Request ID: FOI-1917-2122 Date published: 15 December 2021
You asked
I have been advised by tfl that I can make a FOI request for the traffic volumes and level of pollution pre and post ULez introduction and whether the ulez has made any reductions in pollution on this road ?--
Clarification received 25/11/2021: Pre ulez period could be for a 4 week period pre ulez and a similar period post ulez
We answered
TfL Ref: EIR-1917-2122
Thank you for your request of 23rd November 2021 asking for information about the ULEZ and the A406 Gunnersbury Avenue.
Specifically you asked:
“I have been advised by tfl that I can make a FOI request for the traffic volumes and level of pollution pre and post ULez introduction and whether the ulez has made any reductions in pollution on this road?”
On 25th November 2021 you clarified the request to state that the “pre” and “post” timeframes for the data should be four weeks. As explained in my subsequent acknowledgment email, given the timing of the request we have taken this to mean four weeks either side of the ULEZ expansion which came into place on 25th October 2021, rather than the inception of the original scheme.
Your request has been considered in accordance with the Environmental Information Regulations and our information access policy.
In answer to your first question - for traffic volume data on the A406 Gunnersbury Avenue - note that we do not have any permanent traffic counters and have not had any surveys completed during the stated time period on Gunnersbury Avenue. However we have an Automatic Traffic Counter (ATC) on Hanger Lane just beyond it’s intersection between The Mall, Gunnersbury Avenue and Uxbridge Road. The spreadsheet attached contains continuous hourly traffic flows from this ATC over the two periods requested. There is also a map showing the site location on the first sheet of the spreadsheet. The traffic flows come from our patched database which ingests the raw data at the most granular level and where required will populate any gaps within the data (due to telecoms issues or physical damage to a site) with a substitution value based on historic data. Substitution tables are created every month to keep them as up to date as possible, and therefore providing the ability to produce long term consistent trends for any given site within the network.
In answer to your second question - for the level of pollution on the A406 Gunnersbury Avenue - TfL does not hold this data. TfL does not routinely collect air quality data, but such information is published online by other organisations such as ‘Londonair’ - see here www.londonair.org.uk/LondonAir/Default.aspx - or ‘Air Quality England’ - see here www.airqualityengland.co.uk
Further to the above, please note much longer timescales are required to make any accurate assessment of the impact on air quality of the ULEZ expansion. For example, behaviour change among drivers has taken place over an extended period, including in the months prior to the expansion actually coming into effect as drivers readied themselves for the change. The recently published ULEZ “First Month Report”, which sets out the initial impacts of the expansion, addresses such points further. The report can be seen here:
If this is not the information you are looking for, or if you are unable to access it for any 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,
David Wells FOI Case Officer FOI Case Management Team General Counsel Transport for London
