A Big Opportunity to Reform the Vicious Cycle of Highway Expansion

How USDOT instructs states and metro areas to measure congestion will have huge impacts on communities of all sizes. Why? Because there’s a direct connection between how we decide to measure congestion and the resulting strategies for addressing it. And we need a measure that rewards solutions like aggressively investing in additional travel options, eliminating trips, reducing trip length, creating more places to live close to jobs or more effectively managing travel demand.

One of the most commonly used methods for measuring congestion today (and how proposed transportation projects would improve it or make it worse) is incredibly narrow and generates major criticism: roadway delay.

Every year, the Texas Transportation Institute releases their annual Travel Time Index congestion report that generates tons of news coverage across the country. Our piece from last year explained the limitations of comparing average rush-hour speeds to empty roads in the middle of the night, as TTI uses those middle-of-the-night speeds as their baselines for comparison. And then as a direct result of how congestion gets measured, many agencies attempt, at enormous price tags, to build enough road capacity to keep traffic moving at free-flow speeds during rush hour, usually bringing limited benefits (a few seconds of savings per commuter) at enormous costs.

Roadway delay, typified by TTI, also rewards places with long average commutes that happen at a high rate of speed, dinging places where people spend less time commuting or commuting shorter distances -- just because they travel at slower speeds compared to that baseline of average travel speeds at the middle of the night.

Another major shortcoming is that roadway delay focuses only on drivers -- not commuters as a whole, ignoring the millions of people opting out of congestion entirely by using various other options like transit, walking or biking or skipping the trip by telecommuting. Under a roadway delay measure, if a city has made investments like these that allow a large share of its commuters to skip roadway congestion entirely, it can be rated the same as another city where the average delay on the roads is the same, even if 100 percent of that second city’s commuters are stuck in traffic.

Delay is also blind to how many people a corridor is actually moving -- it only looks at the number of vehicles. Should two similar corridors, where the first moves three times the amount of people as the second because of a carpool requirement or a lane dedicated to high-capacity transit, have the same scores for delay just because the travel speed is the same?