Possible my numbers are wrong, but based on the "1% of the project cost" appears this will cost 3.5 billion dollars in total; $305 billion total cost [1] * 1% of total = three billion fifty million for "dig once"

[1] "Congress passed the five-year, $305 billion “Fixing America’s Surface Transportation (FAST) Act” on Dec. 3, 2015, and President Obama signed the bill the next day."