Dr Rainer Müller Technical Director,Verkehrs-Aktiengesellschaft Nürnberg
GHOST TRAINS are now appearing on the tracks of the Nürnberg metro, gliding silently under the city centre at dead of night. Last month saw the start of test running on the first section of automated metro line U3, which is scheduled to open for revenue service in February 2006.
Getting the two prototype DT3 units onto the network marks a significant landmark in the Rubin programme to develop Germany's first fully-automated metro line. The project was launched by VAG and Siemens in October 2001 (MR02 p11) following an earlier feasibility study. Siemens is main contractor for both the new trains and the automation equipment.
In fact, the first married-pair EMU 701+702 had already been hard at work on the 800m test track alongside VAG's Langwasser depot. This has been equipped for automatic operation, with four 'virtual stations' at which the train calls. The prototype was delivered to Nürnberg in April and, following commissioning and initial trials, was formally approved for automatic operation by the regional safety authority at the end of October. The second unit was delivered in early November, and was due to join its fellow on the main line in January.
Testing has initially started on the 950&nbps;m northern section of Line U3 between Maxfeld and the junction with the existing north-south Line U2 at Rathenauplatz. The test programme has two more stages, so that by mid-2005 automatic trial running will be in full swing over the whole route, building up to the start of revenue service next year.
The first phase of Line U3 runs for 6·1 km between Maxfeld and Gustav-Adolf-Strasse in the southwest. Over the 3·5 km between Rathenauplatz and Rothenburger Strasse the trains will share tracks with U2. In this first phase, U3 trains will serve nine stations, of which six are on the common section.
By 2012, Line U3 is due to be extended to a total length of 11·6 km with 16 stations. The northern branch will be continued from Maxfeld to Nordwestring, adding four more stations. The first two at Kaulbachplatz and Friedrich-Ebert-Platz are due to open in 2009.
The southern branch is to be extended to Gebersdorf by 2012, although VAG and the city government are currently reviewing the proposals and timescale. Development in the southwest has not progressed as fast as anticipated, and there are questions over the city's ability to fund the extension.
A further extension of U3 from Gebersdorf to Oberasbach and Zirndorf in Fürth would be dependent on the willingness of that town's authority to fund the work. Fürth is currently extending Line U1 to Kieselbühl. The initial 960 m from Stadthalle to Klinikum was opened on December 4 (RG 1.05 p14), and another 910 m to Hardhöhe will follow in 2006, but no schedule has been set for building the final 660 m.
Good timing
Nürnberg's role as the pioneer of fully-automatic operation in Germany is the result of fortuitous timing. When the decision to build U3 was taken, it was recognised that some form of automation would be needed to dovetail U3 and U2 services over the busy city-centre section. And replacements for the oldest batch of trains, which entered service in 1972, would need to be ordered at the same time as the extra cars to operate U3 and the extension in Fürth.
Automatic operation will initially start on Line U3, using 16 of the Wien-built DT3 sets. The technology will then be extended to Line U2 in 2007 as the replacement rolling stock comes on stream. Having both routes automated will enable VAG to maximise the efficiency of the city-centre operation.
However, the timing for conversion of U2 means that equipment has to be designed to operate in mixed mode for the intervening 18 months, with automatic trains on U3 interworking with manually-driven trains on U2. Thus Rubin is pioneering a step-by-step conversion process which is likely to be of value to other metro operators planning to automate existing lines.
Total cost of the project is currently put at €315m, which is being shared by the city, the federal government and the Land of Bayern. Of this total, €115m relates to the construction of the two new sections of U3, funded 85% by the government and Land, and 15% by the city. The 30 new DT3 trainsets account for €110m, of which 50% will come from Bayern and 50% from VAG itself. The automation equipment for the two routes adds a further €90m, and here the government and Land are contributing 87·5% of the cost, and the city 12·5%.
