Details of Cars

SOR BN 12: the Czech low-entry city bus with a hump

SOR

SOR BN 12 at Libchavy
SOR BN 12 at Libchavy, the home of the maker. Photo by Honza Groh (Jagro), CC BY-SA 3.0 via Wikimedia Commons.

The SOR BN 12 is a low-entry single-decker city bus made by the Czech manufacturer SOR Libchavy from 2003 to 2022. It was the first bus from the company with at least part of its floor at low-floor height, and its stepped roofline — known as the hump — became its trademark.

SOR BN 12 at a glance

SOR BN 12 key facts
Maker SOR Libchavy, Czech Republic
Type low-entry single-decker city bus
Production 2003–2022
Layout two axles; rear axle driven; engine and gearbox under the floor at the rear
Low-floor area about two thirds of the bus
Floor height 360 mm in the low-floor section
Doors two, three or four, depending on the operator
Body welded steel frame, steel panels outside, plastic lining inside
Axles front SOR, rear rigid DANA
CNG version SOR BNG 12; Ekobus conversions sold as Ekobus City
Successor SOR NS 12 (city) and SOR ICN 12 (suburban)

The model is described on Czech Wikipedia; the manufacturer comes from the German article on SOR Libchavy. There is no English Wikipedia article on the BN 12.

History of the SOR BN 12

The first low-entry SOR

The BN 12 was the first bus from SOR Libchavy that was at least partly low-floor. About two thirds of the vehicle is low-floor, with the floor 360 mm above the road; the rear section, where the drivetrain is hidden, is reached by two steps. The layout belongs to the low-entry (LE) concept, a bus with a low front edge but a raised rear. On the BN 12 it was combined with a variable roof height, popularly called the hump.

The bus has two axles: the front axle is of SOR make, the rear rigid axle comes from DANA. The engine and gearbox sit under the floor at the rear. The body is welded from steel sections, panelled in steel on the outside and lined with plastic sheeting inside, and the driver works in a closed cab.

SOR BN 12 of Arriva Praha in Modřany
SOR BN 12 of Arriva Praha in Modřany, Prague. Photo by ŠJů, CC BY 4.0 via Wikimedia Commons.

Production and operation

Thanks to its favourable price the BN 12 spread quickly to many small and medium-sized Czech towns. Among the operators were Chrudim, Kolín, Louny and Hodonín, and the bus also ran in Liberec and Havířov; a few examples were used in Prague by Veolia Transport and by the city transport company. The type was exported to Slovakia as well, for example to Trnava.

SOR offered the bus with two, three or four doors, so the same type could serve different kinds of operation. In 2004 production began of the SOR CN 12, a two-door version for intercity and suburban service with a different type of seating. From 2006 the company also built the fully low-floor SOR NB 12 alongside the BN 12, but the older model was not dropped: because the two buses differed greatly in concept and price, the BN 12 and CN 12 stayed in the programme until 2022, when they were replaced by the SOR NS 12 city bus and the SOR ICN 12 suburban bus.

Natural gas versions

The shape of the body made the BN 12 popular for conversion to compressed natural gas. The hump on the roof is a convenient place for the gas cylinders, which are otherwise difficult to fit without losing space or spoiling the look of the bus. The first conversions were carried out by the company Ekobus; these buses, later called Ekobus City, used Cummins Westport engines with fully electronically controlled fuel injection. Later SOR offered its own factory CNG version, the SOR BNG 12, also with Cummins Westport engines. Buses meeting the Euro 5 and Euro 6 emission standards used an Iveco Tector engine.

Design and features

  • Low entry: about two thirds of the bus is low-floor, with the floor at 360 mm in that section.
  • Roof hump: the variable roof height gives the BN 12 its unmistakable profile and makes room for gas cylinders.
  • Steel body: a welded frame of steel sections with steel outer panels and a plastic lining inside.
  • Door choice: two-, three- and four-door versions for city, suburban and intercity work.
  • Factory gas option: the BNG 12 was available new with CNG drive, not only as a conversion.
SOR BN 12 in Osnice
SOR BN 12 in Osnice, Central Bohemia. Photo by ŠJů, CC BY 4.0 via Wikimedia Commons.

SOR BN 12 versions

  • BN 12: the standard diesel city bus, offered with two, three or four doors.
  • CN 12: the two-door intercity and suburban version introduced in 2004, with different seating.
  • Ekobus City: a CNG conversion by Ekobus with Cummins Westport engines.
  • BNG 12: the factory-built natural gas version, also with Cummins Westport engines.
  • Euro 5 and Euro 6 buses: later examples with the Iveco Tector engine.

The BN 12 was the starting point for the two-door SOR CN 12 and was built alongside the fully low-floor SOR NB 12. More vehicles from this Czech maker are in the SOR collection, and longer reads are on the Articles page.

Sources