For ~30 Billion you could build a DC to NY line that runs through Baltimore and Philadelphia.
"The Big Dig was the most expensive highway project in the U.S.[2] Although the project was estimated in 1985 at $2.8 billion (in 1982 dollars, US$6.0 billion adjusted for inflation as of 2006[update]),[3] over $14.6 billion ($8.08 billion in 1982 dollars)[3] had been spent in federal and state tax dollars as of 2006[update].[4] A July 17, 2008 article in The Boston Globe stated, "In all, the project will cost an additional $7 billion in interest, bringing the total to a staggering $22 billion, according to a Globe review of hundreds of pages of state documents. It will not be paid off until 2038." http://en.wikipedia.org/wiki/Big_Dig
PS: It was probably not worth the cost: "The result was a 62% reduction in vehicle hours of travel on I-93, the airport tunnels, and the connection from Storrow Drive, from an average 38,200 hours per day before construction (1994–1995) to 14,800 hours per day in 2004–2005, after the project was largely complete.[28] The savings for travelers was estimated at $166 million annually in the same 2004–2005 time frame.[29] Travel times on the Central Artery northbound during the afternoon peak hour were reduced 85.6%.[30]"