Back in the December 2009 issue of FOCUS, correspondent Shaun Connors described his impressions of driving a London Routemaster double-deck bus. In the supporting global bus article, yours truly provided some historical and technical background on the vehicle.
To recap, the Routemaster was developed by AEC Limited during the 1950s and entered revenue service in London during 1959. Despite its entirely conventional exterior appearance, it featured several technical advances for its era, including full integral aluminium construction, independent front suspension, fully automatic Wilson transmission, power steering, and power-hydraulic braking.
The original Routemaster had an incredibly long service life, only being officially withdrawn from regular London service on December 9th, 2005, by which time many had been re-engined with more modern Iveco, Scania or Cummins power units, and were being operated by independent operators after the privatisation of London’s bus services began in 1984. Since then, several efforts have been made to develop a replacement design incorporating the features which made the Routemaster so successful in the city for which it was expressly intended. At the time of writing, this process was still ongoing, and prototypes of a new design are expected to commence testing during 2011.
Meanwhile, in the Slovakian town of Levoèa, a company called Troliga Bus, which manufactures buses for urban and intercity operation, has come up with what it describes as a “retro-styled” double-decker. Named “Sirius”, this 10,5 metre 68-seater design exhibits definite echoes of Routemaster external appearance, although in a thoroughly modern context. Dual doorways are provided, with the front entrance immediately behind the front axle, and the second side door just forward of the rear nearside corner. Visual material on the Troliga website illustrates the Sirius in left-hand-drive form, with the rearwards-ascending staircase situated over the offside rear wheel. The driver’s cab appears to be separated from the lower saloon by a full-width bulkhead, ruling out any possibility of one-man operation, which is most unusual in modern-day urban bus designs.
No details of construction methods or materials are provided on the website, but the layout suggests fully integral chassisless construction. Power is provided by a Euro 5-compliant Cummins ISBe280 diesel, developing 205 kW (280 hp), driving the ZF AV 132/87 portal rear axle through a ZF Ecomat 6HP 504C 6-speed fully automatic transmission. Retardation is provided by a Knorr dual-circuit full air system with disc brakes all round, assisted by ABS/ASR and an integrated transmission retarder. Independent front axle suspension is paired with airbags for the rear axle, the wheelbase dimension is given as 5 835 mm, and overall width as 2 500 mm. Interestingly, the quoted overall height of 4 200 mm is well within South African legislative limits for “normal” commercial vehicles, and considerably lower than the local limit of 4,65 metres for double-deck buses.
London’s efforts to find a new Routemaster have not been without political criticism and have been described as outright indulgent in some quarters. However, Troliga’s decision to develop and commercially market a design that is conceptually very similar to the Routemaster, with a front-mounted engine and a layout that is clearly limited to two-man operation, begs attention. It seems to suggest that other cities might also find this solution attractive, particularly in densely trafficked central districts. It is not evident, at this stage, whether the Sirius design could be adapted to RHD operation, but, if this were possible, London could find itself with a commercially available Routemaster successor at a more reasonable price than some limited volume special design. We will watch the development of this product with interest!