Last month, the Washington Post’s Dr. Gridlock column profiled DC’s various new transportation investments might change transportation in the District. However, Dr. Gridlock used some odd phrasing to frame the city’s varied goals:

“In the Sustainable D.C. plan we released earlier this year,” the mayor said at the crosswalk event, “we set an aggressive-but-realistic goal of increasing the use of public transit, biking and walking to comprise 75 percent of all commuter trips in the District in the next 20 years.”

In other words, Gray told me afterward, the future of city travel is about sharing routes safely. Look for more bus routes, streetcars, bike lanes and devices such as the pedestrian signal, which can make walking safer and more popular without infringing on people’s ability to drive autos.

But for any city, getting three of four commuter trips done without cars is a major shift in people’s behavior. Why set the target so high?

“We’re looking at adding 250,000 people over 20 years,” Gray said. “If everyone drives, that’s unsustainable.”

Is the Sustainable DC goal really setting the bar ‘so high?’

First things first, the Mayor is absolutely right: adding 250,000 new residents would not be sustainable if everyone drove. The good news, however, is that adding that many new people to the city is entirely complimentary to increasing the use of non-auto transport modes. There is no ‘if,’ those 250,000 new residents will not all drive.

What about that goal of 75% of trips by non-auto modes (with 25% of trips by bike or on foot)? First, let’s consider where we are today. On Page 80 of the full plan document:

The data is commute mode share from the 2010 Census for DC. That is, residents of DC who work (and therefore commute to work). The usual limitations apply; this data is for commute trips only, it only counts the primary mode for the commute (if I walk to a bikeshare staiton, bike to a Metro station, then ride a train, and walk to work – you wouldn’t know it from these stats), and it only applies to DC residents, not to all commuters into DC.

Looking at that 2010 data, the goal is a strong one, but hardly unreachable. Contrary to Dr. Gridlock’s focus on commuters from outside the city, basing the data on DC residents shows how close to the goal we already are. If you look at the 75% goal through the lens of the region (where 15.4% commute via transit), it indeed looks like a high bar. From the view of the city, however, the non-auto share keeps growing.

Not only are non-auto modes growing in their share of the commute, but the city is growing in population. Given DC’s fixed boundaries (no annexation of our neighboring states here), any growth in population, by definition, means an increase in DC’s population density. This growth is complimentary to the goals of increasing use of non-auto modes. Infill development, focused around transit, and built with walkability in mind all adds up to a city where non-auto modes are easier for more trips; therefore they are the ones used by the public.

As a point of comparison (with the caveat that some of the statistics might not be exact apples-to-apples comparisons) to other places and other commutes. In Paris, France: 60% walking, 27% transit, 4% bike, 7% by car. Note that this appears to be all trips, not just commute trips. Also note that 60% of Parisians do not own a car. Add in the macro-level trends concerning the drop in vehicle-miles traveled, particularly among younger Americans.

For American cities, compare the state of the DC’s non-auto mode share to other American cities in the 2012 State of Downtown report from the Downtown Business Improvement District:

The difference between DC residents commuting and people commuting to DC is significant, but not as large as the difference between DC and the region as a whole – such are the benefits of ruling out most of the auto-dominant suburb-to-suburb commutes.

Likewise, the total non-auto share for DC residents stands at 55%. Getting to 75% is a good target, but certainly not unreasonable given the starting point. Brooklyn, for example, currently has a 75% non-auto mode share (60.8 transit; 8.7 walk, 3.9 work from home, 2.1 other = 75.5%).

Making up that 20-point gap is realistic; adding 250,000 new residents is similarly realistic. These goals are complimentary to one another.