Dual-mode bus
A duo - bus, bus or even bimodal english dual-mode bus called, is a combination between a trolley and a bus or coach. The duo bus has - like a trolley with an additional internal combustion engine auxiliary drive or battery powered - two independent drives. This allows it to run well off the overhead line infrastructure. In contrast to the low-power auxiliary engine at ordinary Oberleitungsbussen the second drive acts at Duo - buses as a full alternative to similarly sized engine performance. Mostly it is next to the electric motor to a diesel engine with its own powertrain, sometimes by a diesel-electric drive without its own drive train. Since Duo buses do not carry the electrical energy itself, are, according to the UN definition not to hybrid buses. Depending on the operating mode they are subject to either the legal regulations for trolleybuses - or those for buses and coaches.
Prehistory
As an early precursor to the duo - bus, the All Service Vehicle in New Jersey and the two cars in Basel, Lucerne, Oldenburg and Tétouan apply. They have not yet been referred to as dual-powered bus.
Battery-powered duo - buses in Esslingen
When trolleybus Esslingen am Neckar experimented from 1975 with trolleybuses with additional battery power that were first described as a duo bus. The project was a direct result of the oil crisis of 1973, and goes back to an initiative of the then Federal Minister for Research and Technology, the Esslinger SPD deputies Dr. Volker Hauff. He promoted the development of the Duo - bus and struck Esslingen for a reference before operating.
The traction motors of the duo - buses were fed in the catenary- free operation as in a classical battery bus of an accumulator. This so-called traction battery is charged, once again there was a catenary available. Overall charge of the trial Daimler -Benz was existed as three vehicles, including a OE 302 and two O 305 B / E. In 1981, the experiment was terminated, however, with the battery-powered vehicles again. The batteries only had a short service life of 15 months and also proved to be maintenance-intensive. The maintenance costs were a half times as high, the investment costs were 90 percent higher than comparable diesel buses.
Duo - buses with diesel drive
Duo - buses with diesel engines also came first in Esslingen am Neckar used, which first went into operation in 1979. After the failure of the technology of battery-powered duo - buses only the concept of diesel-powered duo - buses there was continued. Later, other manufacturers and networks followed suit.
Benefits
With its catenary independent secondary drive duo - buses with the same speed as can drive in electric mode and cover longer distances as easily, that is, with the same range as conventional buses. Usually Duo buses operate this change trains lines are electrified discontinuous. Some companies use them as a versatile reserve vehicles, which can replace both trolleybuses and diesel buses.
The duo bus can thus use on upgraded and equipped with overhead line routes and in city centers, the advantages of the electric drive - that is, high acceleration, no exhaust emissions and low noise - while it can flexibly operate almost any routes on the outskirts and in the suburbs. In addition, the overhead line network can be set up gradually.
Another benefit is redundancy, that is, in case of failure of the electrical system from damage to pantographs or power failure could be driven. It can also be extended shortly trolleybus lines go where no overhead wires could be laid.
Disadvantages
The concept of the Duo - buses with diesel engines meet the expectations originally provided only limited. A particular problem is ( as with the battery - powered duo - buses ), the high vehicle weight - caused by the entrainment of alternative drive modules - and the increased energy consumption associated with it. Thus, in type Mercedes -Benz O 405 GTD alone weighs six tonnes of electrical equipment.
Also a negative impact on the profitability of duo - buses cause the high initial cost, the more expensive maintenance and the associated higher failure rate of these special vehicles. In contrast, the lifetime is shorter than that of a pure trolleybus. Further disadvantage is the higher space requirement of technical equipment - which in turn sometimes leads to a lower transport capacity and thus also goes at the expense of profitability. Another drawback: each change type of traction is connected to a forced stay, this is at the expense of the orbital period.
Use plants
Currently come Duo trolley buses at Freiburg (since 1987) and the trolleybus Boston (since 2004 ) are used. Earlier duo bus - use operations were:
- Trolleybus Esslingen am Neckar (1979 to 2008)
- Trolleybus Nancy (1982 to 1999)
- St. Etienne ( 1982-2000 )
- Essen Transport Ltd. (1983 to 1995)
- Grenoble (1984 to 1999)
- Seattle (1990 to 2005)
- Trolleybus Kapfenberg (1992 to 2002)
- Trolleybus mountains (1992 to 2010)
- Trolleybus Potsdam (1993 to 1995)
- Copenhagen ( 1993-1998 )
- Arnhem trolleybus (1993 to 2012)
- Trolleybus Zurich (1997 to 1999)
- Trolleybus Lausanne (2002 to 2005)
Due to technical problems many duo - buses were retired early or converted to pure trolleybuses or to pure diesel buses. Some of these tags were made as part of sales, especially because many previous owners had not coped with the complicated technology or they are not required.
Type overview
Standard Duo 438 buses have been built (without the three battery - powered cars Esslinger and the above-mentioned early precursor ), including - with the exception of three prototypes exclusively Gelenkwagen: