The Fuse

Study: Online Shopping Adds to Congestion, Strains Transportation Sector

by R. Kress | February 18, 2016

Most home shoppers choose to purchase products online because it’s convenient. One click and almost any item can be delivered directly to the shopper’s home. While at first glance it may seem that home shopping has the added benefits of keeping cars off the road, reducing fuel consumption and the lowering the overall burden on transportation infrastructure, a new study finds that the opposite might be true.

Home shopping is nothing new: Consumers have used paper catalogs and phone purchasing methods for years. But with online shopping growing year after year, Arde Faghri, Director of the Delaware Center for Transportation and professor of civil and environmental engineering at the University of Delaware, led a new study to learn exactly what impact our home shopping habits are now having on the transportation sector.

“People are ordering more items online but at the same time their vehicle miles traveled (VMT)—the amount of mileage that one puts on their vehicle—has not decreased,” Faghri tells the Fuse. “So it seems like by ordering online, you increase the numbers of trucks on the roadways and simultaneously, in terms of VMT, you’re putting the same amount of mileage on the roadways as you used to.”

In his research of national VMT data, Faghri found that the only time numbers dipped was when gas prices approached four dollars per gallon several years ago. When gas prices are stable or dropping as they are now, Faghri says that people will put a relatively constant number of miles on their cars even if they’re saving themselves the travel time of shopping trips.

“What we noticed is that people order things online but their mileage behavior hasn’t changed. Maybe they forego driving for shopping for books or airline tickets or toys but they use that saved time to [drive to] other things that perhaps they didn’t before,” Faghri says.

Faghri’s multi-year study called “Impacts of Home Shopping on Vehicle Operations and Greenhouse Gas Emissions” has just been published in the International Journal of Sustainable Development and World Ecology. He found that since 2001, an increase in home shopping has placed added burdens across four key measures of the transportation sector’s effectiveness: travel time, delays, average speed and vehicle emissions.

Faghri is concerned that the country’s transportation infrastructure is not prepared to handle the burden of heavy delivery trucks making frequent visits to residential neighborhoods.

Using the city of Newark in Delaware as a test case, Faghri and his co-authors surveyed local residents about their home shopping habits—including purchases made online, from catalogues, by interactive television, and by phone. With a similar 2001 survey in hand by way of comparison, Faghri discovered that home shopping habits within the city of Newark had only increased by about 14.8 percent over the past 14 years. However, despite this relatively small increase in home shopping, Faghri and his researchers found that travel time, delays, average speed and fuel consumption had all worsened significantly—far beyond what earlier studies had forecast as worst-case scenarios expected with even greater predicted home shopping usage.

But in addition to his study’s findings on the increases in congestion and VMT, Faghri is concerned that the country’s transportation infrastructure is not prepared to handle the burden of heavy delivery trucks making frequent visits to residential neighborhoods.

“I’m a civil engineer. My job is to design and construct roads. But the traditional way of thinking of design and the codes that we still use—we have to be realistic. They’re no longer valid,” Faghri explains. “Trucks are heavy and they’re everywhere. When we designed our pavements 20 years ago, we had one set of standards for the freeway and another for arterials and another for local and neighborhood streets all depending on the weight exerted on the roadway. Now we have to make our pavement much stronger. If we don’t, we’re going to have to pay a lot more for maintenance.”

But what if one shopper goes to a site like Amazon where he can purchase a litany of items that would never be available in a single store on one driving trip—items ranging from dog food to diapers to a snow shovel? Those items might then be delivered by a single delivery service that can bring everything in a single run—a FedEx, UPS or USPS type of service that is not directly contracted by the seller. Faghri notes that, in these cases, some of the impact on the transportation sector might then be mitigated as one truck can do the work of many.

But Faghri sees the solution to this problem as a complicated one requiring several layers of changes especially is it challenges multiple areas: Road congestion, weight of trucks on local pavement, and fuel efficiency.

“Problems like this should have a multitude of different approaches. Amazon has been considering drones for a while now,” Faghri says. “I think drones are a very, very realistic alternative to truck delivery.”

In the meantime, however, Faghri cautions that home shopping—and online shopping in particular—is not going anywhere and will only continue to grow. As a result, urban and road planners should take this new reality into consideration and build accordingly.

“It’s a fact of the 21st century and we do need to take that into consideration when we are planning, designing and constructing our roadways. Urban streets, neighborhood streets, local streets—they were not designed for the amount and the weight that these heavy trucks are exerting on the pavement, or to have trucks stop right in front of their entry for 15 to 20 to 25 minutes during rush hour.” Faghri says. “We didn’t take that into consideration. But now that we have those numbers, maybe we should.”

Faghri also adds that alternative fuels and hybrid electric trucks could resolve some of the fuel consumption challenges associated with increased home shopping—but this change alone would not be able to mitigate impact on pavement and congestion.