How much of the $646.1 in Infrastructure was spent on the nec?
First of all,
this is a stupid argument to be having. The NEC is not the enemy of the LD network.
Let's not buy into the false premise that Amtrak is designed to be a profitable enterprise as it's currently structured, any more than a trucking company would be profitable if it were forced to pay for the construction and upkeep of interstate highways.
Duplicating the success of the NEC along similar corridors (like Brightline, California HSR and Texas HSR) is the best way of assuring there is a LD network that attracts more customers with more frequent service.
But anyway, a little accounting lesson: You have to break down infrastructure spending between routine maintenance (which is expensed immediately) and spending which is designed to last more than one financial period and is depreciated over time.
The $646.1 figure you're citing is capital spend, so it falls out of the operating category and is functionally irrelevant. The NEC is going to be more capital intensive because Amtrak owns most of that rail, where in the rest of the network it borrows rail and pays for access from other railroads. It's an apples and oranges comparison.
If we look at all operating infrastructure spend in FY19, Amtrak spent $83.6M total, on the core NEC services, with another $0.612M on ancillary Amtrak services against a total operating infrastructure spend of $352M.
So, for a service that accounts for $1.377 BILLION, or 41% of Amtrak's total operating revenue (including state service subsidies), you're talking about a 10% total operating infrastructure spend
where Amtrak owns its own rails.
If we're talking about capital expenditures, if we go back to the Level 1 accounts, you might be able to craft an argument that the NEC is not profitable without Federal grants. This is a bit misleading, since Amtrak runs the NEC like a true railroad that owns most of its own infrastructure and lends it out to other mostly commuter railroads. So, if you wanted to make the argument the NEC is not profitable, you could say that the entire operation (trains and rails) is operating at a $131M deficit net of Federal Grants.
However--even this is inaccurate. Amtrak's operating revenue (not including Federal Grants) minus operating expenses is still a positive $541M dollars.
In other words, at the operating level, for
every dollar of revenue on the NEC, taxpayers put in $0.37 and of that, ALL of it goes into capital (i.e. non-operating) uses.
Let's compare that to the National Network, where Amtrak mostly runs on leased rails.
Just looking at operating expenses,
for every dollar of revenue on the National Network (which includes State Support),
Federal taxpayers put in $1.07. For every federal dollar, only $0.72 goes into capital uses--the rest is covering operating expenses Amtrak cannot recover through ticket revenue.