Request ID: FOI-1859-2324 Date published: 25 September 2023
You asked
I have just received the email alerting me to the publication of the attached reports.
I wonder if you could help me please with the methodology and calculations of cycling volumes in the Monitoring Results document, please.
Also, on the bus journey times, does TfL have total times for the bus journeys the relevant stretches of road rather than the weighted averages please.
In addition, please can you provide INRIX data on average journey times for cars and cabs dating back to 2017 please.
We answered
Our ref: FOI-1859-2324/GH
Thank you for your request received by Transport for London (TfL) on 29 August 2023 asking for information about the Chiswick High Road consultation.
Your request has been considered under the requirements of the Environmental Information Regulations and our information access policy. I can confirm that we do hold the information you require.
I wonder if you could help me please with the methodology and calculations of cycling volumes in the Monitoring Results document, please.
Please see methodology in PDF.
Also, on the bus journey times, does TfL have total times for the bus journeys the relevant stretches of road rather than the weighted averages please.
The methodology used to calculate bus journey times does within the report not allow us to provide the underlying bus journey times mapped to the Chiswick sections.
Our calculations look at all buses calling at each bus stop to bus stop section ( a combination of different bus services for each). Bus journey time per km for each Chiswick bus corridor section is provided as a weighted average weekly bus journey time of all bus services for the period of investigation usually 12 hours (07:00 to 19:00) based on bus frequency (this means the corridor average is skewed towards the higher frequency routes), for each bus stop to bus stop pair within the Chiswick bus corridor section which is then summed,.
The route based journey times are found by summing the total weighted average journey time across all the bus stop to bus stop links along the bus corridor and dividing by the length of these bus stop to bus stop links to give the bus journey time per km figure, used in the report.
This enables direct comparison across different bus corridor sections.
As different combinations of bus services use each bus stop to bus stop pair on which the calculation is based, we would need to build a different report to provide the individual bus service journey time for each bus stop to bus stop pair.
In addition, please can you provide INRIX data on average journey times for cars and cabs dating back to 2017 please.
Inrix weekday average journey time data (07:00 to 19:00) for Chiswick High Road west section and Chiswick High Road west section is supplied in both directions, as spreadsheets in the attached zip file..
Below are the charts showing the location of both sections of Chiswick High Road plus charts of the data provided.
Note the Inrix data does not go back before 2019. TfL’s contract for this data only started in 2019.
Chiswick High Road west section
EASTBOUND
WESTBOUND
Chiswick High Road east section
EASTBOUND
WESTBOUND
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.
If you are not satisfied with this response please see the attached information sheet for details of your right to appeal.
Yours sincerely
Graham Hurt FOI Case Officer FOI Case Management Team General Counsel Transport for London
