Toll Roads

Hi,

I need to route between two destination with out toll roads. I use the option "disallows:toll road". The route response still returns few miles of toll road. 

The documentation mentions that disallows parameter guarantees that no toll road would be returned. But in our case few miles of toll road is returned.

Please see the url:http://open.mapquestapi.com/directions/v2/route?key=KEY&json={locations%3A%5B41.94881+-87.76283%2C+42.403942+-71.13997%5D%2Coptions%3A{disallows:toll%20road,shapeFormat:raw,prefers:highway}}

Can you please suggest what to use.

Thanks and Regards

Anjali