An Arriva London Volvo B5LH
|Body and chassis|
|Doors||Single door/Dual door|
|Floor type||Low floor|
|Transmission||Volvo I-shift 12-speed auto|
|Length||10.5m (Early version: 10.4m)|
The Volvo B5LH (initially known as the Volvo B5L Hybrid, also known as the Volvo BRLH) is a hybrid electric bus built by Volvo since 2008. First entered service in London, the B5LH is the only current double decker type in service in the UK that uses a parallel hybrid drive system.
Design and Performance
The B5LH is powered by Volvo's in-house parallel hybrid drive train that couple its I-SAM motor to a 5-litre D5-series diesel engine. The drive train is connected to the Volvo I-shift automatic transmission that drives the rear axle. The whole drive train is mounted in-line at the left rear of the chassis, similar to the B7L. A lithium battery pack is mounted just behind the front left wheel, powering the I-SAM motor system.
The B5LH features stop-start system that allows its engine to cut off when the bus is stationary, and the battery is sufficiently charged. It is also capable to drive at full electric model from standstill to up to 20 kph. In service, Volvo claims that the B5LH achieves 35% improvement on fuel consumption and reduces the emission of green house gases, including carbon dioxide by an equivalent amount.  In service data in London shows that the B5LH is demonstrating between 25 to 40% of fuel consumption improvement. 
Initially, Wrightbus has been the solitary body supplier of the chassis. The pre-production batch were bodied on Eclipse Gemini bodywork, and production chassis to date received Eclipse Gemini 2 body. Currently a lighter Gemini 3 bodywork is offered to the Euro 6 version of the chassis. Alexander Dennis (ADL) is also offering its Enviro 400 bodywork to the chassis, following an order from Stagecoach in early 2014. 
The B5LH chassis is also used as the basis of Volvo's integral 7900H hybrid citybus.
The first batch of six pre-production B5LHs entered service with Arriva London in 2009. Following successful trial, Arriva has followed up with further orders for its operations in London, Merseyside, North East, Yorkshire and Kent. With 259 examples, it is currently the largest operator of the type.
The B5LH has gained increasing popularity with other operators in the UK, with Go-Ahead London, Metroline, London Sovereign and, from Q2 2014, Stagecoach London operating the type in London. Outside the capital, the B5LH is also bought by First, National Express West Midlands, Go Ahead Group, Preston Bus and a number of smaller operators. In many cases, a number of operators are operating the B5LHs alongside its main rival, the serial hybrid drive ADL Enviro 400H.
In March 2014, Volvo also secured a landmark order of the type with Stagecoach for use on its Tayside operations. This batch of 18 buses will be, for the first time, bodied by ADL.
As of April 2014, 434 B5LHs are in service in the UK (1 example has been destroyed by fire in 2013 prior to delivery), with further 73 examples on order or delivery.
Outside the UK, a Euro 6 B5LH demonstrator has been delivered to Dublin Bus in early 2014 for evaluation.
- Allaboutbuses. "World Debut for Volvo Hybrid Double-deck" (4 November 2008) Retrieved 16 Oct 2009.
- Boriswatch. "Hybrid Fuel Consumption – At Last The Truth?" (24 June 2013).
- Stagecoach. "Stagecoach orders new hybrid vehicles for Tayside" (27 March 2014).