Coverage planning usually require complex and expensive tools to predict wave propagation using terrain models.
However since many years, Roger Coudé has developped a planning software for amateur radio, implementing the Longley-Rice model and using public terrain height maps. This software can also be used to make prediction of broadcast coverage.
Example for FM broadcast coverage prediction:
Transmitter maker Nautel has on their website a coverage prediction tool that can be used after registration:
It appears to be based on the Radio Mobile website by Roger Coudé. The limitation is that the antenna directivity diagram cannot be included, but for omni-directional transmissions this is quite handy. And it allowes estimations at the actual band III frequencies, which the Radio Mobile website doesn't.
The directivity diagram can be included in the model available on the Canadian Communications Research Center's website:
This requires registration as well, and is not as detailed as the Nautel results, but very useful with directional transmissions.