, mobile radio has since been used to replace the existing T2030 mobiles because of its data capabilities and ability to communicate over MAP27 with the INIT on-board COPILOT. Importantly during the staged rollout of the TM8235, drivers could still utilise the T2030 radio to maintain voice contact with supervisors and controllers.
With the TM8235 Tait also introduced rear port programming, which enables the on-board computer to accommodate software updates sent via wireless LAN. Previously, to update any software in bus applications, such as radios, Dublin Bus had to go through the expensive and time-consuming method of bringing an entire fleet into the workshop to carry out manual updates.
Dublin Bus is piloting the AVL system on one of its routes before a wider city rollout is planned. Data obtained from the AVL will be used allow the company to plan route structures, amend services when needed and to pass on real-time information to passengers.
This positioning paper will provide a summarized comparison of the current digital technologies outlining the advantages and disadvantages for each of them. The technologies compared are DMR, dPMR, TETRA, TETRAPOL, P25, NXDN and Opensky.