I would like to formally lodge a Freedom of Information request, for: 1) the data supporting the view that the grid-lock on Church Road, Anerley Hill and Central Hill is caused by the collapsed building on Church Road 2) the data supporting the view that the grid-lock on the above roads has been created by Croydon Council’s closure of the Auckland Road and it’s “hill” roads 3) given the interlinked/contributory nature of the two factors, please provide the rationale for TFL taking the position that the problem will be completely resolved once the scaffolding supporting the collapsed building is removed. Please acknowledge receipt of this email and your expected timeframe for responding.

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TfL Ref 1259-2021

Thank you for your request received by Transport for London (TfL) on 4 October 2020 asking for information about traffic in Church Road, Anerley Hill and Central Hill, Se19.

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.  Our answers to your three points are below:

1. the data supporting the view that the grid-lock on Church Road, Anerley Hill and Central Hill is caused by the collapsed building on Church Road

The junction of Westow Road and Church Road has been modelled in LINSIG software to assess the impact of the temporary signals. LINSIG provides the length of queue on each arm in meters as well as Degree of Saturation. Degree of Saturation (DoS) is a percentage representing the amount of traffic demand through the network, compared to the amount that is physically able to move through the network with the available green time. Over 100% DoS results in the traffic waiting to not pass through on the green signal so the queue will continue to build.

It can be seen below that previously the junction at Church Road and Westow was already operating at maximum capacity with higher demand than the available capacity. The temporary signal has less capacity and hence queueing and DoS has dramatically increased.

           

AM	Degree of Saturation %
Approach	Before	Temps	Increase
Church Road Southbound	106%	164%	58%
Church Road Northbound	122%	162%	40%
Westow Road	19%

PM	Degree of Saturation %
Approach	Before	Temps	Increase
Church Road Southbound	123%	179%	56%
Church Road Northbound	105%	147%	42%
Westow Road	19%

AM	Mean Max Queue (m)
Approach	Before	Temps	Increase %
Church Road Southbound	59	220.0	273%
Church Road Northbound	143	275.0	92%
Westow Road	1

PM	Queue (m)
Approach	Before	Temps	Increase
Church Road Southbound	159	323	103%
Church Road Northbound	53	176	232%
Westow Road	1

1. the data supporting the view that the grid-lock on the above roads has been created by Croydon Council’s closure of the Auckland Road and it’s “hill” roads

Whilst the closure of Auckland Road has contributed to the congestion on Church Road it is not solely responsible. Currently it is not possible to separate data relating to the closure from the temporary signals. Engineers have attended on site to observe the traffic behaviour and reviewed the local road network to extrapolate where traffic is diverting from the Auckland Road closure.

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1. given the interlinked/contributory nature of the two factors, please provide the rationale for TFL taking the position that the problem will be completely resolved once the scaffolding supporting the collapsed building is removed.

We have not taken a position or stated the situation will be completely resolved.  We consider that until the collapsed building issue is resolved it is not possible to adequately assess the traffic impact of the LTN.  Removal of the temporary signals, not associated with the Auckland Road LTN, are a necessary precursor to a better understanding of the impacts of the LTN.

If you are considering submitting a further FOI request please think carefully about whether the request is essential at this current time, as answering FOI requests will require the use of limited resources and the attention of staff who could be supporting other essential activity. Where requests are made, please note that our response time may be impacted by the current situation.

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

Lee Hill

FOI Case Management Team

General Counsel

Transport for London

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