What is Catchment Area Analysis? (+ Tools & Examples to Improve Your Analysis)

13/11/21
28/10/21
Blog post
Victoria Akinsowon

If you’re looking to better understand your customer or user base, catchment area analysis is a great way to identify who your customers are and where they come from. 

In this article, we’ll explain the benefits of catchment area analysis, the different ways in which you can create catchment areas and the top tools you'll need to run a catchment area analysis yourself. But first, let’s start with what a catchment area is.

Contents

    What is a catchment area?

    A catchment area (also known as a trade area) is the geographic area from which businesses, organisations and services can attract customers or users.

    Catchment areas can be represented visually on a map. They can also be defined by several different factors, including travel time, the population within the catchment or distance.

    Why is a catchment area analysis important?

    Catchment area analysis is the process of using location data and catchment areas to analyse where your customers or users are coming from. Through catchment area analysis, you can visualise your location data to help you:

    • Choose the most profitable location for your business

    • Identify where to launch new services, such as healthcare services

    • Understand which location your target audience can access the most easily

    3 ways to calculate catchment areas

    1. Use distance-based catchment areas

    Distance-based catchment areas are defined by the distance around a location. This simply involves drawing a distance radius around a site and is the most basic approach to catchment area analysis.

    Because distance-based catchment areas take an ‘as the crow flies’ approach, it's often not accurate enough for most catchment area analyses. It also doesn’t consider the reality of how we travel. For example, public transport is an important mode of transport, particularly in urban areas. However, distance-based catchment areas take only distance, not public transport times, into account.

    Let's take the image below, which shows a 20 km radius catchment area around a site. Although you may be within 20 km of the site, we still don’t know how easy it is to reach by public transport, or even other transport modes like driving or walking.

    distance catchment area
    Distance-based catchment areas are often not accurate enough for catchment area analysis

    2. Use travel time catchment areas

    Travel time catchment areas are based on the journey time to a site by a specific mode of transport.

    Travel time catchment areas are created using isochrones – these are shapes that show all reachable locations around a starting point within a given time limit and by a mode of transport. 

    Creating catchment areas by journey time and transport mode gives you a more accurate picture of how accessible a location is. This is a key factor to consider when choosing where to locate a new site or consolidate existing ones.

    The image below shows a 1-hour catchment area for driving, created  with the TravelTime API:

    drive time catchment area
    A 1-hour driving catchment area

    We can see that this isochrone is considerably different from the distance-based catchment area above. This is because this drive time catchment area shows all the locations that are reachable within 1 hour by driving. The isochrone reflects contextual factors like congestion, roundabouts and other features specific to road networks.

    Why use drive time catchment areas?

    Drive time catchment areas are incredibly useful for several use cases. For example, you can use them to identify the areas where your potential customers are located and target marketing campaigns in these areas. 

    3. Bonus: Public transport catchment areas

    How accessible a location is by public transport is another factor you may want to consider in your analysis.

    The image below, created with the TravelTime API, shows a 1-hour public transport catchment area:

    public transport catchment area
    1-hour public transport catchment area

    We can see a significant difference in shape and size between this catchment area and two previous examples. This is because public transport networks create catchment areas that are inherently irregular in shape and hard to model accurately using only distance calculations.

    Reachable islands surround train stations or bus stops. However, these islands are disconnected from the rest of the catchment area because trains and buses only stop at designated stops. Holes occur when an area isn’t accessible within the time limit, but the surrounding area is.

    With the TravelTime API, you can create catchment areas for public transport and all other transport modes – even walking.

    Why use public transport catchment areas?

    If access by public transport is an important factor in your analysis, you'll want to consider creating public transport catchment areas.

    For example, if you’re considering where to locate a new office, you’ll want to consider how easy a potential office location is to reach for employees commuting by public transport.

