Leo Varadkar (Dublin West, Fine Gael) | Oireachtas source

One could impose a levy scheme on businesses and households along the way, but there would be big downsides to that also. It would have to be a very high levy to fund the project. Much as people in County Meath would like to have the rail line, I doubt that they would be willing to pay levies of that scale to build it.

In the case of PPPs, it must be the type of project that will produce not just an economic return in the general sense but also an actual cash return that can be used to pay back the banks, bondholders and pension funds on which we rely to finance PPPs. They expect to be paid back. They are not charities, as the Deputy is aware. It is very difficult with rail projects because they do not produce enough cash to pay back the investment. That is why they are usually funded by the Exchequer. It is particularly a problem in the case of tunnels. There have been PPPs around the world for rail tunnels, but they have gone spectacularly wrong. As the PPP companies have been left with huge bills as a result, PPPs for tunnels are just not happening anymore. It might be thinkable for a stand-alone project somewhere, but it would be a little tricky where it was connecting to an existing line.

See this speech in context