Without Support from Federal and state governments, it would be difficult for railroads and transit agencies to fund the PTC deployment in such a large scale within next few years. Moreover there is no inter-operable system available in market which is acceptable by all the concerned parties.
First, railroads can afford to install PTC on their own, without public financial assistance. Remember, these are companies now investing about $10 billion annually in capital spending. Second, the inoperability problem will be resolved, and I expect reasonably promptly, now that the railroads are required to install PTC. Within days of the passage of the legislation, they agreed on interoperability standards. Much of the opposition to PTC was propaganda based, and you're not hearing the same opposition today from the carriers.