    Watch the video below to learn more about creating public transport catchment areas:

    Top examples of catchment area analysis using travel time

    Analysing accessibility to key services - Financial Times

    travel time catchment areas_covid vaccination sites

    The Financial Times (FT) used travel time catchment areas to analyse how accessible Covid vaccination sites are across England by travel time and using different modes of transport.

    John Burn-Murdoch, Senior Data-Visualisation Journalist at the FT, said: “Most analyses of geographical service coverage focus only on the distance from point A to point B, but in reality, travel time is a much better metric — especially in a country like the UK where public transport service varies greatly from place to place.”

    Identifying the best location for a new office - Knight Frank

    catchment area_office relocation

    As we've seen, travel time catchment areas are a great way to see how accessible a location is by a specific mode of transport. Real estate consultancy, Knight Frank, uses this to help its clients find the best office locations.

    Since many employees commute by public transport, the Knight Frank team uses TravelTime to calculate travel time catchment areas based on public transport times.

    For example, if a potential office location needs to fall within a 30-minute commute time for all employees, the Knight Frank team can create 30-minute catchment areas around each location, assess proximity to key points of interest and ultimately identify which office location is best suited to a client.

    Choosing where to locate healthcare services - NHS South, Central and West

    travel time catchment areas_healthcare access

    You can use travel time catchment areas to see how people access healthcare services and plan resources accordingly. This could mean deciding how many staff should be available in a certain area or selecting the best location to provide a new healthcare service.

    The GIS team at NHS South, Central and West, an NHS support and transformation service, uses travel time catchments to support its strategic-level healthcare planning and day-to-day operations. For example, these catchment areas can be used to analyse patients' travel times and transport access to GP surgeries.

    What's more, this data can be layered with population data to calculate the population within each catchment area and determine the best location to set up a new service.

    Urban planning - Hatch

    walking catchment areas

    Hatch, a global management consultancy, uses travel time catchment areas as part of its location analysis for urban planning - aimed at improving urban infrastructure and sustainability.

    For example, Hatch's Urban Solutions team used travel time catchment areas to analyse the impact of a proposed extension to a metro station. They did this by creating walking time catchment areas around each of the potential new station locations and layering this with other datasets.

    Targeting local marketing campaigns 

    You can use travel time catchment areas to identify local trade areas where potential customers are located.

    By filtering reachable locations with your chosen time limit, you can identify how and where to push local marketing efforts, as this marketing agency did.

    4 tools to create travel time catchment areas

    Now that we've seen the benefits of using travel time catchment areas, what's the best way to create them?

    The following tools allow you to create catchment areas by travel time and transport mode:

    • TravelTime API: The TravelTime API allows you to easily create travel time catchment areas for any mode of transport, including driving, public transport, walking and cycling. Get a free API key here.

    • TravelTime ArcGIS add-in: For ArcGIS users, the TravelTime API integrates with ArcGIS Pro, allowing you to easily create travel time catchment areas within ArcGIS. Sign up for a free trial here.
    catchment area_TravelTime ArcGIS add-in
    Areas reachable within 45 minutes by public transport from two different New York locations
    • TravelTime QGIS plugin: If you use QGIS, you can also use the TravelTime QGIS plugin to create travel time catchment areas. Sign up for a free trial here.
    public transport catchment area_TravelTime QGIS plugin
    Public transport catchment areas created with the TravelTime QGIS plugin
    • TravelTime Alteryx macros: Finally, Alteryx users can use the TravelTime macros within Alteryx to create travel time catchment areas. Sign up for a free trial here.
    population catchment area_TravelTime Alteryx macros
    An example population catchment area using TravelTime Alteryx macros

    Conclusion

    A catchment area analysis is a good way to understand where your potential users and customer come from.

    Travel time catchment areas can help take your analysis one step further by offering a more accurate way to map coverage and understand accessibility.

    There are several ways to add travel time to your catchment area analysis: through the TravelTime API or any of our integrations with ArcGIS, QGIS or Alteryx.

    Want to learn how you can use TravelTime for your project? Just contact us below.

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