Combino trams prove successful for Budapest

In Intelligent Transport Issue 3 2006, there was an article about the Combino trams manufactured by Siemens, for operations in Budapest, Hungary. This time, we would like to provide a more detailed description of the trams and to report on the experience over two years of use and the follow up on their commissioning.

Between July 2006 and May 2007, we put into operation 40 modern low-floor trams, each with a length of 54m and a width of 2.4m, with eight 1.3m wide doors on each side. The new trams operate with excellent results along tram lines 4 and 6, which have the highest traffic density and the highest number of passengers in Budapest. Ever since they were put into operation, the trams have been transporting passengers safely and in a passenger- and environmentally-friendly manner. They have already travelled over four million kilometres. On these lines alone, the number of disturbances in traffic dropped to 1/20th after the trams were put into operation.

Public transport within Budapest is provided by BKV Zrt

BKV Zrt, owned by the Municipality of Budapest, provides public transport for 1.6 million inhabitants over an area of 565km2. In 2007, BKV Zrt transported 1.3 billion passengers and its vehicle fleet travelled 5.5 billion passenger kilometres. In 2007, its vehicle fleet – comprising buses, trams, trolley buses, underground and suburban trains – covered 176 million kilometres. In that year BKV Zrt had 12,400 employees, of which nearly 5,000 were vehicle drivers. Over the complete line network, passengers can choose to get on a BKV Zrt vehicle from 4,900 stops. The ratio of public transport to individual transport is 60/40 in Budapest, which is an extremely good figure.

Railbound transport plays a particularly important role in Budapest. Trams, the underground and suburban trains provide 57.5% of the total network capacity. In Budapest, the length of public tram rails is 341.5km, and 334 million people take the tram each year.

Before the Combino trams were put into operation in 2005, BKV Zrt had 720 trams. The fleet still included 160 ‘UV’ type trams that had a small capacity and had been in operation for approximately 50 years. The objective was to scrap the old trams and substitute the low-standard service they provided with more modern equipment, while putting into operation state-of-the-art trams on the line with the largest traffic load in Budapest. Putting the Combinos into operation realised these goals.

BKV Zrt currently has 600 trams with different passenger capacities. In addition to the Combino trams, the fleet consists of KCsV and ICsV trams manufactured in Hungary, T5C5 trams manufactured in Czechoslovakia and TW 6000 trams manufactured in Germany.

The role of Combinos in passenger transport

On an average weekday, the Combino fleet transports a total of 400,000 passengers, which is nearly the same as the daily passenger numbers on Budapest’s M2 underground line, (which is known as the busiest).

The large passenger transport capacity of this line can be characterised by the ability of the 36-strong vehicle Combino fleet to transport 10,600 passengers in one direction within 1 hour. Passenger count figures show that the number of passengers in peak hours exceeds 9,000. It takes 32-35 minutes to travel along the line in one direction, and the trams spend as little time as possible at terminal stations. The shortest headway between trams is 90 seconds, while the longest is seven minutes over the course of the day.

Pest and Buda are separated by the River Danube. Lines 4 and 6 start out from Buda going to Pest, then travel around a 6.5km semi-circle before returning to Buda after crossing the Danube. The line has 40 stops. This tram plays an important part of Budapest’s scene.

The Combinos delivered to Budapest represent a new generation. Beforehand, Siemens AG manufactured 475 Combino trams and sold them to Germany, Switzerland, Poland, Japan and Australia. While previous Combino trams were constructed of aluminium with steel bolts, the structures of the trams for Budapest were made of stainless steel and the bogies were shifted to the centre of the body shell. The bogies have a 4° turning space and folding-in is guaranteed by a hydraulic protection system.

Combinos represent a new quality of service

The trams have a range of benefits which include:

• Platform level entry and exit
• Noise and vibration damping
• Excellent passenger information systems
• Good internal and external looks
• Heating and cooling systems

These characteristics all result in a favourable change in quality for Combino passengers along lines 4 and 6.

Special attention has been paid to ensure that disabled passengers can get on and off the trams easily and can comfortably move and be seated within the vehicle.

Given the rapid increase in energy prices seen recently, the quantity of energy used for traction was appreciated. The tram, equipped with state-of-the-art vehicle control and motors – in collaboration with the renewed power supply and overhead line system – is capable of feeding back 35% of its traction energy into the network for reuse. Essentially, modernisation was about converting the radial power supply system into a parallel system, while the network was strengthened wherever it was required for bottlenecks, thereby making the network capable of receiving the energy provided by back-feed braking mode.

Drivers are provided with a high-comfort workplace with excellent ergonomic surroundings. These favourable working conditions are in place to ensure an extremely high standard of quality in work.

The technological design, reliability of operation and passenger services offered by the Combino trams, has confirmed that the goals of the investment have been achieved.

As a result of the infrastructure investments made at the time, as well as before designing the trams, the track network was changed to eliminate vibrations and to ensure a long lifetime. The power supply and overhead line network was modernised and passenger platforms were remodelled to accommodate the disabled. The maintenance and storage base was also modernised and renovated. This way, a balanced system was created for vehicles and the infrastructure serving the vehicles, which operate as expected and required.

The acceptance and operation of the tram has attracted the interest and recognition of transport experts from several metropolitan cities. Foreign experts regularly inquire and come for professional visits and praise the developments in Budapest.

BKV Zrt specified a new generation of Combinos for Budapest

Following an open international tendering process, BKV Zrt concluded the supply agreement with Combino Budapest Consortium (CBC) headed by Siemens in April 2003. In addition to the obligation to deliver vehicles, the contract obliged CBC to supply documentation, spare parts as well as garage equipment required for vehicle maintenance, as well as to provide training for a two-year period of maintenance for the vehicle supply.

