|The Enviro400 double-decker.|
Transport for London (TfL) is putting into service 39 new double-decker diesel buses built by Alexander Dennis that are almost 20% more fuel efficient than their predecessors and that meet Euro-4 standards of emissions.
The new Enviro400-model buses, which will be put into operation over the next three months, also generate 18% less carbon dioxide and reduce emissions of oxides of nitrogen by more than 46%.
The Enviro400 models are powered by Cummins 6-cylinder, 24-valve ISBe engines with Selective Catalytic Reduction (SCR) for meeting Euro-4 requirements.
A new High-Pressure Common-Rail fuel system on the engine can deliver up to 1600 bar injection pressures. Injection pressure can be virtually constant at all speeds, realizing greater flexibility and precision in controlling both injection rates and timing.
The new High-Pressure Common-Rail fuel system is fully integrated with Cummins high-precision electronic management system, driven by an upgraded ECM (Electronic Control Module) with a processing speed over twice as fast as the previous ECM. The ISBe engine management system continually maintains an optimum balance between load demands, fuel-efficiency and emissions control.
More than 60% of the current London bus fleet meets Euro-3 emissions standards with the remainder achieving Euro-2 standards.
All Euro-2 and Euro-3 buses have been fitted with particulate filters, which reduce emissions of fine particles, carbon monoxide and hydrocarbons from the vehicle exhaust by more than 90%.