Transportation engineers question the use of common practices and metrics

By Chris McCahill

This month, for at least the second time in a year, the Institute of Transportation Engineers has challenged its members to rethink common practices and metrics that are often thought of as objective and unbiased, but that convey values that aren’t necessarily in line with the greater public interest. In particular, these values emphasize the movement of vehicles above all other interests.

In an op-ed for this month’s ITE Journal, Jason DeGray, a licensed engineer and a member of the group’s advocacy committee writes that, if they view themselves only as tools for implementing public policy, its members may not be living up to its Canon of Ethics, which calls for advancing human welfare. “While engineers may not be experts in values,” he writes, “we can certainly educate the public discourse as to the results of ‘values’ based investment over time. We choose not to.”

DeGray argues that conventional approaches to engineering, developed over years of outward suburban growth, are particularly biased toward motorized road users—most noticeably in urban areas. He points to a recent incident in Springfield, MA, that left a 7-year-old dead and two others injured, and sparked a debate among ITE members over the ethical responsibility to provide a crosswalk in that location even if common practices and metrics might suggest otherwise.

A feature article in the ITE Journal’s August 2014 issue, titled “Decisions, Values, and Data: Understanding Bias in Transportation Performance Measures,” gives an example of one such metric—level of service—and explains precisely how it reflects values and biases inherent to transportation design. The authors summarize these values as follows:

  • Cars are more important than people;
  • We should provide much more road capacity than needed; and
  • New development should occur in suburban areas, rather than in existing urban areas.

Instead of relying on firmly held metrics that prioritize vehicle movement, the authors recommend that engineers and planners choose metrics that reflect the values that are most important to stakeholders. They argue that whenever engineers choose a specific performance measure, they are also calling attention to a particular issue (traffic delay, in the case of LOS) and thereby helping to direct public resources toward addressing that issue, often at the expense of other important issues.

The state of California and the city of Pasadena have both recognized this reality and are moving away from LOS in favor of measures that align better with public interests and desired outcomes. Engineers can also lead in these efforts, ensuring that their practices and metrics reflect interests like public health, equity, and sustainable economic development. In doing so, they play a key role in focusing attention, skills, and resources on issues that matter most to the communities they serve, and that engineers themselves believe are most important for advancing human welfare.

Chris McCahill is a Senior Associate at SSTI.