How many customers live within a 45-minute drive of this potential store location? If we relocate our office, what will that mean for our employees’ commute times? Which part of the city can I move to and still have a reasonable commute to work?

These are all questions that can be answered using isochrones: maps that show the areas you can reach within a travel time limit.

In this article, we’ll explain what isochrones are, the top use cases and how to get started creating your own isochrones.

## What are isochrone maps?

Isochrone maps, also known as travel time maps, are maps that show all reachable locations within a specified limit by a specified mode of transport. They are most used to depict travel times, such as drawing a 30-minute travel time perimeter around a start location. The isochrone below joins up all points within a 45-minute drive from the origin:

## Why use isochrone maps?

Isochrones offer a much better understanding of where’s reachable than an X-mile or kilometre radius circle. This is because isochrones take into account the reality of how people travel by different modes of transport.

The image below shows the difference between an isochrone and a radius map: you can see that many of the areas within a 20-mile radius are in fact not reachable within 45 minutes:

With the TravelTime API, you can create isochrones for any mode of transport.

Isochrones consider a wide range of real-life factors, including local geography, congestion and transport networks. This means that if you want to find out which locations are accessible, particularly for a given mode of transport, an isochrone will offer a better picture than an X-mile or X-kilometre radius.

## Calculate travel times to points that fall within an isochrone catchment area

Isochrones are a great way of visualising where's reachable within a travel time catchment area. But sometimes you don't need a visual, you simply need to identify which locations fall within a travel time catchment area, and which lie outside. This is often called finding a 'point in polygon'. Once you've found out whether the location falls within the area, the process of calculating the distance and time to each of these is called a distance matrix.

Try our free point in polygon tutorial

## 7 ways to use isochrone maps

### 1. Site selection

Isochrones can help you determine the best location for a new site, retail or office location. You can use isochrones to create catchment and trade areas to identify which locations are the most accessible. Layering this with additional datasets, such as population data, can provide even more insights. And with the TravelTime API and plugins, you can create isochrones for any mode of transport, including public transport.

For example, using TravelTime, real estate data analytics consultancy, Watson + Homes, can create travel time catchment areas to identify the best locations for clients to invest in real estate. The image below is of two isochrones that show all reachable locations within 15 and 30-minute drive times:

### 2. Public transport planning

Isochrones are a great tool for identifying locations that need additional transport infrastructure. Using TravelTime to create public transport isochrones can identify local transit blackspots or pinpoint areas in need of improved road networks.

For example, the image below shows that public transport connections between Brighton and Petworth could be improved as it's not possible to get there within 1 hour and 30 minutes.

### 3. Marketing

You can use isochrones to visualise retail catchment areas and determine where to place outdoor advertising or send in-app messaging as part of a proximity marketing strategy.

For example, a large supermarket may understand that most of their target audience is within a 15-minute drive of the shop location and create a drive time polygon and target customers in this area.

IKEA’s marketing team used TravelTime to create a drive time isochrone map to display all of the locations that are reachable within a 20-minute drive from one of their store locations in Ireland. The resulting map would help them determine which areas to target for localised marketing campaigns.

### 4. Sales territory planning

Allocating sales territories by journey time means that sales people can reach potential clients easily. It can also be a good tool for sourcing the nearest warehouse to supply a local area.

Thomas Sanderson, a manufacturer of bespoke window shutters and blinds, uses isochrones to create trade areas that identify the locations that need more attention from its travelling field staff. This helps increase the coverage of its sales force and provides a faster service to customers.

### 5. Property search

You can use isochrones on your property website to help users find a new home. Users can find the ideal home using their work location, maximum commute time and preferred transport mode.

The isochrone map below is an example from property website, Zoopla, which uses the TravelTime API to help users visualise all the properties within their preferred commute time:

### 6. Recruitment search

Recruiters can use isochrones to identify which locations they should focus on when looking to fill location-specific roles. For example, if a new call centre opens, employers will be able to see where to focus recruitment drive efforts.

### 7. Travel search

Travel websites can use isochrones to help users search for attractions, hotels or other points of interest based on their travel time and transport preferences.

## How to create isochrones

### For developers

TravelTime API

You can use the TravelTime API to add isochrone maps to your application. To get started, check out our documentation.

To learn more, our step-by-step tutorial shows you how to create an isochrone map for your application with the TravelTime API.

### For GIS & geospatial analysts

TravelTime API

You can use the TravelTime API to create isochrones as part of your location analysis. Check out our documentation to get started.

TravelTime plugins

If you don’t want to code or are already using GIS software, we have developed plugins for QGIS, ArcGIS and Alteryx that you can use to create isochrones for any transport mode. Learn more below:

## Using isochrones to see where’s reachable

Isochrone maps give us a better understanding of where’s reachable within a time limit.