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Mayor’s real record on air pollution is nothing to boast about – Stephen Knight

March 30, 2015 2:27 PM

Stephen Knight AM, Liberal Democrat London Assembly environment spokesperson, commenting on today's announcement confirming that the Ultra Low Emission Zone will go ahead said:

"This announcement is welcome, although I regret that we still have to wait five and half years until the introduction of the Ultra Low Emission Zone. Boris Johnson will have long left City Hall when this scheme finally starts to be implemented.

"However let us be absolutely clear that the Mayor's overall record on tackling air pollution is nothing to boast about.

"There are already other buses available which produce far less dangerous nitrogen dioxide than the New Routemasters.

"The Mayor has admitted that the New Routemaster buses generate five times as much dangerous pollution nitrogen dioxide than at least two existing hybrid buses that are already operating.

"We have always known that the New Routemaster buses were incredibly expensive to purchase and operate. We now know that some of them will be the dirtiest buses on London's roads in 2020.

"For all the rhetoric from the Mayor's office about the New Routemasters having a high environment standard it is clear that alternative buses generate far less dangerous nitrogen dioxide."

"It is simply appalling that the Mayor has locked himself into a contract to continue purchasing New Routemasters with such poor controls on their exhaust emissions."


1. Definition of Euro 6 standard which will apply within the Ultra Low Emission Zone:


2. Past Mayoral Questions asked by Stephen Knight and other London Assembly embers

TfL bus fleet - New vehicles that aren't Euro VI compliant

Question No: 2014/4280

Stephen Knight

Please provide a breakdown by model of all the buses that have entered the TfL fleet since 1st January 2014 that are not Euro VI compliant?

Written response from the Mayor

TfL has brought in Euro VI engine vehicles at the earliest time from which they have been available from respective manufacturers. Virtually all new buses entering the fleet are now of this type to maximise the emission benefits to London. A Euro VI hybrid bus emits 95 per cent less NOx than a fleet average Euro V hybrid vehicle.

TfL has introduced 189 New Routemasters (NRM) with Euro V engines since January. This is because the manufacture of the NRM was awaiting final certification of the Euro VI engine made by Cummins.

It is worth noting that the NRM buses with Euro V engines are the cleanest diesel-electric hybrids of their generation in the bus fleet as their nitrogen oxide (NOx) emissions are 80 per cent lower than a fleet average Euro V hybrid.

New Routemaster bus - Euro VI compliance

Question No: 2014/4281

Stephen Knight

How many New Routemasters will there be in TfL's fleet by the end of 2014 that are not Euro VI compliant?

Written response from the Mayor

TfL expects there to be 306 Euro V and 50 Euro VI New Routemasters(NRM) by the end of the calendar year.

These vehicles will continue to significantly lower the emissions profile of the London buses fleet. A Euro V NRMs emits 80 per cent less nitrogen oxide (NOx) than the average Euro V diesel-electric hybrid, while a Euro VI NRMs emits 95 per cent less NOx than the average Euro V hybrid.

NO2 emissions of Euro VI double decker hybrid bus fleet

Question No: 2014/4283

Stephen Knight

What are the measured exhaust emissions of NO2 of the following Euro VI hybrid diesel-electric double-deck buses that have or are due to enter service with TfL this year: (a) Alexander Dennis E400H, (b) Wrights / Volvo Gemini 3, and (c) New Routemasters?

Written response from the Mayor

The New Routemaster is by far the cleanest hybrid Euro V bus of its generation, compared to other Euro V hybrids in the fleet tested on the independent London Buses route cycle, and is almost as clean as a new standard Euro VI hybrid. The first table provides the comparisons.

Euro VI vehicles are showing better NO2 performance than their Euro V counterparts because they are all fitted with a much more sophisticated exhaust after-treatment system. This will also become a standard feature on NRMs with Euro VI engines.

There are currently no test emissions figures available for New Routemasters with the Euro VI engine, so no comparisons can be drawn between the NRM and the Euro VI hybrids listed at this time.

Bus Type

NO2 (g/km)

New Routemasters (Euro V)


Alexander Dennis E400H (Euro V)


Volvo B5H (Euro V)


Hybrid Bus Type

NO2 (g/km)

Alexander Dennis E400H (Euro VI)


Volvo B5H (Euro VI)


New Routemasters (Euro V1)


New Bus for London pollution

Question No: 2014/4205

Darren Johnson

How many of the 800 'New Routemasters' you have ordered will meet the Euro 6 air quality standard, and how many that fail to meet this standard will be allowed into the Ultra-Low Emission Zone?

Written response from the Mayor

I expect 494 of the 800 New Routemasters to be fitted with the latest Euro 6 engine and 306 with the Euro 5.

The Euro 5 buses are the cleanest diesel-electric hybrids of their generation in the fleet with nitrogen oxide (NOx) emissions close to the Euro 6 standard (a reduction of 80 per cent on a fleet average Euro 5 compared to 95 per cent for a Euro 6).

TfL will operate these buses in the ULEZ because of the marked air quality contribution they will make. No other types of diesel-electric Euro 5 hybrids buses come close to the New Routemaster for NOx and will not be allowed to operate in the ULEZ without modification.

TfL must spend its funds as cost efficiently as possible to raise air quality in London at the earliest time. Replacing higher emitting Euro III buses outside the ULEZ, for instance, would cut NOx from these vehicles by up to 95 per cent.

However, upgrading 306 New Routemasters from Euro V to the Euro VI standard would result in a vehicle NOx saving of 15 per cent. The cost would be £7 million to £15 million, depending on technical challenges faced, and would increase NOx savings for the ULEZ from only 51% to 52% in 2020 - a poor emission return by comparison. The latter strategy frees up resources to remove higher emission vehicles from London sooner and bring about more rapid change in air quality.

TfL is confident Euro VI engines delivers markedly better exhaust emissions after testing most types available on a standard London buses test cycle. This shows that in real-world conditions they deliver a step-change in performance.