Applicants are strongly advised to seek clarification using the TfL pre-application advice service before starting to develop traffic and highway modelling so that a programme for review and audit can be agreed with the relevant parts of TfL. It should be noted that depending on the specifics of the proposal and modelling required this process can be lengthy - therefore engagement at the earliest opportunity is advised. TfL may also require the cost of model reviews to be covered, depending on the scale of the assessment.
The following areas should be discussed and agreed with TfL:
Following agreement of the model scope, the following steps should be undertaken:
Following sign off of the base models by TfL, the proposed models can then be produced:
Where mitigation is required to make acceptable development which would otherwise be unacceptable in planning terms, it is expected that this will be secured in full at no cost to TfL. There will normally be a requirement on a developer to enter into a Section 106 agreement, and where necessary a Section 278 agreement, to deliver highways improvements.
However it is acknowledged that in some circumstances, and in particular in areas where a large amount of growth is anticipated, it may not be realistic to expect a single development to deliver all the highways mitigation required. In these instances funding may be secured through limited pooling of contributions, Section 106 agreements or other mechanisms designed to secure money for transport infrastructure necessary to support development in the defined area. Importantly, it will be necessary to consider whether any restrictions on the occupation of developments prior to mitigation being delivered are necessary.
If a development is granted planning permission, any changes to the highway network for which TfL is responsible will require a scheme approval from TfL. This approval will consider the impacts of the proposals on all modes in line with TfL's network management duty. These webpages include guidance on the process for entering into a Section 278 agreement, but where alterations to traffic signals are proposed as part of Section 278 works, the scheme will need to be incorporated as part of TfL's existing work programme.
TfL will audit the design of new signals and any associated modelling, and produce a Traffic Signals Supplementary Report (TSSR), which will recommend whether or not a scheme should proceed. This process is covered in greater detail in both TfL's Traffic Modelling Guidelines and the Model Auditing Process Design Engineer Guide:
If the approach to modelling outlined above is adopted this will facilitate the TSSR process - it has the potential to save both time and money for the developer and for TfL. However, if the data used for the models at the time of TSSR submission is greater than 18 months old, TfL reserves the right to ask for data and assumptions to be checked or new surveys to be carried out as appropriate to ensure that any modelling reflects prevailing traffic conditions.
In some cases development proposals will be of a much larger scale or will form a significant part of an Opportunity Area (or Growth Area) as identified in the London Plan. In these cases the developer will be expected to undergo more extensive pre-application discussions with TfL and will require use of TfL's strategic highway and public transport models as set out in the Strategic Impact Assessment section. In such cases the impact on both public transport and highways will need to be assessed and balanced including the appropriate weight that should be given when using different models.