GVB continually improves transportation service quality over years with PSItraffic
We protect critical infrastructure - for sure!
In addition to almost 800,000 residents, ten million tourists visit the Dutch city of Amsterdam and its surroundings every year. As the largest municipal transportation company in the Netherlands, the GVB Amsterdam (Gemeente Vervoer Bedrijf) transports almost one million passengers every day using 640 vehicles in the metropolitan area. Today, the network includes over 50 Bus lines, 16 tram lines and 4 subway lines, as well as 5 ferry connections.
New hardware and software
At the beginning of the new millennium, busses and trams were equipped with new on-board computers. The old control system had seen better days and was no longer capable of meeting the needs of a modern public transportation company. The new computers were to be connected to a modern, powerful Intermodal Transport Control System (ITCS) to increase service quality and improve passenger information. The Berlin PSI Transcom GmbH was granted the contract in August 2002 to create a new operations control system based on their system platform PSItraffic.
The contract contained standard functions, such as constant monitoring of vehicle positions and operational status, as well as the display of dynamic passenger information. It also included special solutions for integrating existing infrastructure, such as setting rail switches. Programming was required for the large number of interfaces, e.g. a connection to analog radio, driver login for on-board computers, and for planning data or statistics.
The GVB commissioned the new ITCS (Intermodal Transport Control System) in 2005.
Since then, the requirements of the municipality of Amsterdam for forecast quality of projected arrival times displayed at the stops, has only increased. On-time requirements have also grown more demanding. Amsterdam has a bonus-malus system that imposes fines on the transport company when they fail to provide service or to achieve a defined on-time rate. René Rothe, sales manager at PSI Transcom, says from experience: "When I know my city, I know when and in which direction traffic flows. I can adjust the headway of busses and trams accordingly." In this way, one can provide a bus the opportunity to cover its route at 20 km/hr. It is necessary to make both software and organizational changes to the schedule.
Sophisticated functions, such as the control of regularity, contribute to the improvements. A tram line consists of a particular number of stations. These so-called runs are served by 10 or 20 vehicles with a particular headway. If there is a fault in the run, the trams back up. When they are finally able to continue, a whole group arrives together at the final stop. Since it does not make much sense to send them all back together on the return trip, the ITCS includes the service Regularity, which equalizes traffic. At the terminal stations, it shows the drivers their new departure time on the so-called EndPointHourse, so that they can undertake the return trip at their approximate correct intervals. PSItraffic displays changes automatically on the stop displays.
A similar function is performed by the automatic rail switch control at certain terminals and, in particular, the central station. There, at the most important transportation hub in Amsterdam, there are four tracks for the trams to the platforms on which two trains can stop. However, access to these tracks is single-tracked. It may occur that the lines one and five arrive in this order, but according to the timetable must depart in the reverse order. Based on reported position information, PSItraffic creates an arrival order to the platforms which guarantees the scheduled departure, while controlling the switches accordingly. The system automatically presents the changes on the information displays.
If faults occur on the track, the ITCS can plan a detour so that the train reaches its goal. Since rerouting is not possible from every stop, the dispatcher in the control center must activate a sensible detour. As a rule, these are pre-defined routes that the system switches automatically. However, the dispatcher can also activate detours between two points as needed. In general, the action of the dispatcher triggers an avalanche of actions: The system updates the route, calculates the new departure times, corrects the switch settings, and presents the changes over the entire route in the stop displays.
Continuous position updates
Since the contract was awarded by the city of Amsterdam, an ongoing partnership has existed between GVB and PSI Transcom. "Since Amsterdam’s needs continue to grow, we need a reliable partner to provide robust support", says Wouter van Lohuizen, Chain Manager EBS at GVB. For example, the on-time and quality requirements were increased in the previous year. And the Berliners were again able to achieve improvements. The location reports are based on information from the on-board computers, GPS data, speed measurements, sensors on the wheels, and gyroscopes. If the speed is too high or too low, the results can be imprecise, and with over 600 GVB vehicles, even small inaccuracies are enough to shift the position of a vehicle in the arrival list by one or two positions to the front or back.
This, in turn, endangers the overall switch control system. For this reason, the number of datagrams was increased again. To circumvent the position algorithm of the on-board computer, each vehicle sends an additional datagram upon leaving the stop. This information is collected by PSItraffic, which uses it for the position displays and the calculation of arrival and departure times. Whenever a position report arrives in the system, the current trip is calculated, as are the next two. It takes into account higher or lower speeds, as well as longer stops at the terminal stations.
Precise information and savings
GVB has not been required to pay any fines in the last several years as a result of the bonus-malus system in the city of Amsterdam. On the contrary, two years ago the city returned a significant sum. And Wouter van Lohuizen is certain: "We have achieved much in the last few years and are also well positioned for the future to provide our passengers with the best services.