What would be the benefits of making public transportation free?

i need to know what are some of the benefits of making public transportation. i know that we would be paying in tax dollars.
More people would use it, which means that there would be less cars on the road. There would be less pollution and traffic because of fewer cars on the road.There would also be less accidents. I personally get to use the buses where I live for free because i am a college student. I even sold my car!
The ability to get a day