I gave my webinar talk about the Stockholm case and uploaded the video here. I don’t want to repeat either the case or my presentation thereof, but rather just point to one thing I said during the Q&A, about what counts as a megaproject. At the time I thought it was just an extemporaneous answer, but Sandy Johnston highlit it in his livetweeting, and I think it has some deeper meaning.

The issue at hand is that the definition of what a megaproject is is relative to local capabilities and practices. Building 5 km of subway tunnel is a megaproject if you’re an American city or a small European capital, but not if you’re a large European or Asian city. What I mean by this definition is that the usual properties of megaprojects are relative to local capabilities in the following ways:

• Megaprojects are hotly debated politically at the highest level – Crossrail and High Speed 2 were in the manifestos of both Labour and the Conservatives, and Grand Paris Express evolved with direct government involvement. In smaller cities, projects of similar levels of political importance are as one might expect smaller, like Citybanan (which is 6 km) and Nya Tunnelbanan (which is 19 km); in turn in Paris, extensions of the Métro totaling 19 km happen gradually without such political involvement.
• Megaprojects are institutionally new. Grand Paris Express not only was decided by the government, as an expansion of Métro service almost as long as the preexisting system, but also stretched project management capacity to the point of collapse, setting up the cost overrun; thus, the current project is being built using institutionally novel techniques including a single-purpose delivery vehicle with some design-build aspect.
• Megaprojects have a large, noticeable impact on the city or region if built; this can be an economic impact as with transport projects, but also a cultural impact, as with the Sydney Opera House, whose factor of 15 cost overrun is a case study in Bent Flyvbjerg’s oeuvre.

In a way, this means megaprojects are defined by cost. A 3 km expansion of the T-bana is not a megaproject, let alone a 3 km expansion of the Istanbul Metro, but a 3 km expansion of the New York City Subway is, because it’s a full order of magnitude costlier. A lower-cost city or country is one that builds more, simply because more projects are cost-effective, and thus it has more projects that are below the threshold of what counts as a megaproject and instead are routine extensions.

The Transit Costs Project hasn’t consciously made any comparison of megaprojects with technically similar non-megaproject transit expansion. The Istanbul case comes closest with its focus on Marmaray and smaller metro projects, but Istanbul Metro expansion writ large should be viewed as a megaproject (it’s certainly planned and politicized as such), and Marmaray is genuinely more technically difficult than just about any other urban rail project. A vulgar quantitative comparison across our database is probably infeasible – there are too few examples by definition, and, moreover, because megaprojects are in practice defined by cost, they’re likelier to be more expensive, even if their specific features do not raise costs.

That said, I do believe that megaprojects are likely to be costlier than equivalent non-megaproject extensions. Stockholm is not a good example for this because it isn’t doing incremental urban rail expansion, only megaprojects. But Paris is a good example, and the per-km cost rose dramatically in the wake of Grand Paris Express. In Barcelona, L9 is a very expensive megaproject; part of its mega- status comes from its worse-than-factor-of-3 cost overrun, but it’s also a large extension of the metro and its construction technique, a large-diameter tunnel boring machine, was new.

Berlin is more complex. We’ll need to wait to see which of the U-Bahn extensions under discussion are built, but those are liminally mega-, sharing some features of megaprojects (namely, political debate, consisting of modal warfare between U-Bahn and streetcar expansion) but not others (they’re not institutionally new and nobody claims they’re transformational for the city). That said, I tilt toward not viewing them as a megaproject, because the debate over them is more general modal warfare, in the same way I don’t think a project subject to debate over spending versus austerity or road versus public transport investment is a megaproject. The key political attribute is not that there’s any political debate, but rather that the political debate introduces politicization of technical decisions over alignment and construction methods; the modal warfare in urban Germany between streetcars and rapid transit is a proxy for much broader fight between consumption- and quality of life-oriented urbanism on the one hand (favoring streetcars and bike lanes) and production- and job access-oriented urbanism on the other (favoring rapid transit and also motorway construction).