August 21, 2025 | New Open-Source-Tool PtAC

Public Transport Access Calculator (PtAC) enables simple assessment of the United Nations Sustainable Urban Development Goal 11.2.1

Exemplary results of PtAC calculations for the city of Manila
On the left, the spatial distribution of population points and the computed distances to the nearest public transport stop are shown in blue. Right: Cumulative population share by distance to public transport.
  • The Public Transport Access Calculator (PtAC) is an open source tool for assessing access to public transport.
  • It enables the assessment and monitoring of the United Nations Sustainable Urban Development Goal of 2015.
  • Publication of the corresponding scientific article "Introducing PtAC - an open source tool to assess SDG 11.2 using open data".

The United Nations adopted the 17 Sustainable Development Goals (SDGs) in 2015. These goals are to be implemented globally in order to promote sustainable peace, prosperity and protection of our planet by 2030. One of these goals is improved access to public transport, defined in section 11.2.1. The implementation of this goal in particular is often difficult due to a lack of standardised methods, technical expertise and data.

Automated calculation of urban transport connections

Researchers at the German Aerospace Centre (DLR) have developed the open source tool "Public Transport Access Calculator (PtAC)" as a solution. PtAC makes it easier for cities to track their progress towards achieving SDG 11.2.1. The open-source Python library combines remote sensing data from the World Settlement Footprint Population (to calculate population density in cities) with crowdsourced geodata from OpenStreetMap (to identify road networks and public transport). PtAC automates the calculation of SDG 11.2.1 and enables a globally applicable, transparent and reproducible approach to consistently monitor urban transport connectivity.

"PtAC is an important step towards a more sustainable future," emphasise the developers of PtAC Simon Nieland, Mirko Goletz, Daniel Krajzewicz and Daniela Palacios Lopez. "With PtAC, cities can more easily track their progress towards achieving SDG 11.2.1 and make data-driven decisions."

Effective with limited resources

The researchers tested PtAC in 33 cities worldwide and compared the results with reference values from UN-Habitat, the United Nations Human Settlements Programme. UN-Habitat collects data on global urban developments and parameters on an annual basis. PtAC has proven to be an effective tool for assessing SDG 11.2.1. The results show that there is a high correlation with the United Nations reference values. The study also shows that the method is particularly relevant for cities with limited resources.

With PtAC, local governments have a scalable tool for independent and constant progress analysis of their commitment to the UN Sustainable Development Goals without the need for specialised GIS skills. It provides a cost-effective way to support the prioritisation of infrastructure investments in areas of high need and potentially facilitate access to global funding linked to SDG performance.

PtAC is an open source tool and can be used by anyone free of charge.

Contact

Public relations team

Communication & Press
German Aerospace Center (DLR)
Institute of Transport Research
Institutional and Strategic Planning
Rudower Chaussee 7, 12489 Berlin

Team SKO

Strategy & Coordination
German Aerospace Center (DLR)
Institute of Transport Research
Institutional and Strategic Planning
Rudower Chaussee 7, 12489 Berlin

Ilka Dubernet

Acting Head of the Department
German Aerospace Center (DLR)
Institute of Transport Research
Transport Markets and Mobility Services
Rudower Chaussee 7, 12489 Berlin

Uwe Drewitz

Head of department
German Aerospace Center (DLR)
Institute of Transport Research
Space for Mobility and Transport
Rudower Chaussee 7, 12489 Berlin