FRANK BEETON reports on a new take of a four-year-old theme in the London bus sphere.
Back in 2011, we reported on the reveal of London’s New Routemaster double-deck bus design. Built by the Northern Ireland-based Wrightbus organisation, this bus combined elements of proposals submitted by sports car manufacturer Aston Martin, as well as bus, coach and truck designers, Capoco Design.
The finalised layout, included overall dimensions of 11,2 x 2,55 x 4,4 m, with a seating capacity of 62, and provision for 25 standing passengers plus one wheelchair bay. The three entrances were positioned at the extreme front (opposite the driver), immediately behind the set-back front axle and at the rear nearside corner.
These were complemented by two staircases leading to the upper deck; one opposite the central entrance, and the other in the traditional rear offside corner position.
The technical specification included a diesel-electric hybrid drive system, made up of a high-performance, low-emission diesel engine driving a generator to charge a lithium-phosphate battery pack, a regenerative energy-recovering braking system, and electric drive wheel motors.
The first of these buses entered service in February 2012 and, to date, deliveries and orders have totalled 1 000 units. They have been spread across several London operators, and have reportedly been well-received by the travelling public.
New Routemasters have not been without fault, however, with the most significant being battery unreliability, which has led to excessive reliance on the diesel engine and increased emission levels.
However, the design philosophy, while establishing itself as an iconic presence on London’s streets, has argued against flexibility in layout or specification, and Transport for London subsequently issued a requirement for a generally similar vehicle, but with shorter overall length, two doors, a single staircase and an alternative driveline configuration.
Not wishing to lose its prominent position as a supplier of buses to London, Wrightbus, in conjunction with Volvo Bus, moved swiftly to develop an alternative design, dubbed SRM, to meet these requirements.
Unlike the fully integral New Routemaster, the SRM is 10,6-m long and is built on a Volvo B5LH Euro-6
hybrid chassis. The B5LH is powered by Volvo’s I-Sam parallel hybrid system utilising a D5K five-litre Euro-6 180 kW (240 hp) diesel engine, 120 kW (160 hp) electric motor and 12-speed I-Shift automated transmission.
The SRM closely follows the New Routemaster design in terms of exterior appearance, and makes maximum use of common components. Passenger capacity has been set at 87 all up, including 21 standees, providing four more seats than the New Routemaster.
An initial order for six units was placed by RATP Dev-owned operator London United, and these buses will enter service in September on route 13 from Golders Green to Aldwych. It is intended that the SRM/Volvo B5LH combination will also be made available to operators located outside London.
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