FOI request detail

Lambeth Bridge - modelled journey time effects of schemes not being advanced

Request ID: FOI-1256-1718
Date published: 19 September 2017

You asked

I refer to This document refers to two schemes (as identified by references i and ii in square brackets in the following text) which TfL decided not to propose for consultation. "We also considered a number of designs at Lambeth Bridge north including [i] a signalised junction and [ii] a ‘Dutch style’ roundabout with a physically separated cycle track around the edge of the roundabout." Would you please supply copies of the analyses of effects on modelled journey times of i and ii. (Ie please supply data for these schemes of the same nature as set out in the table at the end of the consultation documentation for the scheme TfL did ultimately decide to take forward.)

We answered

TfL Ref: 1256-1718

Thank you for your request received by Transport for London (TfL) on 24 August 2017 regarding the recent consultation for our proposals at Lambeth Bridge.

Your request has been considered in accordance with the requirements of the Environmental Information Regulations and our information access policy. I can confirm that we hold the information you require.

Option [i] a signalised junction (with cyclists segregated in both space and time from ‘general traffic’) is the preferred option that the consultation refers to, the details that are requested for this are available on the consultation webpage including the modelling table

Option [ii] a ‘Dutch style’ roundabout with a physically separated cycle track around the edge of the roundabout. This was tested in mid 2016, prior to the signalised junction. This design was rejected due to the predicted problems it would cause in managing the road network.

The modelling process is consistent across both design options. Base road network data was collected on street in 2015, whereas our proposals are predictions of the way we expect the road network to operate in 2018. This accounts for other schemes TfL have completed, or are committed to building by 2018, and any expected traffic growth on the network.

Our traffic modelling suggested that as a result of the ‘Dutch style’ roundabout proposals congestion and traffic queues would likely jeopardise the safe operation of strategic sections of the road network, such as Vauxhall Gyratory and Parliament Square, potentially further exacerbating network management problems in central London. Whereas the signalised junction option allowed us to ensure that these strategic points on the network could be better managed by using adjustable amounts of green traffic signal time.

The predicted impacts to all road users including pedestrians at Lambeth Bridge as a result of the ‘Dutch style’ roundabout proposals are attached.

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

Sara Thomas

FOI Case Management Team

General Counsel

Transport for London


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