# Using avoid options

Isoline calculations supports the same avoid options that normal route calculation used, but their effects are a bit different:

• An avoid option in route calculation would avoid using specific segments if possible, but still use them if required, issueing a critical notice.
• An avoid option in isoline calculation is excluding segments from the isoline, making sure the area only contains segments that would not result in critical notices during route calculation.

## Example: Avoiding controlled access highway

One can see the impact of the avoid options on the isoline by comparing requests with and without them.

curl -X GET \
'https://isoline.router.hereapi.com/v8/isolines?origin=51.487480%2C9.009091&range[type]=distance&range[values]=5000&transportMode=car'
curl -X GET \
'https://isoline.router.hereapi.com/v8/isolines?origin=51.487480%2C9.009091&range[type]=distance&range[values]=5000&transportMode=car&avoid[features]=controlledAccessHighway'


The resulting isolines are:

## Example: Empty isoline due to avoid options

If the isoline starts on segments that are avoided the resulting isoline will just contain the origin (as the user cannot calculate a route anywhere without getting a critical notice).

curl -X GET \
'https://isoline.router.hereapi.com/v8/isolines?&origin=51.490899%2C9.011935&range[type]=distance&range[values]=5000&transportMode=car&avoid[features]=controlledAccessHighway'