Instead of the vehicles that were previously produced with an ALUGRIP aluminium structure, Budapest purchased trams with a stainless steel structure.

The type marking of the tram is Combino NF12B1 (‘NF’ means low-floor, ‘12’ means the number of axles, and ‘B1’ indicates the sub-variation).

The vehicle designed for Budapest is a further developed variation of the standard Combino family. The vehicle consists of six segments, has a length of 53.99m and width of 2.4m, has a low-floor along its total length which allows for walking the complete length of the tram. It has eight doors with two wings on each side. Floor height is 350mm along the total length, with the entry edge sloping to 320mm at the doors.

The vehicle can accommodate 353 persons calculated with seated passengers and four standing passengers per square meter. It has 64 seats (six of which are folding seats).

Passenger space and interior design

Several large doors had to be built in the tram along both sides, to meet the existing infrastructure characteristics. Considering that passengers approach trams from both ends of the platform, doors were installed directly behind the driver cabin.

In all low-floor vehicles, the bottleneck of passenger flow is the dimension of wheel trucks. In the narrowest cross section of the Combino, the width of the corridor is 720mm. (It is inevitable for low-floor trams to have narrow corridors due to the design of bogies).

The nice shapes and upholstered covers, the vandalism-proof seats, fixed and mobile handrails, the beautiful passenger information equipment and the non-slip floor have earnt the appreciation of passengers.

The vehicle has eight external swinging doors with a free opening of 1,300mm and a free height of 2,100mm on each side, operated by electric motors. Pram and wheelchair users may pass through the two-winged doors without meeting any obstacles (there is no handrail in the middle).

Wheelchairs may pass through the second door from the end of the tram (i.e. doors number 2 and 7). The separate indicator button and handrail, the supplementary threshold and the pictogram installed in the floor provide appropriate services for wheelchair users.

Body shell

The body shell has a self-supporting, light structure made of stainless steel, which is made of prefabricated components and is protected from twisting. The parts for connecting to the bogie and the power inlet connection points at the ends of the trams were made of hard-to-rust carbon steel, as this material absorbs dynamic forces better.

The stainless steel body shell, which carries the load, has an external cover fixed using flexible glue. The cover consists of pre-polished aluminium plates that are easy to replace if damaged, without requiring any locksmith or painting work.

The front components that determine the tram’s looks were made of plastic and are screwed to the steel structure. This also facilitates repairs in case of accidents. The vehicle consists of six modules, with two modules creating one basic mechanical unit.

Driver cabin

The driver’s cabin of the tram satisfies all current requirements and has an excellent ergonomic design with sufficient air conditioning. The cabin offers an excellent view in all directions, and glass surfaces have intensive mist removal. The large external mirrors are heated and may be set in all directions using pushbuttons. If any failure occurs, the driver is informed about the action to be taken in a text message displayed on a large display.

The driver seat may be set in all necessary directions. Any of the tram coaches are fit for driver training – a supplementary seat may be installed for trainers temporarily, and a mobile trainer control board may be plugged in, which allows for imitating failures. Driver awareness is monitored by a built-in system, which intervenes as necessary.

Bogies

Four of the six bogies have traction, and the second bogie from the end of the tram is a free-running bogie. Apart from traction, both types of bogies have the same structure. Springs actually have three grades; the first is the rubber springing the wheels, the second consists of the pairs of rubber springs located on the interior side next to the axle ends. The main spring, which is also the third grade, consists of the spring components made of large rubber hemispheres on both sides of the bogie, which also serve to support the body shell.

All traction bogies have two traction units with flexible suspension, with asynchronous motors arranged longitudinally, which drive the wheels in front of and behind the motors, meaning that a so-called single-side monomotoric traction was installed on both sides of the traction bogie. The advantages of this traction concept include good route tracking and slight transversal floating. The power feed units (pantograph, main switch, etc.) are accommodated in the pantograph container located on top of the running vehicle module.

Auxiliary power supply

Auxiliary power supply consists of two voltage systems. Auxiliary transformers provide 3-phase 0.4 kV voltage for the heating and ventilation equipment and floor heating of passenger space, the ventilation for traction containers and the air conditioning system for the driver cabin, and 24 V DC voltage is provided to other units (track brake, traction and vehicle control, passenger information, etc.).

The air conditioning system for passenger space, which was installed subsequently, has independent power transformers.

Braking system

The trams have the following four independent braking systems:

• Electro-dynamic brakes on the traction bogies
• Passive hydraulic dynamic brakes of traction bogies
• Active hydraulic disk brakes on free-running bogies
• Electro-magnetic track brakes on all bogies

Heating, cooling and ventilation for passenger spaces

The containers which hold the heating, cooling and ventilation equipment are installed on the roof. From here, the processed air flows through the ceiling duct system into passenger space. With intensive machine ventilation, windows that can be opened would not be necessary, but in spite of this, all windows – save for the four windows used to support passenger information signs on the sides of the trams – can be opened by sliding them to one side, as the passengers of Budapest have grown used to. The windows in the passenger space have heat-reflecting tinted glass. In addition to hot air blown in, heating for passenger spaces is provided by floor heating built into twelve fields in the vicinity of doors, which serves primarily to combat icing, which is a consequence of the low-floor level. The electric capacity of air conditioning equipment for the passenger space, which was installed subsequently, is 3×30 kilowatts.