Maybe online shopping isn’t so green after all

On the surface, shopping online seems like it would be good for the environment: it eliminates car trips and their associated carbon emissions because people no longer need to drive to stores.

But what about the emissions from fleets of delivery vehicles bringing orders to houses? Delivery trucks also contribute substantially to the burden of fine particulate matter, known as PM2.5, in the air, which is associated with many effects on human health.

Relatively little research has thoroughly traced the effects of online shopping on transportation networks. But a recent study in Newark, Delaware suggests that the knock-on effects of online shopping may worsen traffic congestion and transport-related carbon emissions.

Researchers at the University of Delaware conducted a survey of downtown Newark residents’ shopping habits and preferences and used the responses to calculate the quantity of goods purchased through home shopping.

They also got information from delivery companies about the number of trucks on the road and the number of packages per truck, and used this to determine how many delivery trucks are required to distribute home shopping purchases.

Finally, the researchers used transportation simulation software and data from local transportation authorities to determine the effect of delivery trucks on the transportation network, focusing on an area of downtown Newark that includes a portion of the university’s campus.

They conducted similar analyses in 2001, at the dawn of the online shopping era, and again in 2008. They reported their results in a recent paper in the International Journal of Sustainable Development & World Ecology.

Curiously, the 2008 data suggested that home shopping in Newark had grown by only 14.8% since 2001. That’s much less than the researchers predicted in their earlier study. It also contrasts with data from other researchers showing that Internet shopping increased six-fold between 2001 and 2011.

The researchers don’t offer any explanation for their unexpected finding. However, a large proportion of their survey respondents were university students, and the convenience of Internet shopping may appeal more to people who are running a household.

Also, it’s significant that the researchers’ latest data are from 2008, which suggests that if anything their study underestimates the effect of home shopping on the transportation network.

In any case, the researchers found that even though home shopping by residents of Newark grew more slowly than anticipated, traffic in 2008 was worse than they had predicted.

An increase in the number of home shopping purchases increases travel time, traffic delays, and vehicle emissions of the transportation network as a whole, the researchers say.

While some previous studies suggest that e-commerce is associated with lower carbon emissions than traditional retail, other researchers have warned of a “rebound effect,” which occurs when gains in efficiency merely stimulate new consumption. Something similar may be going on in Newark, the results suggest.

“We found that the total number of vehicles miles traveled hasn’t decreased at all with the growth of online shopping,” says study leader Arde Faghri, professor of civil and environmental engineering and director of the Delaware Center for Transportation. “This suggests that people are using the time they save by shopping on the internet to do other things like eating out at restaurants, going to the movies, or visiting friends.” – Sarah DeWeerdt | 16 February 2016

Source: Laghaei J. et al. “Impacts of home shopping on vehicle operations and greenhouse gas emissions: multi-year regional study.” International Journal of Sustainable Development & World Ecology DOI: 10.1080/13504509.2015.1124471

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