• 12.19.11

Slow And Steady GPS Takes Longer, Saves Money

Using algorithms to calculate shortest routes and congestion, scientists have come up with a new GPS that gives drivers the most efficient route. Are people willing to drive a little longer to prevent emissions (and save money)?

There are lots of big ideas for making urban transportation less polluting–Build new subway systems! Switch to electric cars!–but most of them require correspondingly big investments of time and money. There is a simpler solution that would eliminate quite a bit of emissions, with hardly any cash outlay. What if everyone just took the most fuel-efficient route when they got in the car?


Two SUNY-Buffalo researchers, Adel Sadek and Liya Guo, recently examined the potential of this idea, which they call “green routing.” Sadek and Guo created a model of driving patterns in the Buffalo-Niagara region of upstate New York by combining one computer simulation tool called MOVES, which estimates motor vehicle emissions, with another called TRANSIMS, which simulates traffic.

They then tweaked the routes drivers traveled to find what they call “green-user equilibrium,” a point with the lowest total emissions. At this point of equilibrium, with everyone taking the most fuel-efficient route, overall carbon monoxide emissions were 27% lower than the status quo. That’s a significant reduction, especially considering that the transportation sector is responsible for roughly a quarter of all U.S. carbon emissions.

The most efficient route, of course isn’t the fastest route, however. In Sadek and Guo’s optimal model, emissions were lower in part because more cars were taking surface streets and fewer were on the freeways. That reduced traffic, meaning less stopping and starting, but it also made trips longer–by 11% on average. Are people willing to sacrifice a few extra minutes on their commute twice a day in order to save 27% of their emissions?

It’s highly unlikely. While a frugal few might be happy to use green routing to save a few bucks a month in gas bills, in the real world, you can’t just tell people to take a slower, more efficient route and have them do it–people don’t behave that rationally. Still, research like this might help a local municipality or a company like Google give drivers the option, or help a large fleet, like a delivery service, save a bundle when it’s used by thousands of trucks a day. The greenest route is, after all, also the cheapest route.