Quietly, the bus docks at the stop and takes a “snack” while passengers hop on and off. An articulated arm above the roof stretches up and inserts itself into a suspended rail above the vehicle. In about 20 seconds, the bus batteries are recharged.
Described as “bottle-feeding,” these flash refills made by the TOSA bus at certain stops no longer surprise the regular passengers of bus line 23, linking the Geneva airport to the most populated municipalities on the outskirts of the Swiss city. The vehicle, operational since late 2017, began its life as a prototype born from the collaboration between three parastatal city organizations and a private company.
The idea came about at the beginning of the decade, during a meal that brought together the then-director of Public Transport of Geneva (TPG) and his counterpart at ABB Sécheron, a local subsidiary of the Swiss-Swedish industrial group. GIS (the electricity supplier) and the Office for the Promotion of Industries later joined the adventure. Together their initials formed the acronym TOSA.
Its originality? "In this partnership, the TPGs have been customers from the outset," recalls Thierry Wagenknecht, technical director of the publicly run system, “In a context of energy transition, we turned away from trolleybuses, whose level of maturity suggested weak development over the long term. We have opted for an electric bus that offers the same possibilities as diesel, as jnterrupting service during the day to recharge the vehicle was out of the question. For financial reasons, we could not afford to hire someone just to supervise the operation, so we required that the batteries last 10 years on a bus that lasts 20 years. The result is unique: a bus that recharges at the depot, in a few minutes at each terminus and, if necessary, in a few seconds at the stops.”
The TOSA bus can be recognized by the large size of its passenger compartments, provided by the German-speaking Swiss manufacturer Hess. The Geneva models with single joints are 18 meters long and can carry up to 110 passengers, while those that the French city of Nantes has commissioned (and expects to operate next autumn) are bi-articulated, 24 meters long and have a capacity of more than 150 passengers.
Complemented by longer recharges at terminals and depots, short power injections at certain stops allow the vehicle to run for a full day, without stopping, and without the dense overhead cable network that supplies energy to trolleybuses. Maintaining the batteries charged guarantees their longevity and limits their weight and volume, to the benefit of the payload — in other words, the passengers.
Geneva’s TOSA bus developed quickly. A prototype was presented in spring 2013, a year and a half after the project first started. But the commissioning of an entire line in December 2017 was not without bumps, preceded by ABB's announcement of a partial relocation of its activities to Poland, which has now been delayed. The TPGs have, experienced malfunctions in the battery cooling system, whistling sounds during recharges, and overly flexible brackets supporting the charging rails.
As the first external customer, Nantes should benefit from the experiences of the buses’ hometown city, but the French city’s long version (which will replace shorter, gas-run buses on a saturated line) will be a first in Europe. The capital of the Pays de la Loire region made its choice after an open call for tenders. "We needed a bus that could be recharged en route," explains Bertrand Affilé, Vice-President of Nantes Métropole. “The flash technology convinced the commission and the operator. It seemed more reliable to us: loading from above implies fewer hazards or vandalism risks than ground-level power supply." The TOSA’s XL version could in turn entice Geneva into operating a new line by late 2022.
The troubles on the existing line have been solved. "In March, 98 percent of this line was covered by TOSA buses, which have covered more than 500,000 km since they were put into service," says Thierry Wagenknecht. “Compared to a thermal engine, we save 1,000 tonnes of CO2 per year. A TOSA bus is 25 percent more expensive than a diesel one, but 12 percent cheaper than a trolleybus, according to our initial estimates. »
Will the TOSA bus convince others? ABB says there are talks of an agreement with an Asian city, while Hess reveals that there are negotiations with other French and Australian cities.
This article is being published as part of Earth Beats, an international and collaborative initiative gathering 18 news media outlets from around the world to focus on solutions to waste and pollution.
