Here we are again: talking about a connectivity metric that is given disproportionate power in planning decision-making.
Who is SAM?
The draft London Plan (DLP) [1] introduces SAM – the Sustainable Access Measure – and embeds it in the Optimisation Framework [2] and the basis for car-parking standards. A higher SAM score will support greater density, tightening the expectation that development should minimise parking and make efficient use of land. SAM also features in the tall building location criteria and aspects of industrial land policy.
SAM measures travel times to jobs, services and amenities by public transport and on foot. TfL developed it to “provide a granular, pan-London metric which reflects the ability of a typical Londoner living in a given location to meet their regular travel needs by sustainable, space-efficient modes alone.”
Interestingly, SAM is absent from the Green Belt policy PV7 – for which applicants are to assess connectivity on a case-by-case basis (we’ll write more on this next time).
SAM is not PTAL…
SAM appears to have been designed to complement rather than replace PTAL. PTAL measures the time taken to walk to and wait for public transport in order to ‘access’ the public transport network, whereas SAM reflects whole journey times to various destinations and includes journeys made entirely on foot. SAM is intended as a London-wide comparator, showing how well connected a housing site is – or how car-reliant a neighbourhood may be – relative to others across London. PTAL, by contrast, should be used to compare access to the public transport network within the local area. Although both measures use the same 100m x 100m grid, their scales are not directly comparable. Confused yet?
… nor the Connectivity Tool
TfL is clear that SAM should be used in London, and not the Department for Transport’s Connectivity Tool. This is because SAM is calibrated on London-specific data, unlike the Connectivity Tool which is based on national average travel patterns.
The Connectivity Tool indexes scores across England and Wales against the best-connected location – Aldgate in London – so everywhere else scores lower. TfL, acknowledging that London is a special case requiring different treatment, has therefore developed its own tool…
Maybe we should take out London from the Connectivity Tool?!
SAM doesn’t cycle
That’s right… In London, our special case, where cycling makes up the highest proportion of journeys by mode in England and Wales, and where cycle infrastructure is arguably the best in the country, cycling is not included in the connectivity metric.
Apparently, cycling is excluded because it would skew the results – you can get a long way across London in the modelled time cap, and it would gloss over gaps in infrastructure.
If cycling does not count in London, where does it!?
The murky world of connectivity metrics
We love the details, and as we dig into the purpose and development of SAM, it starts to feel like another tool to muddy the waters of clear decision making.
SAM provides a more meaningful way of assessing transport impacts as, put simply, it measures access to opportunities, not merely proximity to a stop or station. Yet there are familiar limitations – it doesn’t account for severance, gradients, interchange quality, crowding, personal safety, service reliability or the actual experience of a journey.
By linking that score to density and parking, the DLP raises the stakes. SAM may provide a clearer starting point, but consent may still turn on the grey areas: how the score is applied, how local conditions are evidenced, and whether the proposed density and parking approach forms part of a coherent strategy.
For applicants, this is likely to make consent harder where parking is important to the proposal.
The challenge is most acute for employment and industrial proposals, where servicing, shift patterns, accessibility needs or operational vehicles do not fit neatly within a car-light narrative. For these sites, the case will need to extend beyond the number of spaces. It will need to critically assess whether alternatives are genuinely available and demonstrate that car parking can be provided without compromising density, public realm or Healthy Streets outcomes. This is essential if London is to achieve the industrial growth it needs.
We are well versed in these challenges
We are not here to argue with SAM. We help our clients prepare robust accessibility and connectivity strategies by combining the tools with local evidence, pragmatism and professional judgement. Brought in early, that perspective can inform land appraisal, density, access, parking and servicing before key design decisions become fixed.
[1] The DLP consultation runs to 15 October 2026, and TfL has explicitly asked for feedback on SAM itself.
[2] DLP § 2.24 – The Optimisation Framework provides a recommended net residential density range (in habitable rooms per hectare) that is expected for different settings and SAM levels within London.
