Are there any US cities that are working on plans to use existing freight rail lines for commuter rail?

As an example, I noticed when I was in Tampa that their freight rail routes (mostly owned by CSX) could actually have decent coverage for commuter rail from the suburbs to downtown Tampa.

I also noticed that these freight rail lines seemed to very rarely have freight trains traveling on them.

Are there any US cities that are working on developing commuter rail lines that either share these freight rail lines, or would build their own lines right alongside them using existing right of way?