Construction of the U3 extensions to Nordwestring and Gerbersdorf will add a further €235m in civil engineering costs, €20m for automation equipment and €:30m for seven more trainsets. There are options in the Siemens contract for two, two and three extra units to be exercised as each extension takes shape. Bids for the E&M works on the Maxfeld - Friedrich-Ebert-Platz section are expected to be called in April.
Although the capital costs of automation are higher, VAG predicts significant savings in operating costs. Optimised driving performance is expected to cut energy consumption, turn-back times can be shorter, and no additional staff will be required to operate the new line. We expect the savings to cover the cost of the automation equipment after about 10 years.
Automation overlay
Core of the automation system is the communications-based train control equipment. The on-board computers will communicate with their counterparts at the Operations Control Centre via a 1200 baud continuous data transmission system, using inductive loops laid between the rails. Each train is provided with two pairs of transmitting and receiving antennae. Track-to-train messages use a 36 kHz frequency, whilst the return signal uses 56 kHz.
The lineside ATC computers use a two-from-three voting protocol for vital processing. They take track occupancy and routing data from the interlockings. Further data comes from the train, including the train identity number, formation (two or four-car), direction of travel, vehicle status and location. Data is also received from the platform track monitoring system at each station.
Based on all this data, the ATC calculates movement commands which are sent to the on-board ATO and ATP computers. The ATC can also issue emergency stop instructions. The automation equipment is designed as a separate overlay to the lineside signalling. This will allow the ATC to work with both conventional relay interlockings on the existing sections of U2 and with new solid-state interlockings on U3.
The on-board ATO accelerates and brakes the train to suit the line speed limits, opens and closes the doors on the correct side at stations, and manages the operation of the train in accordance with the preset timetable data and messages from the lineside ATC. The separate ATP oversees all aspects of the operation, and can over-ride the ATO if necessary.
Before each DT3 trainset enters service, the on-board computers undertake a full self-diagnostic health check and report the train status to the OCC. The unit is then given instructions about its route and timetable diagram, before being dispatched from the stabling sidings to enter service.
Each DT3 car is also provided with a concealed control panel, so that the trains can be manually driven when necessary. Manual driving will also be needed to transfer the trains to and from the main depot and workshop at Langwasser for servicing. This depot is located near the southern end of Line U1, which will not be equipped for ATO.
CCTV cameras are being provided at all stations and inside each car, so that OCC staff can monitor what is happening and intervene where necessary. The OCC is also provided with vehicle status displays, and diagnostic information is transferred automatically to the workshops, where maintenance staff can interrogate the on-board equipment and reset many failures remotely without the need for manual intervention.
Platform track monitoring
Mirroring the Maggaly technology used on Lyon Line D - which provided the inspiration for Rubin - VAG has opted not to use platform screen doors. Instead, the track areas at each station will be continuously monitored by a high-frequency detection system which is currently under test at W”hrder Wiese on the common section of lines U2/U3.
The 24 GHz transmitters are located below the edge of the platform, and the matching receivers are mounted along the tunnel wall, above the height of the third rail. These scan the whole of the track area up to platform level. There are 16 transmitters on each strip, spaced at 150 mm intervals. If an object intrudes into the space and breaks two adjacent beams, an alarm is triggered.
The detection system measures the length of any obstruction by counting the number of beams broken. Anything longer than 2m is deemed to be a train, and no alarm is issued. If one transmitter fails, the fact is automatically reported to OCC, and until it is reset, an obstruction cutting one beam to either side of the fault will activate the alarm.
Separate modules are installed at the mid-point of the platform to detect anything falling between the coupled units of a four-car train. They are mounted at a lower level, with the transmitter in the track by the offside rail, and only activated while the train is stationary.
The detector control system is built around a redundant solid-state processor unit, located in the station equipment room, where detailed beam-by-beam indications are provided for maintenance purposes. These are not repeated in the OCC, where a simple alarm will alert the staff to check for an obstruction using the CCTV monitors.
