Request ID: FOI-1947-2324 Date published: 21 September 2023
You asked
I noted today a 10/11 year old diesel bus running in the London Borough of Sutton area, which would have taken the bus in and out of the ULEZ zone. In fact, I later saw an even older one. Out of interest, I put the registration number of the first bus I saw into the ULEZ checker and it came out compliant!
Please could you undertake FOI requests on the following:
The number of diesel buses currently still in use and what percent this is of the total number of buses in use.
The up to date emissions data for diesel buses. I would initially accept the 20 highest emissions and date these were last recorded, 10 lowest emissions and date these were last recorded, the median emissions figure and the emissions mode, with the bus age range and date the emissions data was last recorded
I would also like to understand the method used to ensure these old diesel buses became ULEZ compliant and the documented decision process as to why you could alter/amend your diesel bus emissions to become compliant but the general public could not.
We answered
Our Ref: FOI-1947-2324
Thank you for your request received on 5 September 2023 asking for information about diesel buses.
Your request has been considered in accordance with the requirements of the Environmental Information Regulations (EIR) and our information access policy. I can confirm that we hold some of the information you require.
There are approximately 3,700 diesel buses and 3,800 hybrid buses in the fleet – no matter the age of the bus, all diesel and hybrid buses meet the latest engine standard – Euro VI and are therefore all ULEZ compliant. Diesel and hybrid buses make up around 86% of the bus fleet.
TfL contracts buses to operate in the fleet for up to 14 years. Buses in the fleet that were not built as new Euro VI, have been retrofitted with cleaner Euro VI engines – to meet Euro VI emission standards. TfL undertook a retrofit programme between 2017 to 2020 to ensure all buses in the fleet met Euro VI/ULEZ standards. Since January 2021, the entire bus fleet has met Euro VI emission standards / ULEZ standards.
TfL monitors Air Quality in London, but does not monitor individual bus emissions as buses have been type approved by the Vehicle Certification Agency to the latest Euro standards and have On Board Diagnostics (OBD) for monitoring in service by the DVSA. In addition, TfL does not hold MOT emissions data.
Some commercial vehicles can be retrofitted to meet ULEZ emissions standards – details of which are on the TfL website:
