It'd be cheaper just to swim across

State spending millions every year pumping out [Boston’s] Big Dig tunnels | Boston Herald

"Big Dig engineers previously claimed that all leaks eventually would be sealed — one report predicted by September 2005. But now state officials admit the tunnels will always leak."

And maybe safer, too.

“…He said the amount of water seeping into the tunnels falls within federal safety guidelines."

Oh. Well then.