Amazon-ification and Vehicle Miles Driven

I visited my daughter Sara the other day and was amused to note that delivery services had dropped off two cardboard boxes in front of her house. When I stepped inside, there was a third box, still unopened. Three packages delivered in one day. Wow, thought I. My wife and I might average one delivery per week. Upon my further inquiries, Sara revealed that she also had begun ordering her groceries online and having them delivered to her doorstep as well.

Sara is the mother of a three-month-old infant, so running errands is a serious chore. I understand why she might be willing to pay a modest delivery fee in exchange for greater convenience, especially when she’s juggling baby care with handling the administrative work for her husband’s law practice.

There’s a lesson here for public policy. The rise of e-commerce and home delivery is changing America’s driving habits, especially among younger people less entrenched than carmudgeons like me in their customary way of doing things. Instead of driving to the grocery store and perhaps combining it with one or two other errands, such as depositing a check or picking up a prescription, more and more people are opting for online delivery.

Online-delivery option takes people like Sara off local streets and roads. In the argot of transportation planners, it reduces the number of trips per household. For decades, the propensity for Americans to take an increasing number of trips per day fed the increasing number of cars on the road. According to Federal Highway Administration data, the average number of trips per household increased from 2.3 in 1969 to 3.3 in 2009, and the number of daily vehicle-miles driven per household increased from 34 to 58.1.

Conversely, more e-commerce means there are more delivery trucks roaming around our metropolitan regions and dropping off more packages than ever.

Here’s a big question for public policy wonks: Are we as a nation experiencing a net gain in vehicle miles driven or a net loss as a result of e-commerce? My hunch is that the trend is bringing about a net reduction in driving. While the typical American stops at one or two retail/service locations on average for each trip, I’m surmising that delivery trucks are stringing together long chains of drop-offs, using computer algorithms to plot the shortest, most efficient routes. (This may be true even for grocery store deliveries by refrigerated trucks.)

In sum, I would expect the net result to be positive for society — fewer vehicle miles driven, fewer vehicle emissions, and less congested streets. (But more cardboard boxes in the landfill.)

While positive overall, one might argue, this trend does not help our biggest headache: rush hour congestion caused by people driving back and forth from work. But even here, I expect there will be a modest benefit from home deliveries. Working people typically tack errands onto their commutes home — picking the dry cleaning, stopping at the grocery store, whatever. Insofar as home deliveries displace those rush-hour errands and shift the trips to non-rush hour times of the day, they might alleviate rush hour traffic to a modest degree.

The truisms that have underpinned our transportation planning are shifting under our feet. Smart planners will take into account the impact of e-commerce and home deliveries before investing billions of dollars on new roads, highways and mass transit projects on the assumption that the trends of the past 30 years can be confidently projected into the next 30 years.