After six years and $1.6 billion, the expanded version of Los Angeles’s I-405 has opened. Its new car pool lane, on-off ramps and three earthquake-proof bridges are supposed to cut commute time for 300,000 drivers. Do they? Afternoon traffic is better while rush hour is worse.
We might have a similar story in Texas. Between Dallas and Fort Worth, they spent $425 million on repaving along a 6.3 mile stretch. The goal was to eliminate a bottleneck by opening the shoulders to traffic during rush hour. Were they successful? Maybe. When the road opened there was less congestion. However, many believe that the relief is temporary.
Where are we going? To successful infrastructure spending.
It is possible that more lane miles encourage more driving. So, if your goal was to reduce congestion, adding roads might not be the solution.
In one study roads scholars estimated that by the fourth year, traffic is way up:
Viewed from a supply side lens, municipalities might just be doing some good planning when they increase lane mileage. After all, if they expect that population will grow, more road capacity makes sense:
And here, it gets even more complicated as the variables multiply. Below, we add economic development along the road to the model. Furthermore, speedier arteries bring the suburbs closer to the city:
Our Bottom Line: Tradeoffs
Infrastructure spending takes us to three stages of economic analysis.
- First infrastructure spending is an idea that can influence private sector investing.
- Next, we have a the cost and benefit of a construction phase. At this point dollars, time and inconvenience can be our focus.
- And finally, a completed project is about demand and supply. On the demand side for roads, the variables range from elasticity (miles used/miles built) to the demand that is induced by its creation. Equally crucial, on the supply side we have industrial and retail development.
So, when our new president refers to infrastructure spending on roads, he is really talking about countless economic ideas that let us judge the tradeoffs. Only then can we decide if more driving capacity makes sense.
My sources and more: A perfect starting point is these Washington Post maps in which they show us an infrastructure beyond our roads. Moving from general to specific, next we can look at two projects. The NY Times had the California road story and Wired, the Texas project. And, we can assess those projects with analysis from the UC Berkeley transportation Institute here and here. Although the Berkeley article was from 1995, it is still relevant and complements this article about ramp entry.