Plan.City London how-to series 10: PTAL Data Layer

In this episode, we'll explore one of the most informative planning focused data sets available inside the app, the PTAL data layer. PTAL stands for public transport accessibility levels, and it's a system used throughout London to evaluate how well connected different parts of the city are to public transport. This analysis takes several factors into account such as the walking distance to nearby transport stops, the frequency of the available services, and the availability of different transport modes. All of this combines into a rating that helps quantify how accessible public transport is from a given area. To begin, open the data layers panel and select the PTAL option. Once activated, you'll immediately see a color grid appear across the city. The colors represent different accessibility levels. Cooler blue tones indicate areas with poor transport accessibility, whereas warmer orange and red tones represent highly connected parts of the city. At a glance, this already gives us a very powerful overview of London's transport infrastructure. But the real strength of the PTAL data layer comes when we begin interacting with it. You can click on any cell in the grid and doing so reveals detailed information about that specific location both in the viewport and inside the PTAL panel itself. The panel now displays a list of the nearby stations and stops contributing to the PTAL score. Each entry contains several pieces of information. The transport mode such as the bus tube rail or other services like the Elizabeth line or DLR, the station or the stop name. The distance from the selected PTAL cell and the available routes serving that station. This allows us to understand exactly why a specific area received its rating. For example, we can compare highly connected urban centers with more isolated areas and immediately see the transport infrastructure differences between them. Another important feature of this system is that it works both offline and online. By default, Plan City includes offline PTAL information, meaning the data set remains fully functional even without internet access. However, if your organization has access to a TfL API key, you can enter it through the app info section of the settings panel. Doing so allows the app to retrieve more up-to-date transport information directly from Transport for London. This can be particularly useful for professional workflows where recent service updates matter. One thing worth mentioning is how useful this layer becomes when combined with other plan city systems. For instance, you can overlay the PTAL with the future skyline developments. And that allows us to understand how well connected future projects will be. We can also combine it with the tube lines to provide additional context regarding the underlying transport network or we can use the PAL data layer alongside imported developments to help evaluate the accessibility of new proposed schemes. As you can see, this is far more than just a color map. It's a planning and accessibility analysis tool directly integrated into the 3D city model. And that's how the PTAL data layer works. Thanks for watching and see you in the next video.