Bakerloo line extension – summary of business case and planning scenario work
3 January 2014 (updated 4 February 2014)
Background
The Mayor’s Transport Strategy includes a proposal to consider the feasibility of a southern extension of the Bakerloo line from Elephant & Castle. This could serve to improve transport connectivity and journey times in south-east London, and provide relief to congested national rail paths into central London.
Initial feasibility work has been completed looking at alignment options, engineering constraints, the scheme’s business case and the potential impact on development and regeneration along the length of the route. The preferred solution consists of a new tunnelled section between Elephant & Castle and Lewisham, and utilisation of existing national rail lines south of Lewisham to connect with Beckenham Junction and Hayes. Two alignment options exist for the tunnelled section through LB Southwark; the first option is via Old Kent Road, and the second option is via Camberwell and Peckham Rye. This can be seen in the figure below.
Elephant & Castle N Alignment Option 1
Old Kent Road
New Cross Gate
Camberwell
Peckham Rye Lewisham
Alignment Option 2 Ladywell
Catford Bridge
Lower Sydenham `
New Beckenham
Beckenham Junction
Clock House Bromley
Elmers End
Eden Park
West Wickham Hayes
Croydon
Figure 1- Bakerloo line alignment options
Under the preferred option national rail services would no longer operate on the Hayes line. The freed up train paths would be allocated to other national rail services in south-east London.
The capital cost of the scheme is estimated at between £2.2 – 2.6 billion (outturn prices including optimism bias, assuming construction starts in 2020). There is no funding in TfL’s Business Plan to pay for the scheme and given the current financial climate and other funding commitments this is unlikely to change in the short- to medium-term.
Outline business case appraisal
An initial business case appraisal of the scheme was completed in 2010, and this found that the benefit cost ratio (BCR) for alignment option 1 (via Old Kent Road) was 1.9:1. This business case appraisal was updated in September 2013 to take into account updated Railplan outputs based in turn on an updated LTS demand matrix for the year 2031. Note that the LTS matrix does not take into account the 2011 census or the resulting employment and population forecasts.
The Railplan modelling assumes the Bakerloo line upgrade is complete, giving a peak frequency of 27 trains per hour operated with new rolling stock. More services, up towards around 33 to 36 tph could operate if so required and be specified as part of the line upgrade. The service frequencies modelled for the extension were as follows:
Figure 2 – Assumed frequencies along line in AM peak, 2031
The benefits of the options have been calculated in accordance with TfL’s Business Case Demand Manual and include the following:
• Journey time savings
• Ambience benefits
• Highway benefits
Wider economic benefits have not been captured at this stage; however these could potentially be derived from the LTS outputs going forward. This would enable a better representation of the benefits and strengthen the case for the scheme future.
The capital costs of the scheme are derived from the technical feasibility study completed in 2007, updated to reflect more accurate estimates developed for the Northern line extension project. Similarly the operating costs are based on previous LU estimates but updated to reflect current estimates for the Northern line extension project.
The headline results of the updated business case appraisal, taking into account the benefits and costs outlined above, can be summarised as follows: All £ millions Build + renewal Operating Revenue Net Financial Benefits Ratio Option 1 £2,174 £729 £322 £2,582 £8,472 3.3: 1 Option 2 £2,597 £816 £320 £3,094 £8,184 2.6: 1
Table 1 – Summary of benefits and costs
The case for the routes down to Hayes/Beckenham Junction has increased significantly so that it is now well over the TfL pass mark of 1.5:1. This case will also be strengthened further once wider economic benefits are included in the assessment.
Option 1(via Old Kent Road) remains the stronger in terms of BCR due to the higher journey time benefits (with shorter journey times to central London) and the lower costs (with shorter tunnelling route). They do both, however, present a very strong case.
Planning scenarios
Work has also been completed into potential planning scenarios with the Bakerloo line extension in place, in order to better understand both the impact of the scheme on development and regeneration.
Three different scenarios were examined across the length of the route, split into three different land-use categories. The scenarios can be summarised as follows:
• Base scenario (without Bakerloo line) – this scenario covers the scales and type of development currently planned by boroughs
• High growth scenario (without Bakerloo line) – takes an optimistic view on a number of factors and opportunities that are likely to have a bearing on growth, including macro economic context, more flexibility in planning rules in town centres and high market demand
• Aspirational growth scenario (with Bakerloo line) – takes into account the impact of the Bakerloo line extension in unlocking development potential due to improved accessibility and connectivity. A higher percentage uplift has been applied along the length of the proposed route.
The table below shows the indicative development scenarios for each land-use category: Southwark Lewisham Bromley Total Residential Units Base 45,564 33,121 13,138 91,822 High Growth 51,506 37,303 38,422 127,232 Aspirational 54,516 38,568 38,549 131,633 Retail (sqm) Base 144,251 114,673 207,041 465,964 High Growth 178,480 126,386 228,750 533,617 Aspirational 183,500 129,117 229,439 542,056 Office (sqm) Base 743,621 177,163 147,738 1,068,522 High Growth 844,096 177,593 346,609 1,368,298 Aspirational 852,973 179,121 347,217 1,379,310
Table 2 – Development scenarios by borough
These scenarios do not take into account latest proposals on development opportunities as identified within the proposed Further Alterations to the London Plan, which could potentially alter assumptions on capacities at certain town centre locations. Further work is required to understand the scope and extent of potential third-party contributions (for example through CIL) towards the Bakerloo line extension from these scenarios.
Next steps
It is planned that an update on this work will be provided to the Mayor within the next 2-3 months. Possible next steps for taking forward the scheme and building on the feasibility work completed hitherto are currently being scoped.