Compass Informatics, has a long-standing relationship with the NTA and was tasked with applying the PTALs model to the greater Dublin area using the NTA’s local proprietary data.

Compass developed a solution with scalability in mind, i.e. allowing for future inclusion of additional variables/parameters in the PTALS index calculation.

About The NTA

The National Transport Authority or NTA is the transport authority for Greater Dublin and the public transport licensing agency for Ireland.

The NTA took over certain functions from the Department of Transport and the entire role of the Dublin Transportation Office.

The NTA operates under the consumer facing brand Transport for Ireland.

What are PTALs?

Public Transport Accessibility Levels (PTALs) is a methodology to accurately measure the accessibility of a point on a map with reference to the public transport network.

The method was developed in 1992 by the London Borough of Hammersmith and Fulham and was subsequently adopted by Transport for London (TfL) and applied to the Greater London Network.

The model reflects;

  • Walking time from the point-of interest to the public transport access points
  • The reliability of the service modes available
  • The number of services available within the catchment
  • The level of service at the public transport access points – i.e. average waiting time.

Project Requirement

The NTA’s planning and modeling teams needed to be able to assesses which parts of the network required investment and calculate the impact of making changes to services and infrastructure. 

Compiling data to model these types of changes is complex, requiring a deep understanding of NaPTAN, GTFS and geospatial data sets to provide accurate and defendable insights.

Compass’ Solution – PTALs

PTALs can be calculated with varying degrees of complexity so a phased approach was used so that new calculations were introduced iteratively.

Other models such as permeability and catchment analysis were also integrated to give better results.

The project included:

  • Development of a methodology for generating PTALS using local data.
  • The ability to use the following NTA datasets:
    1. Public Transport Stops
    2. Services and Frequency at Stops
    3. Walking Network
  • Functionality allowing the grid to be defined by the user to configure the PTALs calculator.
  • Deployment of tool to the NTA environment, specifically local desktops running ArcGIS.
  • The application uses a combination of Desktop GIS (ArcGIS Desktop) and SQL Server for data management and data processing.
  • An ESRI file GeoDatabase (fGDB) can be produced as an output, that includes the input datasets and the output PTALs grid.

A key requirement of the solution was  the ability to extend the parameters used in the calculation of PTALS.

Solution Snapshot

About TGI

Tracsis Geo Intelligence, a sister company of Compass Informatics, emerges with a sharpened focus on Earth Observation, Sustainability, and the UK Market.

Building upon the expertise and experience of Compass Informatics, Tracsis Geo Intelligence offers a comprehensive suite of geospatial solutions.

Compass Informatics is a leading provider of geospatial solutions, specialising in the application of GIS, IT, and mobile technologies across various sectors, including transportation, environment and natural resources.

Tracsis Geo Intelligence and Compass Informatics are both part of the Tracsis Group.

To learn more about this project, and how the solution provided may benefit your organisation, please contact our team at