Request ID: FOI-3094-2324 Date published: 12 December 2023
You asked
Dear Transport for London,
It is an observed fact that the traffic signals on the B276 Marlpit Lane near the junction with the A237 Brighton Road in Coulsdon operate poorly.
At busy times, eg MF 0730-0900 and 1630-1800, the green time for Marlpit Lane is often as short as 20 seconds, followed by a long red of as long as 40 seconds while a small amount of traffic emerges from the Bypass, and then a few on foot cross the road.
This leads to very long queues on Marlpit Lane from Old Coulsdon, with delays frequently of several minutes, delaying thousands of drivers, and also the 60 and 404 buses.
Traffic also blocks back into the roundabout, obstructing movement south on the A237 past the station.
At quieter times, eg MF midday, the green for Marlpit Lane is as long as one minute or more, meaning long needless waits to exit the Bypass.
Why do the signals operate in this perverse manner?
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What communications has TFL received, eg from LB Croydon members or officers, or from the public, on this matter?
What has been the TFL reply?
How does TFL propose to rectify this issue?
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Please provide full details of the design timings at this location, including the phasing plans, explaining how the total cycle time, and the green time for each phase is set, and how this varies by time of day and day of the week, and notably by traffic demand.
What devices exist at this location to measure and act on traffic demand, and how do they work?
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How in general does TFL monitor traffic signals to ensure they operate as designed, and achieve the intended outcomes, and also avoid unintended negative results?
How has this applied at this location?
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It is an observed fact that most traffic off the Bypass turns left, and often no vehicles turn right during the green phase.
The pedestrian green man crossing phase could operate while traffic off the Bypass in the left lane has a green arrow filter, or after a short right turn green and with a longer left turn off the Bypass.
That means having separate signals for the left and right turns off the Bypass - easy enough to provide.
That would mean that when someone on foot pushes to cross and there is left-turning traffic, the two green phases could operate simultaneously, reducing wait times for all road users.
It would seem likely that this change would have a big Benefit-Cost ratio.
Will TFL actively investigate this option, with a view to early implementation?
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At the roundabout, entry from Marlpit Lane has two lanes.
Reading the Highway Code, it seems that traffic turning left to go south on the A237 past Coulsdon South station should always use the left lane.
Traffic going ahead into Cane Hill may use either left or right lane.
Traffic turning night onto the A237 to go north towards Coulsdon town centre should use the right lane.
The extremely small volume of traffic going up onto the Bypass should also use the right lane.
What data does TFL have on traffic volume and turn direction at this location?
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It is an observed fact that the main traffic movement from Marlpit Lane is north towards the town, with the second major movement turning left towards the station.
Some cars using exit three for the town enter the roundabout from the left lane.
This causes confusion and delays to left-turning and ahead-moving traffic.
What measures such as lane marking or lane-to-use signs would TFL use to help to ensure that traffic uses the correct lanes entering the roundabout from Marlpit Lane?
We answered
TfL Ref: FOI-3094-2324
Thank you for your request received by Transport for London (TfL) on 27th November 2023 – detailed below - asking for information about the traffic signals on Marlpit Lane, Coulsdon.
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. However, I am afraid it is not possible to source all of the information asked for within the costs limit for responding to requests, as set out under section 12 of the Freedom of Information Act. Under section 12, TfL is not required to provide information if it would cost more than £450 to determine if the requested information is held, and to then locate, retrieve or extract it from elsewhere. This is calculated at a rate of £25 per hour, equivalent to 18 hours work.
In this instance the exemption applies because the information has not been collated before and there is no quick, efficient or automated way of doing so. For example, you have asked “What communications has TFL received, eg from LB Croydon members or officers, or from the public, on this matter?” I have been in liaison with our Customer Services team to try and establish what communications may have been received from the public about these traffic signals. They have run an automated search of all correspondence received for November 2023 containing any of the phrases ‘B276’, ‘A237’, ‘Marlpit’, ‘Brighton road’, ‘Brighton rd’ and ‘Coulsdon’. This returned 160 cases for the month of November 2023 alone. TfL holds records of correspondence from the public going back seven years, and hence for that entire period the number of potential cases we may have received would very likely run to many thousands. These items of correspondence may or may not be about the traffic signals. In order to determine which are specifically about the traffic signals rather than other matters we would have to review them individually. Given the numbers involved this is not possible within the 18 hour costs limit. Answering your other requests for information would add to the costs burden further.
In order to bring your request within the costs limit you may wish to narrow its scope, focussing on the information that is of most importance to you. In doing so you may want to review the advice published by the Information Commissioner on how best to access information from public bodies, available on its website here:
Please note that should you choose to submit a refined request you should restrict it to requests for recorded information. Requests asking for explanation (i.e. most questions beginning “why” or “how”) do not fall under the provisions of the Freedom of Information Act, and should instead be directed to our Customer Services team here:
