Realism on vehicle miles traveled
Seattle will reportedly go another year without specific targets for reduced driving per capita. The State, on the other hand, set targets in 2008 for vehicle miles traveled (VMT) per capita that seem aggressive at first glance, or like wishful thinking — 18% less by 2020, 30% less by 2035, and 50% less by 2050. Rather than wishful or aggressive, it’s more accurate to call them “aspirational” numbers that the State might support with additional legislation and spending choices over four decades.
But are the numbers realistic, and what do they mean?
Forty years out, it’s hard to predict the public’s reaction to anything. It seems likely that oil will be scarcer and more expensive in the mid-term, and this will cause reduced gasoline usage per capita by 2020, but by how much, and of that, how much will be reduced miles vs. improved fuel efficiency? And at what point will other types of fuel become popular? Will the new fuels usher in another era of cheap driving, and if so when? Transit will obviously play a big role in urban areas, and could in rural areas if driving gets too expensive and local leaders think long-term. Choosing to live near work and/or simply taking fewer trips are obvious ways most individuals can deal with high costs. If driving grows anyway, for example if oil stays affordable, growth will be somewhat limited since there will likely (and thankfully) be limits on how much we can or should expand our road system.
Even with improved transit, generations of improved proximity via infill and mixed-use, and more telecommuting, we don’t seem likely to reach the State’s goals without added impetus from extremely expensive oil and a lack of oil alternatives. In other words, a lot of ”stick” even if unintentional. The biggest reason is lack of density. For example, in the wildest dreams of those of us who love infill, the highest predictions suggest that even Seattle itself might reach about half the density of inner London, which suggests we won’t get anywhere near the walking or transit usage London’s density helps engender. And that’s Seattle, not our suburbs or rural areas.
Let’s assume for a second that the State’s numbers are the future. If so, perhaps surprisingly, the likely net effect would be fairly minor reductions in total VMT over the years. Based upon my shaky calculations, an 18% reduction from 2008-2020 coupled with 16% population growth (my wild guess, in line with 13% growth 2000-2009) would mean about 5% less driving overall. A 30% per capita reduction coupled with 40% population growth by 2035 would be a VMT reduction of just 2%. Only the more aspirational 2050 figure with the 50% per capita drop suggests a serious 20% reduction in VMT, assuming 60% population growth.
It’s interesting to look at some of the discussions about 520 and 99 in this light. Some people have suggested that peak oil will cause a sharp, massive drop in driving, and therefore there’s no need for either roadway. In other words, maybe we can tear them both down without replacement. This argument is used by some surface 99 supporters, and was part of a recent trial balloon about 520 by Knute Berger on Crosscut. For those of you who are hyperventilating, keep in mind that both are State highways, and both projects are controlled by electeds who largely consider replacement mandatory.
But consider: To believe the total VMT will fall substantially means believing that either the per capita drop will be far more dramatic than the State’s aspirational goals, or that population growth will be much slower, or both. It seems likely that these beliefs are way off, based on the very minor drop in driving during the recent high oil prices and near-depression, based on our region’s continued population growth in every year for generations except one during the Boeing bust, with no sign of stopping, and based on most projections for peak oil being one of managable decline followed by the rise of alternate fuels.
Yes, we should focus heavily on giving people alternatives to driving. In fact, it’s mission-critical for the region if you believe oil prices will rise, because transit uses less energy per rider in general, and walking and biking use none, and the regions that prosper will be ones that use energy efficiently. Personally, as a car-less enviro, I’d love to see a lot less driving, and support road diets on surface streets because they make the streets safer and friendlier. But as we look at transporation options, let’s be realistic!
