Bus World Record

My second blog from Bus World in Kortrijk will deal with the performance of the Volvo hybrid buses.

For the first time we could report on the fuel consumption from the real traffic of the Volvo double decker hybrids (B5TL) that run in London. The six buses have now been in service for more than three months. The fuel consumption has gradually improved during the run-in period. We now read 44 litre per 100 km. They are all in service on rout 141, the second slowest rout in London, running with an average speed of 10.3 km/h. During rush hours the speed is 7.8 km/h and in the nights it can approach 15 km/h. The fuel consumption improvement relative the B9TL (2009 model) with Eco gear programme is 35.5%.

The Volvo 7700 hybrid that is in service in Göteborg has also gradually decreased the fuel consumption from 28 litre per 100 km, as reported at the UITP congress in Vienna, to 26 litre per 100 km the last month. This gives more than 30% fuel consumption decrease relative the 7700 (2009 years model with Eco gear box programme). In Gothenburg the traffic is varied on four different routs similar to the traffic in most European cities.

The projects has performed much better than targeted.


Next to the hybrid bus and the test drive and test ride the drivetrain, that we call I-SAM, was an attraction of the Volvo stand, here in the centre of attraction in the centre of the picture.

The in-house design and determination not to compromise the fuel consumption has led to a development of some new key components. The intimate interaction of engine, gear box, energy storage and power consumers has been possible due to the full access to all interfaces. The following major contributions ad up to the total improvement:

1, Brake energy recuperation

2, Stop & go (the engine turns of at bus stops and idle)

3, Utilising the I-Shift gear box (the 12 gears and low losses brings another 6%)

4, Electrification of auxiliaries (Air conditioner, compressed air for breaks etc., steering servo, door actuators)

The relative contribution varies depending on the traffic situation an number of passengers, but the experience from demonstrations in more than 20 cities converge to savings of 25-35%. I.e. the construction is very robust and less dependent of traffic pattern and topography. The driver behaviour is interesting, in all tests except one, we have seen very few discrepancies between drivers. Even if driver training improves the fuel consumption, also without training we find less impact compared to non hybrids.

In the economical crisis the improvements are most welcome for the operators. Immediate shortage of money and difficulties to get loans however makes financial support for the initial investments urgent all over Europe.

About volvobuses

Adjunct Professor of Catalysis at Chalmers University of Technology. Lives in Gothenburg, Sweden, with my wife and three daughters born in 1991, 1994 and 1997. Is a passionate runner.
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