## Use Bing Maps to calculate an isochrone to reach your customers

Isochrones are changing the way we estimate travel times. Imagine you are a store owner and would like to target customers that live within a 15-minute drive from your store with advertising for your weekly specials. Without Bing Maps, you could draw a circle on a map, guessing that radius represents about 15 minutes away, but it will not truly reflect the time it will take for customers to get to your store. For example, a customer living near a major transit route can live further away from the store than a customer living in a less well-served part of the city.

To meet this need we use an isochrone - a polygon (an area on a map) of expected travel time. It represents the locations that will take the specified time, or less, it will take to get to a specific point (your store, in this case). Estimating an isochrone correctly, including all the variables like traffic, road, and vehicle conditions, is very hard to do by yourself!  This is where Bing Maps Isochrone API comes in.

### Bing Maps Get Isochrones API

Using the Get Isochrones API from Bing Maps makes it very easy to calculate the isochrone. For our store example, we need to calculate a 15-minute isochrone for every store we have. We only need the coordinates (longitude and latitude) from our stores and the drivetime in seconds (15 x 60 = 900 sec).
`GET https://dev.virtualearth.net/REST/v1/Routes/Isochrones?waypoint=47.65431,-122.1291891&maxTime=900&key={BingMapsKey}`
To determine which customer is living inside the 15-minute drive isochrone, we first need the coordinates for every customer's address. Then, we simply loop through all our customers and use the Find a Location by Address API to get the coordinates.
`GET http://dev.virtualearth.net/REST/v1/Locations/US/WA/98052/Redmond/1%20Microsoft%20Way?key={BingMapsKey}`

### Point In Polygon

The last step is to check if a customer coordinate is inside one of our store isochrones. We use a Point In Polygon calculation (PiP) to determine if this is true. There are many libraries that can calculate a PiP, but there is also an easy API that can do this for you, the Bing Maps Point in Polygon Sample. Isochrones enable businesses to combine short travel times with targeted marketing. We now can target those customers close by a store with store-specific offers and promotions.