The ATC's response to an alarm varies by the location of the obstruction. If someone or something falls onto the track behind a train in the platform, it can still depart. An object detected in front of the train will trigger a full emergency brake application, but traction power is not cut off automatically.
End detector modules are also provided to protect against any intrusion into the running tunnels. Short barrier screens protect the first few metres of the tunnel walkway beyond the platform, and access is prevented by locked gates. The locks are monitored remotely, and unauthorised entry will trigger an alarm. Maintenance staff wishing to enter the tunnel must contact the OCC first to de-activate the locks. To permit an emergency exit, the gates can be opened from the tunnel side without triggering the alarm. If there is an interlocking room at the station, two sets of gates are provided so that maintenance staff can reach the interlocking room without disturbing the OCC.
Eight CCTV cameras are provided at each station to monitor both platform tracks. One camera is located 10 m inside the running tunnel behind each of the four portals, and a second is mounted 25 m further into the tunnel to monitor the approach tracks. If an alarm is triggered, the CCTV images for a short period before and after the incident are recorded for analysis. The OCC will check the situation using the CCTV monitors, and if no obstruction is seen the incident will be deemed to be a false alarm.
Roving staff
Although both U2 and U3 will be fully automated, there will still be an extensive human presence around the network. VAG agreed with the railway unions that at least one-third of the train drivers made redundant by the conversion of Line U2 would be re-deployed as Customer & Service Assistants (CUS). On average, there will be one CUS for every three stations at all times the metro is operating.
The CUSs will provide information to passengers on routes, timetables and fares. They will also improve the perception of safety by helping to police the stations and trains against vandalism and petty crime. Unlike the present drivers, who must remain in their cabs and are therefore unable to deal with incidents without halting the trains, CUSs will be free to roam the network as required.
The CUSs will be able to respond rapidly to minor failures of station equipment such as ticket machines or passenger information systems, and help to keep the metro functioning efficiently. There will also be a small technical support team for back-up and dealing with more major incidents.
At present, VAG employs 148 drivers on Lines U1 and U2, together with 44 staff in the main control room. Were Line U3 to be equipped for conventional operation, this would have increased to 218 drivers and 56 control room staff. Thanks to Rubin, the network will only need 94 drivers for U1, 38 CUSs for U2/U3 and 47 control room staff. This is a saving of 95 posts over the total that would have been needed, but only a net saving of 13 on the current requirement.
Effectively, Rubin means that VAG can add a third line to its network without recruiting extra staff. However, in practice it will not be so straightforward as the period of mixed operation pending the conversion of U2 means that there will be a short-term bulge in staffing during the transition. Reflecting German employment legislation, the reduction in staff levels will be met through natural wastage rather than compulsory redundancy.
A new job profile for the CUSs is now being drawn up, together with a conversion course. This will make use of simulator training to equip the staff to deal with a wide variety of incidents. There will also be regular refresher courses for these front-line staff, who will increasingly be seen as the public image of the metro network.
- CAPTION: Now on test at Langwasser, the first DT3 trainset has a similar interior to VAG's existing stock. Large end windows and a wide inter-car gangway give an open ambience
- CAPTION: The automated trainsets are being equipped with very sensitive detector strips on the door edges Photo:VAG/Claus Felix
- CAPTION: CCTV cameras mounted inside the tunnel portals allow control centre staff to monitor the platforms at Wöhrder Wiese
- CAPTION: Locked gates and screens prevent unauthorised access to the running tunnels
- CAPTION: High-frequency beams transmitted from under the platform to receiver strips mounted along the tunnel walls detect any intrusion into the track area (left). Each 150 mm beam shows as a green stripe on the maintenance monitor (above), which turns red for an alarm or blue when a train is detected
- CAPTION: The prototype DT3 set is being used to prove automated operation on the test track at VAG's Langwasser depot
