Sustainable, climate-friendly transportation has a ghost in its machine: the trip not taken. In one sense, the trip not taken is literally a trip not taken – a drive from your house into town because you’re stringing your errands together. But in another sense, the trip not taken is actually a trip where you propel yourself – walking, biking, or any wheels with no motor. This is dropping your kid at daycare next to your office, or a commute that once was by car, but now is by bike.
These are trips in a strict sense, but not from a transportation planner’s perspective. And that causes some problems in quantifying the emissions reductions from biking and walking. In filling in the gaps on climate policy for transportation, we will need to consider how to measure how much people move around without motors and how to assess when a trip represents a mode switch.
People often talk about raising cycling or walking rates, but it’s not always clear whether these are car miles being offset. Cycling as an alternative to inconvenient transit doesn’t have the same emissions impact as cycling as an alternative to a trip made by car. Another pitfall is counting all cycling miles, including recreational miles.
The distinction of a cycling trip for recreation versus transportation is important for climate policy. If biking and walking miles increase, but car miles stay the same, then we’re still in trouble.
Big changes in the landscape are needed for roadways be more friendly to pedestrians and wheels with no motors. And it’s those kinds of changes that lead to people deciding maybe they don’t need a car anymore. Coupled with car sharing programs like Zipcar and Flexcar, motorized transportation can become a less-frequent need.
Lena Pons is a transportation policy analyst for Public Citizen.