As 2013 unfolded and the promise of a new mayor came into view, the Forum for Urban Design hosted a series of meetings on urban development. As part of the forum, a variety of planners and designers submitted ideas for the Next New York. I highlighted one of those ideas — Alex Garvin’s waterfront light rail — in a September post on light rail for Red Hook. It is, of course, an old idea that won’t fade away and could make sense as a speedier connection to the jobs, shops, restaurants and subways in Downtown Brooklyn if the costs are right.

Today, that idea — and the rest of Garvin’s impractical line all the way to Astoria — is back in the news as The New York Times has discovered it. It’s always dangerous when The Times latches onto an element of urban planning as they tend to push real estate interests over transit needs, and their coverage of this idea as a mixed-traffic streetcar connecting waterfront areas that don’t need to be connected to each other follows a similar pattern. This is a Big Idea for the sake of Big Ideas and not to solve a discrete problem.

The presentation comes to us in a Michael Kimmelman column. I’ll excerpt:

There’s a wonderful term for the dirt trails that people leave behind in parks: desire lines. Cities also have desire lines, marked by economic development and evolving patterns of travel. In New York, Manhattan was once the destination for nearly all such paths, expressed by subway tracks that linked Midtown with what Manhattanites liked to call the outer boroughs. But there is a new desire line, which avoids Manhattan altogether. It hugs the waterfronts of Brooklyn and Queens, stretching from Sunset Park past the piers of Red Hook, to the Brooklyn Navy Yard, through Greenpoint and across Newtown Creek, which separates the two boroughs, running all the way up to the Triborough Bridge in Astoria. The desire line is now poorly served by public transit, even as millennials are colonizing Astoria, working in Red Hook, then going out in Williamsburg and Bushwick — or working at the Navy Yard, visiting friends in Long Island City and sleeping in Bedford-Stuyvesant. They have helped drive housing developments approved or built along the Brooklyn waterfront, like the one by Two Trees at the former Domino Sugar Refinery. But this corridor isn’t only for millennials. It’s also home to thousands of less affluent New Yorkers struggling to get to jobs and join the work force. So here’s an idea: bring back the streetcar.

The idea of a “desire line” is a literary device; it doesn’t mirror reality. Furthermore, the rest of Kimmelman’s column is replete with contradictions about this streetcar’s plan. Kimmelman opts for streetcars over buses because of “romance,” but and while there’s something to be said about the psychological impact of a streetcar, we’re talking about a half a billion dollars and massive upfront infrastructure needs for a mixed-traffic line that won’t do what Kimmelman wants it to do.

Here’s the question that needs to be asked first: Will the “thousands of less affluent New Yorkers struggling to get to jobs and join the work force” benefit from this streetcar route? What problem is a line near the waterfront from Red Hook to Astoria trying to solve? One Twitter follower put together a Google Map of the proposed routing, and you’ll see that the best it does is provide direct access to the Navy Yard, a decent sized job center in Brooklyn. As passé as it may be, jobs are in Manhattan or generally along subway lines, and this route doesn’t help improve access to subway lines. (It’s also a mess operationally with tight turns along narrow streets that would limit rolling stock length. It also parallels some bus routes, raising even more questions of need and cost.)

While Cap’n Transit believes that any area that could support light rail would be prime for a subway, if costs are lower and ridership falls in between buses and a subway, light could work. As I mentioned, we can’t dismiss the psychological edge they hold over buses, and with the right routing — dedicated lanes that run, say, from Red Hook to the Navy Yards via subway stations in Downtown Brooklyn rather than via the waterfront — they could solve the gaps in transit deserts. But we shouldn’t, as Deputy Mayor Alicia Glen does, love this idea simply because it’s new, romantic or big. Will the ridership justify the costs? Will the service connect to job centers and destinations or provide a faster way to get to New York’s developed subway network? Can we identify a need and support that need based on a thorough study? “Desire” isn’t enough considering how much this will cost.