Solving traffic problems by developing resilient roads

A new study suggests cities and regions should think about their whole network of roads as resilient rather than focusing on main arteries:

In a paper published Wednesday in the journal Science Advances, Maksim Kitsak, associate research scientist in the Department of Physics and Northeastern’s Network Science Institute, and his colleagues examine the resilience and efficiency in city transportation systems. Efficiency refers to the average time delay a commuter would face annually due to traffic. Resilience is the ability of road networks to absorb adverse events that fall outside normal daily traffic patterns…

“What we show is actually these two measures are not really correlated with each other,” Kitsak said. “One would think that if the city is bad for traffic under normal conditions, it would be equally bad or worse for traffic under additional stress events, like severe weather. But we show that is not quite the case.”

For example, the study found that the Los Angeles transportation network—while inefficient on a daily basis—doesn’t suffer much from adverse events. The road systems are resilient. They function more or less the same regardless of unforeseen incidents…

Why is the City of Angels more resilient than the City by the Bay? Kitsak said there are many factors that influence transportation resiliency, but one of the most important ones is the availability of backup roads. Los Angeles has many, while San Francisco does not. San Francisco also relies heavily on bridges, which separate the city from other parts of the Bay Area where many commuters live.

This is more evidence that simply adding lanes to major highways or even constructing more major roads is not necessarily the way to go to solve traffic and congestion issues. All the roads (plus other transportation options) work together in a system or network.

Speaking of Los Angeles, this reminds me that the region can illustrate both the good and bad of having a more resilient road network. On the good side, concern about potential Carmageddon and Carmageddon 2 were overblown as the closing of a major highway for repairs was not as disruptive as some thought. On the flip side, a few years ago some Los Angeles residents complained about Waze rerouting cars through their quiet neighborhood to avoid backups on the main roads.

Finally, this study could also be related to claims by New Urbanists that the best option for laying out roads and space is on a grid system. Grids allow drivers and other easy ways to get around problem spots. In contrast, subdivisions (common in suburban areas) that include quiet and occasionally winding residential roads that dump onto clogged main arteries do not contain many alternatives should something go wrong on the main roads.

So is the trick in the long run to create a resilient road network within a region that is not totally dependent on cars? Los Angeles might come up looking good in this study but not everyone would agree that sprawl and lots and driving is desirable.

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