There are several reasons why widening highways is usually a futile strategy to combat traffic congestion. For one, highway widening projects are costly and time consuming. It has also been well documented that adding new capacity to highways creates induced demand, which essentially means it will generate more traffic on the road. Consequently, over time the widened highway gradually fills up with additional traffic until it reaches a threshold, and is congested again. Of course, just the principle of widening highways is flawed because it encourages driving, it’s unsustainable, and it raids funds for other major transportation projects that are much more sustainable, such as transit. However, research from the Sightline Institute points out that widening highways also leads to substantial increases in GHG emissions in the mid-to-long term.
Conventional dogma preached by road-widening enthusiasts claims that additional capacity will decrease GHG emissions by easing traffic congestion. According to Sightline, this limited benefit only holds true in the short term, if at all. In the medium-to-long term, however, adding one mile of new highway lane will result in an increase in CO2 emission by more then 100,000 tons over 50 years. To quantify that, at current rates of emissions, 100,000 tons of CO2 equals the 50-year climate footprint of about 100 typical U.S. residents.
Image: Sightline Institute
If you enjoyed this article, please consider sharing it!
