There’s a long-running dispute in the transit and planning world about the relationship of commuter rail to land use. Does commuter rail to suburban and exurban areas damage the environment by enabling sprawl, or help preserve it by taking long car trips off the road?
It can be hard to tease out correlation from causation in these circumstances. Over the last several decades, commuter rail systems in the nation’s major metropolitan areas have spread ever-deeper into the suburbs and exurbs, propelled by powerful suburban politicians who crave the glory of being seen as “relieving congestion” (one thing that almost anyone can agree American-style commuter rail can’t do). But does commuter rail being built to a sprawly area (like, say, Elburn, IL) make that area’s growth possible, or would the growth occur anyhow, with the potential rail riders simply driving to work?
Commuter rail has, for better or for worse, been an increasingly popular mode over the last several decades, so figuring out which way the dependency goes has been hard; there are plenty of areas that are sprawly without the benefit of commuter rail, but few that have actually lost service since the modern era of commuter rail (defined roughly as the takeover of bankrupt private services by government corporations in the ’70s and ’80s) began. Identifying such an area would allow us to determine whether the loss of service arrested growth, forcing it into a more compact area, or whether growth continued unabated, with commuters switching to cars.
There is one rather infamous example of such a loss of service–SEPTA’s former diesel operations. When SEPTA took over responsibility for the Philadelphia-area regional rail system (first through subsidies paid to the operating freight railroads, then directly) it inherited not only the core electrified services of the former Pennsylvania and Reading networks but several diesel-operated semi-intercity services, extending to Newark, NJ, Bethlehem and Allentown, and Pottsville/Reading. The two all-Pennsylvania branches, in particular, essentially served as extended commuter services for riders to downtown Philadelphia. By 1981, amidst a funding crisis and apparent apathy from SEPTA, service had ended on all three extended routes (diesel service remained for two more years on the shorter Newtown-Fox Chase branch).
And while (among other things) the end of diesel service caused SEPTA Regional Rail ridership to crater (it had been around 118,000 in 1975 and fell to around 85,000 in the mid-’80s after the opening of the Center City Commuter Connection), it also gives us an opportunity to examine suburban growth in the sudden absence of commuter rail. In the interests of seeing what happened, I examined population growth data from each of the towns along the Bethlehem/Allentown line and graphed them against growth trends in Montgomery and Bucks Counties and the Philadelphia MSA as a whole. I included data from towns along the line in those two counties, but not from Centre Valley or Hellertown, the two Lehigh County towns on the line aside from Bethlehem and Allentown, on the logic that those towns were much more tied to the economies of the Lehigh Valley than that of Philadelphia. Town- and county- level population data is from Wikipedia (because why dig into census sheets when someone else already did it?); MSA data from here. You can access the full sheet here: (Allentown Branch), but this is what’s important:
If the elimination of SEPTA’s diesel service had impacted suburban growth along the line, we would expect growth in those towns to fall during the ’80s. Instead, the towns as a total grew by 14%–11% more than the Philadelphia MSA as a whole, and 5% more than their containing counties. Growth fell a little below regional trends in the ’90s, but almost indistinguishably. Over the 60 years I examined, growth in the station towns either matched regional trends or was actually slower. It’s hard to argue from this data that there’s any correlation between the presence/absence of commuter rail service in a particular town and its growth.
There is both good and bad news for transit advocates in this (admittedly unsurprising) conclusion. On the one hand, that suburban sprawl can continue without transit means that advocates and agencies should feel free to resist the loud calls for expensive (in terms of both capital and operations) outward extensions from exurban politicians and commuters. On the other, growth will probably continue regardless of transit, so why not try to get people out of their cars? I haven’t seen extensive data from SEPTA’s Regional Rail operations in the wake of the diesel service eliminations, but the overall fall in ridership suggests that commuters from the areas that lost service chose not to drive to closer-in termini, but to drive all the way to Center City.
Should we build commuter rail to sprawl? On the whole, I think there are (as always) much higher priorities for transportation funding (and government funds in general). Commuter rail as currently conceived in the US is really expensive to operate, and sending it out to the far reaches of a metropolitan area is essentially a favor to exurban commuters and a subsidy for bad regional planning. But if the funds are available (and can’t be spent on anything better) and if suburban towns are willing to shape their land-use decisions (at least in the immediate station area) around transit, I suppose some service is better than none. Either way, if the Allentown Branch case is even remotely representative, it’s pretty clear that while commuter rail might be a subsidy for sprawlers, it isn’t actually a cause of new sprawl.