New York Subways cost seven times the average elsewhere in the world because public officials have stood by as a small group of politically connected labor unions, construction companies and consulting firms have amassed large profits

See The Most Expensive Mile of Subway Track on Earth by Alex Tabarrok.

"Blogger Alon Levy first drew attention to the fact that building a subway costs far more in New York City than elsewhere in the United States or the world. In a superb investigation the NYTimes updates that finding and investigates why:

The estimated cost of the Long Island Rail Road project, known as “East Side Access,” has ballooned to $12 billion, or nearly $3.5 billion for each new mile of track — seven times the average elsewhere in the world. The recently completed Second Avenue subway on Manhattan’s Upper East Side and the 2015 extension of the No. 7 line to Hudson Yards also cost far above average, at $2.5 billion and $1.5 billion per mile, respectively.

So why are costs so high? The NYTimes concludes:

For years, The Times found, public officials have stood by as a small group of politically connected labor unions, construction companies and consulting firms have amassed large profits.

Trade unions, which have closely aligned themselves with Gov. Andrew M. Cuomo and other politicians, have secured deals requiring underground construction work to be staffed by as many as four times more laborers than elsewhere in the world, documents show.

Construction companies, which have given millions of dollars in campaign donations in recent years, have increased their projected costs by up to 50 percent when bidding for work from the M.T.A., contractors say.

Consulting firms, which have hired away scores of M.T.A. employees, have persuaded the authority to spend an unusual amount on design and management, statistics indicate.

Where the Times piece goes well beyond what has been discussed before is the detail by which it supports these conclusions and the careful comparison with similar but much cheaper projects elsewhere in the world such as Paris.

It will not escape notice that New York buys subway construction the way all of America buys health care."