In regard to all TFL buses with diesel engines, whether or not they incorporate hybrid technology, please advise the following: 1. How many buses are fitted with fully automatic engine cutout technology to prevent emissions of exhaust fumes when the bus is stationary at traffic lights or bus stops? 2. What percentage is this of the total TFL diesel bus fleet? 3. How will this change with the expansion of the ULEZ emission Pollution control zone to it's maximum extent in a few years? 4. Does TFL have any plans to adapt hybrid buses to use an external electrical supply (pantograph electrical pickup) as used on trolleybuses, electrified thameslink rail service and Croydon tramlink service?

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TfL Ref: FOI-0353-1920

Thank you for your email received by Transport for London (TfL) on 2 May 2019.

Your request has been considered in accordance with the requirements of the Freedom of Information Act and our information access policy.  I can confirm we hold some of the information you require. You asked for:

1.    How many buses are fitted with fully automatic engine cutout technology to prevent emissions of exhaust fumes when the bus is stationary at traffic lights or bus stops?

We don’t hold details of vehicles fitted with stop-start technology. Not all manufacturers produce buses with the stop-start engine idling feature as others use battery state of charge as part of their strategy for keeping CO2 from the exhaust pipe to a minimum. The Alexander Dennis ADL 400Hs from Euro VI and all Volvo B5s do have stop-start, and most new types of single-deck buses.

You will be able to obtain some numbers of these vehicles as soon as the new fleet position, as of 31 March 2019, is added to our website.  We aim to publish this in late summer at https://tfl.gov.uk/corporate/publications-and-reports/bus-fleet-data-and-audits.

Making a much bigger difference to overall emissions is the upgrade of the bus fleet to the ultra-clean Euro VI engine emission standard. The new engine and its exhaust after treatment system reduces the most harmful pollutants to health – particular matter and oxides of nitrogen – by up to 80 and 95 per cent respectively. Around three-quarters of the fleet is now at this standard as a result of a rapid retrofit and replacement programme. The remainder will follow between now and 2020.

2.    What percentage is this of the total TFL diesel bus fleet?

Please see the above response.

3.    How will this change with the expansion of the ULEZ emission Pollution control zone to it's maximum extent in a few years?

Retrofitting mid-life buses and replacing vehicles closer to life expiry will make the biggest difference to reducing exhaust pollution from our contracted bus fleet. Around 2,900 buses entering the central Ultra-Low Emission Zone (ULEZ) already meet this standard, and we have 10 Low Emission Bus Zones outside the ULEZ which also have ultra clean buses exclusively using these corridors. As the entire bus fleet will be raised to the ultra-clean diesel standard by 2020, extension of the wider ULEZ area will not change our plans to assist London’s air quality. Specific plans for making the bus fleet cleaner were already in the Mayor’s Transport Strategy and reflected in the TfL Business Plan on the current timeframe.

4.    Does TFL have any plans to adapt hybrid buses to use an external electrical supply (pantograph electrical pickup) as used on trolleybuses, electrified thameslink rail service and Croydon tramlink service?

No, we do not have plans for high-powered plug-in or conductive/inductive charging in standard hybrids. Our strategy is to make the conventional bus fleet ultra clean as quickly as possible and then zero-tailpipe emission by 2037. As high infrastructure costs would be a significant barrier to the electrification of the network, we anticipate battery-powered vehicles developing longer ranges and being charged at depots, possible with some opportunity charging at safe intervening points, but not overhead power lines which would present significant safety and cost issues for London to overcome.

If this is not the information you are looking for, or if you are unable to access it for some reason, please do not hesitate to contact me.

Please see the attached information sheet for details of your right to appeal as well as information on copyright and what to do if you would like to re-use any of the information we have disclosed.

Yours sincerely

Eva Hextall

FOI Case Officer  

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