Updated 2003

Helsinki Public Transport Signal Priority and 
Passenger Information (HeLMi)

The new public transport telematic system called HeLMi (Pearl) was launched in Helsinki in the year 1999. The pilot stage of the project was known as "Project-423" because tram line 4 and bus line 23 was the first routes used in the new system. The project is driven by Helsinki City Transport (HKL) and Traffic Planning Division of the City of Helsinki.
    
The new telematic system HELMI provides several public transport telematic functions as real time passenger information, bus and tram priority at traffic signals and the schedule monitoring. Although similar systems are used in several European cities, HELMI telematic system is one of the most sophisticated because it is based almost solely on the wireless communication with radio modems.

The public transport telematic has been accepted as new instrument to increase the attraction of the usage of buses even in smaller cities as Västerås and Jönköping in Sweden. In the Nordic countries the largest public transport telematic system including all of the bus and tram lines of the city is used in Gothenburg.

System Configuration of the Project  HeLMi  

Characteristics of telematics

The corner stone of the telematic system is the location of the bus. It is determined in three steps: 

• GPS-satellite navigation plots the bus roughly on the right bus stop window (a section of the route before and after the bus stop)
  

• Bus door opening at the bus stop locates the bus exactly on the right position along the route. 
  

• The bus location along the route is based on the odometer counting the accurate distance of the bus from the preceding bus stop 

Each bus is polled by the central equipment every tenth second. So the central computer has continuously the data of the exact position of each bus along the route.

Schedule monitoring is based on the comparison of the real location of the bus to the location calculated from the schedule. The difference indicated as seconds at the driver display is updated continuously.

The same indication is sent also to the fleet management room at ten second intervals. The fleet manager can follow the progress of all buses along the line and give some instructions to the any bus driver if some disturbances are found. 

Vehicle location monitoring is based on the data of the updated position of each vehicle. The monitoring screen is shown on the right. Each row represents a single stop. The stop name is in the middle column. Each figure on the right and left column represents a tram moving along the line.

For instance tram #49 is at the stop called "Ooppera" or it has just passed it. The black figure 0 on the right denotes that the tram #49 is in schedule.

Tram #41 is at the stop called "Senaatintori" or just passed it. The red figure +1 on the right denotes that the tram #41 is about one minute ahead the schedule

Tram #145 is at the stop called "Ylioppilastalo" or just passed it. The blue figure -1 on the right shows that the tram #145 is about one minute late from its schedule.

The system works automatically; The only task for the driver is to log in the system once in the morning

Vehicle computer C90 and the keyboard are 
on the left and the display is on the right just in front of the bus driver


Driver display of tram #44. The distance to the next stop, 'Aleksanterinkatu' is 145 meters. The   message "Myöhässä tells that the tram is -1:20 minutes late from the schedule.

Monitoring screen of the vehicle location. Look at the legend on the left
 

Real-time passenger information provides passenger waiting at bus stops with real-time displays showing the time in minutes when the next bus arrive. Besides this the operator can send an information message to the display if some disturbs of the bus traffic are found.

The forecasts of the expected arrival time of the bus to the stop can be found also on Internet. First the user picks the right bus stop from the list and then after few seconds he or she can see, how many minutes it takes until the next bus and even the following bus arrive to the stop. The same information will be available also in mobile telephone. However, Internet and mobile telephone applications are not yet used in Helsinki although the former is already available for the staff of the City of Helsinki on city intranet.

 

In-vehicle display tells the name of the next bus stop (above)

The approach time of the next bus to the stop can be soon checked from Internet or mobile telephone (on the right)

 

Priority request from the bus is sent direct to the antenna on the roof of the traffic signal controller

Traffic Signal Priority is based on the request of the approaching bus sent via radio modem direct to the next junction. The first message is sent 150-250 meters before the junction. According to the stage of the signal cycle the message is received, signal controller either calls or extends the green for buses. In complex junctions even a special bus stage can be called during the signal sequence.

The second message is sent just after the stop line as an indication that the bus has passed signals and the green for bus can be terminated. The signal priority is not given to buses which are ahead their time-table.

Communication network

The communication of the system is based on the city-owned radio network. Three base stations are located on high chimneys in different parts of the city. The total number of frequencies used for the radio network is six: three for polling buses, one for signal priority, one for updating visual displays on bus and tram stops and one for the data maintenance at depots during nights. Three hundreds vehicles can be polled simultaneously in the network.

All buses and trams are instrumented with an on-board computer and radio modem. Visual displays at bus and tram stops and signal controller equipment are provided with radio modems.  No extra cabling is needed at traffic signal junctions, either, because an unnoticeable plate antenna is located on the roof of the signal controller cabinet.

Thus all of the communication of the system relies on the radio network. This is a great advantage compared to the cable bounded systems. The system is cheaper because no civil engineering works are needed. Only the data transmission between base stations and central work stations is realized via cable network.

 
Manufacturers and investments

The most significant equipment of the HeLMi-system - in-board computers, radio communication, interface to the signal controller and the software -  is delivered by the Swedish company Thoreb-IT Mobile. The radio modems are from the Finnish company Satel. The radio antenna system  is planned by Completech, Espoo.  All displays in the vehicle and at bus and tram stops with the software are from the Finnish company Mitron. The Finnish company Ajodata is the local project manager in Helsinki.
     The total costs of the system are 0.9 Mecu. This comprises the radio network, in-board computers for 20 buses and 24 trams, visual displays for 15 stops and all the installations. The costs of the staff of the Helsinki City Transport (HKL) and the Traffic Planning Division are not included.

Next steps

The effects of the HELMI system to trams and buses were monitored thoroughly using before-after studies. These included journey-time and delay measurements and passenger surveys. The results were very positive and gave the indication to enlarge the system to several other bus and tram lines.

In the beginning of the year 2003 HELMI system includes almost all the tram lines and 2 main bus lines (16 and 23) in then center area of the city. During the year 2003 two more bus lines 14 and 18 will be added to HELMI system, too.