# Working with Isochrones

## A guide to creating isochrones and exporting data from within them, using the TravelTime add-in for ArcGIS Pro

Isochrones show the area that is reachable from a starting point in a given amount of time, for a certain method of transport. These can replace distance radius areas to provide much more relevant catchment or trade areas.

Examples of using isochrones include:

• Calculating the number of customers within a 45 minute drive of different retail stores
• Assessing which office would mean the most employees having a 1 hour commute or less
• Determining the available workforce reachable from a number of potential real estate sites

In this tutorial, we will use the TravelTime add-in for ArcGIS Pro to calculate the isochrones around a number of retail stores, and compare the reachable population for a few different groups of stores.

If you haven't already installed the TravelTime add-in for Pro, you can get a free trial API key and download the extension here

#### Step 1

We have our store data in an Excel file, with lat-long coordinates for each store.

To add this data to the map, go to Map >> Add Data >> XY Point Data

Select the relevant file from the Browser, and make sure the longitude coordinate is in the X Field and the latitude coordinate is in the Y Field.

Run the tool.

#### Step 2

To calculate the reachable areas around each of the stores, use the Time Map Simple tool from the TravelTime toolbox.

If you are only interested in a few store locations, it may be even quicker to run the analysis by entering the individual addresses directly into the Quick Time Map tool – you can learn more about this tool here.

To access the Time Map Simple tool, open the Catalog Pane and navigate to TravelTime >> Simplified >> Time Map >> Time Map Simple

To calculate the area reachable by public transport, with a 30 minute journey time, to arrive at each store at midday, configure the tool like below:

Change the Result aggregation parameter to UNION to return one shape with all the isochrones combined. Change it to INTERSECTION to return only the area that is reachable from all the stores.

#### Step 3

Run the tool, and in a few seconds a new layer will be added to the map illustrating the areas reachable by 30 minutes public transport.

#### Step 4

Population data comes in various forms, depending on the country or region of interest. UK population data is available at a postcode level based on the 2011 census. To add this population data layer we once again use the Add Data tool and search for the relevant shapefile.

#### Step 5

Initially we want to focus just on the stores in London and the South East of England. To do this, use the Select tool and highlight just the isochrones related to these stores. Then right click on the isochrones layer, go to Selection, then Make Layer From Selected Features. Once again rename this layer to something more useful.

#### Step 6

To filter the population data into just the postcodes that fall within these isochrones, open the Data tab under Feature Layer, and select the Spatial Join tool. This is then configured as below:

#### Step 7

The result of running the Spatial Join tool is a new layer of just the postcodes that fall within the 30 minute public transport catchment areas of the London and South East stores.

As a next step you could run the Table to Excel tool (just search for this in the Geoprocessing pane) to export this population data into Excel for further analysis.