It is easy to assume that online shopping is ‘greener’ than physically visiting a store, but that may not be the case.

Crude logic suggests that if each individual shopper does not have to get in their cars and travel to a store one-by-one, the load on the road and on the environment would be reduced.

But a new multi-year regional study suggests that home shopping has a greater impact on the transportation sector than one might suspect.

“Our simulation results showed that home shopping puts an additional burden on the local transportation network, as identified through four measures of effectiveness - travel time, delay, average speed, and greenhouse gas emissions,” says research co-author Mingxin Li.

While online stores certainly require less space and use less energy, research leader Dr Arde Faghri points out that online shopping puts more delivery trucks on the roads.

This translates into more wear-and-tear on pavements and increased environmental pollution through the emission of fine particulate matter from diesel engines.

An additional problem is that residential and downtown streets were not designed to accommodate frequent truck stops, parking, loading and unloading, so trucks can interfere with through traffic, causing delays and compromising safety.

Faghri cautions that his study looked only at residential commerce, not purchases made by commercial and industrial businesses, and that the data his team collected (while detailed and covering several years of movements) was limited to the city of Newark, Delaware.

But he says that local, state, regional, and national planners should undertake similar efforts to keep an eye on the impacts of home shopping when planning and budgeting for infrastructure.

“The increase in online shopping also affects land use patterns such as the number and size of stores in large shopping malls with vast parking spaces, as well as changes in labour markets, with, for example, less demand for sales personnel and more for truck drivers,” he said.

Interestingly, But may be the most surprising finding of the study had nothing to do with increased truck traffic.

“We found that the total number of vehicles miles traveled hasn't decreased at all with the growth of online shopping,” Faghri says.

“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.”

The study appears in the International Journal of Sustainable Development and World Ecology.