Overreaching unions. Layers of consultants. Squabbling jurisdictions. And as the article mentions, the fact that they build so infrequently that they essentially have to skill up from scratch every time and can never optimise or learn from previous mistakes.
There's a lot of information about this out there but that about covers it I think. Here's a nice quote from a nytimes article:
"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."
Paris is old, narrow, and managed to build a subway tunnel through/under the Catacombs for far less.
The major issue seems to be that construction unions do not negotiate with the public authorities paying for it, but the construction contractors, and the contractors are more than happy to just pass along the cost and pad their margins. https://www.nytimes.com/2017/12/28/nyregion/new-york-subway-...
It's not just that, it's an entire stack of unaccountable entrenched interests from top to bottom. Unions, contractors, MTA management, all the way up to the squabbling governor and mayor.
One of the most discussed is Madrid, but most every other city outside the U.S. has lower expenses, even those with comparable (or worse) labor and other costs. A simple Google search will provide plenty of articles and studies, such as http://lab.rpa.org/building-big-less/
Crossrail (the project which is to be branded "Elizabeth Line" although all the other "lines" are lines within some larger modal network, so arguably this branding makes no sense) was a huge project. From funding to today it's ten years and the basic idea (East-West tunnels through central London) is from the mid-20th century.
It's taken so long that projected peak system congestion _with_ the extra line is predicted to be worse than it was without the line when it was funded, even though its capacity is about 10 passengers per second through the core. The lines it's "relieving" are hopelessly over-capacity, so it will fill immediately when it opens AND it's expected to increase total usage because hey, there's this line from outside London right into the core, why not live there and commute...
But certainly it's a comparable problem, in the sense that e.g. Crossrail had to "thread the needle" fitting the new tunnels between existing escalators and the Northern Line underground rail tunnel that both remained in use during construction.
Very fast. And not just that. A big part of the cost and complexity of Crossrail isn't the tunnelling but rather the (re)builds of the stations, the remodelling and reconstruction of the above-ground street areas to increase capacity there too, and many other subtleties that people don't tend to think about.
It's the biggest civil engineering project in Europe, or so they say. And a big part of that is because you don't just massively increase transport capacity into the core of a major metro area. That would just overload all the other infrastructure.
> A big part of the cost and complexity of Crossrail isn't the tunnelling but rather the (re)builds of the stations, the remodelling and reconstruction of the above-ground street areas to increase capacity there too, and many other subtleties that people don't tend to think about.
The BBC's documentaries on the Crossrail are great at showing all of the complexity of building the thing and dealing with historic buildings, super-hard brickwork, archaeological discoveries, concert halls and more.
Crossrail is a well-done project. But just to be clear: there were fully 68 years of feasibility and planning studies prior to getting the funding for construction. Since then, it's been laudably smooth sailing -- but if one considers the pre-construction planning work, there's substantial room for improvement.