Recently, as part of a module final assessment for my MSc in Transportation Planning and Engineering, I was asked to respond to the question:
“Why does transportation planning remain critical in the 21st century?”
As someone who has spent the last four to five years, a formative period in my academic and professional career, focused intensely on — and unable to look away from — the countless injustices and failures that define many of our current local and global transportation networks, I found the question almost offensive. To ask whether transportation planning is still needed, I perceived, was almost to imply that some may think of the current mobility systems on which our societies rely as satisfactory.
(In 2006, for example, the UK’s road infrastructure was found to be reasonably-sufficient by an influential government transport study; if our road networks tend to be well-connected, why continue planning them?)
Of course, physical roadway connectivity is not the only measure of success by which our transportation networks should be judged, and neither is connectivity for only “traditional” road users, those driving motor vehicles. (I put “traditional” in quotes because there seems to be a collective amnesia regarding the fact that many of the world’s great cities were built in a time before automobiles, before people walking and biking were relegated to the sidewalks and derisively labeled “jaywalkers” for intruding on what was once their space in between them).
To respond to the question, I touched on several reasons why I thought transportation planning remained critical in the 21st century. To me, these include an increasingly-pressing awareness of the need for local and global climate-friendly mobility (while other sectors have seen significant improvements in emissions, transportation largely hasn’t budged and, in many countries, is the largest single source of carbon emissions) and continued technological innovation (by autonomous vehicle developers, for example, whose safety record is abysmal).
This idea of connectivity, though, stuck out to me. After all, most people, most of the time, don’t travel for the sake of traveling. They travel because transportation serves as a means to an end: one travels to access employment, shopping, support services, or connections to a community, for example. One travels to engage fully in their society. Clearly, physical connectivity is important because people have places to go.
Traveling, however, takes time. As a result, it’s not enough to simply say that two places are linked by transportation infrastructure. The time it takes to make the journey matters, too. Connectivity inherently has spatial and temporal elements; together, they can define the accessibility of a local network.
It’s important that every mobility network fulfills its critical role as a means to an end, allowing people to go about their daily lives safely and efficiently. I had a hunch that evaluating a transportation network through this lens — how well does it enable everyone to get where they’re trying to go? — would reveal inequalities. If this were to be the case, it would suggest that our current systems have shortcomings to be addressed through continued planning.
To examine this, I used Boston, Massachusetts, a city with which I am intimately familiar, as a case study. For each neighborhood in the city, I compiled data on race, unemployment, and travel time to work. Data are from the Boston Planning and Development Agency (neighborhood race distributions, 2017), the Boston Redevelopment Authority (unemployment, 2012, the most recent year from which I could find observations by neighborhood), and Go Boston 2030 (commute lengths).
The idea I hoped to examine was a simple one.
One would expect that commute time, as a proxy for local employment accessibility, and unemployment would be positively related. Neighborhoods with high average commute lengths could be assumed to have low employment accessibility, and therefore finding higher rates of unemployment in these areas would not be surprising. Furthermore, commute lengths aren’t randomly distributed throughout the city. Rather, neighborhoods closer to jobs centers, like Downtown Boston, would likely have shorter average commutes and lower rates of unemployment, while neighborhoods further from central job hubs would be those most likely to have higher average commutes and resulting higher rates of unemployment.
There’s nothing particularly nefarious about this: those who live closer to more jobs will have shorter commutes and less unemployment.
If, however, longer average commutes and higher unemployment rates were correlated also with race, that would suggest that the city’s current spatial layout, and (expected) variations in local employment accessibility, have the effect of segregating opportunity by race. The result would be tangible harm among neighborhoods of color, which would experience disproportionately-longer commutes and higher rates of unemployment than whiter neighborhoods. If this is the case, the current transportation network — which should provide equitable accessibility for all — would be insufficiently fulfilling this role, favoring some people over others. In response, transportation planning would be a critical tool to remedy the problem.
At the neighborhood level, I found essentially what I expected.
The six whitest Boston neighborhoods (the North End, Beacon Hill, the South Boston Waterfront, South Boston, Back Bay, and Charlestown) all have below-average unemployment and commute lengths. Meanwhile, of the six neighborhoods with above-average proportions of nonwhite residents, four (East Boston, Hyde Park, Dorchester, and Mattapan) have above-average unemployment and commute lengths.
