Routing API v7 Developer's Guide
Avoiding Certain Road Types
To penalize the traversal of certain types of roads such as toll roads or motorways, you can specify a weighted routing feature within the specification of the routing mode.
For example, in the following code block:
motorway parameter specifies the routing feature and using
-2 for the weight determines how strictly route calculation should prioritize this routing feature.
If you specify
motorway:-2, the API excludes motorways from the route calculation if it is possible to find a route that avoids them. Otherwise, the route calculation includes motorways.