#grade-separation

Yonah Freemark, writing for Atlantic Cities, concludes that light rail systems have not been especially great for local transit or cities as a whole:

"In four of the five cities with new light rail lines, the share of regional workers choosing to ride transit to work declined, and the center city's share of the urbanized area population declined, too...while light rail may appear to make the public transportation system more appealing to the average rider, the construction of such a system will not automatically result in increased transit use."

There is one bright lining, however:

"There is one metric by which the metro areas with 1980s light rail investments 'thrived' more than others: core population....The median 1980s light rail metro saw its center city’s share of the urbanized area population decline by just 6 percent by 2012, compared to more than 10 percent for the 45 other regions with populations of more than 500,000 in 1980."

Freemark also points out that there hasn't been a new heavy rail (e.g., subway) system constructed in the country since 1993. This isn't to say that there haven't been new heavy rail lines: the DC Metro's Silver Line, New York's Second Avenue Subway,  However, I fear he also draws the wrong lessons:

"Does this mean we should cease investment in new light rail lines? Certainly not; in many cases, rail has provided the essential boost to reinvigorate communities, and in some cases it has also resulted in higher ridership than before: just look at Rosslyn-Ballston in the D.C. region or Kendall Square in the Boston region."

Of course, unmentioned there is that Kendall Square is served by the Red Line - a heavy rail line. The Rosslyn-Ballston corridor in Arlington, Virginia is served by the Orange (and soon, also Silver) Line - heavy rail. Not all rail is created equal, and while the benefits of "transit" writ large are readily apparent, so too is the fact that nothing has driven development, demand, and ridership like heavy rail.

This is a key question if North American cities are to consider modes like mixed-traffic streetcars as mobility solutions or as development tools. They might work better in the latter category, but they do nothing to solve mobility issues. Proper light rail, such as Freemark is writing about, is a better mobility solution but still only a halfway measure.

Maybe the better judge of success for a rail line, though, isn't even the dedicated right-of-way argument, but the grade separation. The three most-ridden light rail systems in the country all include significant portions of underground tunnels, as do four of the top six (and even the other two, the San Diego Trolley and Portland MAX, operate underground for stretches). The article Freemark links to about Rosslyn-Ballston and Arlington's renaissance reinforces this:

"Arlington planners and politicians were bold, optimistic and foresighted. They insisted that the [Metro line] run underground through Arlington, following Wilson Boulevard and Fairfax Drive, rather than running along the Interstate 66 right of way, which would have been the path of least resistance and at the lowest cost."

The Silver Line in Tysons Corner will help to distinguish between mere grade separation and underground vs. other modes as more beneficial than surface-running transportation. It probably should have been tunneled, but that moment is past. The key is to learn from light rail, elevated rail, and the undeniable and dramatic appeal of proper subways in forming future transit plans.