It certainly seems to be the case that Boston’s current spatial arrangement tends to segregate employment accessibility and opportunity by race. I wanted to look more closely, though, so after the exam was submitted, I gathered data at the census district level for Suffolk County (from 2019). I replaced average commute length with a rate, the proportion of residents with commutes over 60 minutes. Either way, this term should reflect a neighborhood’s accessibility to employment opportunities.
Mapping the proportion of nonwhite residents, the unemployment rate, and the proportion of residents with a commute longer than 60 minutes, these appear to be generally-related neighborhood characteristics.
Consider Roxbury, Dorchester, and Mattapan, the wide swath of bright yellow running south from Boston’s geographic center in the map of nonwhite residents. These neighborhoods are not close to downtown, especially parts of south Dorchester and Mattapan, so it is not surprising that their commutes are longer, or that their unemployment rates tend to fall above average.
These maps tell me, though, that this positive relationship between distance from downtown Boston and commute time doesn’t apply equally to all census areas. For example, the neighborhoods of Jamaica Plain, Roslindale, and West Roxbury also extend south from Boston’s geographic center, running along its western border with Brookline. While the proportions of long commutes in these areas do increase with distance from downtown, they appear to do so much less severely. As a result, their unemployment rates appear to increase much less severely, too. It is no accident, I believe, these neighborhoods are more white than their counterparts to the east.
Simple scatterplots of these three factors illustrate the correlation a bit more clearly.
Unsurprisingly, a positive relationship can be seen between high rates of long commutes and unemployment. Critically, however, these scatterplots illustrate that the proportion of nonwhite residents in a census district is positively correlated with both long commutes and the unemployment rate.
To me, this simple analysis demonstrates that transportation network accessibility and employment rates are related. Further, it demonstrates that the neighborhoods that are less white are those which are left underserved by worse accessibility — and therefore worse access to employment opportunity — than nearby whiter neighborhoods.
There are a lot of lessons to be taken, I think, including:
1) Transport’s function as a “means to an end” is not working for everyone equally.
This analysis would suggest Boston’s transportation network is fundamentally flawed, inequitably fulfilling its role as a means to an end throughout the city. Varying levels of spatial and temporal connectivity, of accessibility, disproportionately result in people of color having longer commutes and lower levels of employment. To me, that says, very clearly, that our transportation network isn’t done, and, therefore, that transport planning must remain critically important in the meantime.
2) Asserting causation here is complex, but correlation is enough to identify the existence of a problem.
I believe it’s no accident Boston is distributed as it is. Urban renewal and road building efforts in the United States disproportionately targeted the displacement of poor people and people of color. Government policies, explicit and implicit, worked to segregate neighborhoods by race and class. (Richard Rothstein’s The Color of Law is an excellent account of all the myriad of factors that contributed). Regardless of the complex causes, a problem exists today for transportation planners to solve. That’s not to say understanding these causal influences is unimportant; rather, the work of identifying the mechanisms that have influenced the city’s modern spatial layout over the past few centuries should not stand in the way of proactively addressing today’s inequalities.
3) Government provision of infrastructure for improved accessibility is fraught with potential externalities.
How can government provide better transportation infrastructure and accessibility to employment without making an area more attractive, raising local rents, and displacing the very people improvement projects intended to help in the first place? The answer cannot be to leave “bad” neighborhoods alone so current residents aren’t displaced. Rather, the solutions that may preserve neighborhood affordability, such changes to land use, housing, or economic development policies, likely fall beyond the purview of transportation planners and engineers. These must come in parallel with improvements to transportation infrastructure for more holistic policymaking and planning.
4) Transportation planning and engineering, alone, are insufficient.
Transportation engineering — or worse, traffic engineering, a field with a historic reputation for single-minded attention paid to facilitating ever-increasing automobile flows — can’t alone get us very far. Transportation planning can get us further, but short-sighted and single-minded transportation policies have the potential to do more harm than good. What our cities need are leaders willing to provide holistic planning of transportation, land use, and economic issues together. If we are to achieve more just cities — if we are to achieve more equitably-connected transport networks — transport’s central, but not singular, role in complex urban environments as a means to an end reminds us that broad, people-centric, and multidisciplinary planning approaches are as relevant and important today as ever before.