Clarification regarding TfL digital camera data - countlines 22097 & 22082
Request ID: FOI-2968-2223 Date published: 02 March 2023
You asked
On 30th September 2021, a follow-up query to FOI-1192-2122 was made as follows:
“(2) There seem to be a number of discrepancies in the automated sensor data which might indicate that vehicles (in particular cycles) are being double-counted between different sensors / across different lanes.
(a) the data from “S62 cycle lane” and “S62 east” would seem to indicate that c.54% (average) of daily eastbound cyclists are still using the carriageway instead of Cycleway 9. For example on 30/3, “S62 east” shows 1,088 cyclists (60% of the daily total) using the carriageway vs only 735 eastbound cyclists on C9 (as per “S62 cycle lane”), which seems unlikely to be true.”
In response, David Wells (FOI Case Officer) wrote on 25/10/2021:
“The automated camera sensor on the carriageway (i.e. “S62 east”) is
not currently optimised for counting cyclists because it is prioritised to
other modes, and steps are being undertaken to improve the detection
algorithm. The automated sensor count data should be taken from “S62 cycle lane” (countline 22096) this captures the vast majority of cyclists on Chiswick High Street and count data from this location are used.”
A further query was made on 29/10/21 as follows:
“(1) You mention that the cycle counts from "S62 east" (22097) should be disregarded as the camera is not optimised for counting cyclists on the carriageway; does this also hold true for the cycle data in "S63 west" (22082) as well?”
In response, Mr Wells wrote on 10/11/2021:
“Answer: Yes. The data from “S63 West” (22082) should be disregarded (low absolute numbers were recorded in carriageway)…”
Subsequent to these queries, the cycle counts from countlines 22097 & 22082 were removed from the data files supplied by TfL in response to FOI-2004-2122.
In the data from 2022, the count of eastbound cycles from countline 22097 remains high as a proportion of all eastbound cycles at this location. Between January and September 2022, the data seems to indicate that an average of 33% of all eastbound cycles were counted on the carriageway rather than the segregated cycleway infrastructure.
Please could you specify whether any improvements to the detection algorithm for countlines 22097 and 22082 were made following the FOI responses on 25/10/2021 and 10/11/2021 - and if so, on what date were these changes implemented?
We answered
TfL Ref: 2968-2223
Thank you for your request received by Transport for London (TfL) on 10 February 2023 asking for information about automated vehicle sensor data, following previous requests about these carriageway digital camera sites.
Your request has been considered in accordance with the requirements of the Freedom of Information Act and our information access policy. I can confirm that we hold the information you require. You asked for:
Clarification regarding TfL digital camera data – count lines 22097 & 22082
On 30th September 2021, a follow-up query to FOI-1192-2122 was made as follows:
“(2) There seem to be a number of discrepancies in the automated sensor data which might indicate that vehicles (in particular cycles) are being double-counted between different sensors / across different lanes.
(a) the data from “S62 cycle lane” and “S62 east” would seem to indicate that c.54% (average) of daily eastbound cyclists are still using the carriageway instead of Cycleway 9. For example on 30/3, “S62 east” shows 1,088 cyclists (60% of the daily total) using the carriageway vs only 735 eastbound cyclists on C9 (as per “S62 cycle lane”), which seems unlikely to be true.”
In response, David Wells (FOI Case Officer) wrote on 25/10/2021:
“The automated camera sensor on the carriageway (i.e. “S62 east”) is not currently optimised for counting cyclists because it is prioritised to other modes, and steps are being undertaken to improve the detection algorithm. The automated sensor count data should be taken from “S62 cycle lane” (count line 22096) this captures the vast majority of cyclists on Chiswick High Street and count data from this location are used.”
A further query was made on 29/10/21 as follows:
“(1) You mention that the cycle counts from "S62 east" (22097) should be disregarded as the camera is not optimised for counting cyclists on the carriageway; does this also hold true for the cycle data in "S63 west" (22082) as well?”
In response, Mr Wells wrote on 10/11/2021:
“Answer: Yes. The data from “S63 West” (22082) should be disregarded (low absolute numbers were recorded in carriageway)…”
Subsequent to these queries, the cycle counts from count lines 22097 & 22082 were removed from the data files supplied by TfL in response to FOI-2004-2122.
In the data from 2022, the count of eastbound cycles from count line 22097 remains high as a proportion of all eastbound cycles at this location. Between January and September 2022, the data seems to indicate that an average of 33% of all eastbound cycles were counted on the carriageway rather than the segregated cycleway infrastructure.
Please could you specify whether any improvements to the detection algorithm for count lines 22097 and 22082 were made following the FOI responses on 25/10/2021 and 10/11/2021 - and if so, on what date were these changes implemented?
We can advise that there have been no improvement algorithms applied to count-lines 22097 or 22082 since 10 November 2021.
TfL has no current reason to apply specific algorithm improvements to these count-lines.
In the meantime, we will apply global improvement algorithms that will be applied to all cameras as and when they become available..
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
Jasmine Howard FOI Case Officer FOI Case Management Team General Counsel Transport for London
