"Can road capacity expansions provide a solution to traffic?" (Hint: data says no)
From the paper's abstract:
Building more roads is a commonly employed policy intervention to reduce congestion. This strategy, however, is controversial because under certain conditions road capacity expansions may induce growth in traffic volumes. A crucial precursor to understanding whether road capacity expansions provide a solution to congestion is to quantify the technology driving congestion in urban road networks. This congestion technology describes the variation in performance of the network, often represented by traffic flow through the road network, over its intensity of use given by the number of vehicles in the network.
A blog post on the State Smart Transportation Initiative looks at the study and shares a quote on the findings:
Our results suggest that capacity expansions do not lead to substantial changes in the average travel speed in the network. Thus, building more roads in major urban areas may create more congestion, pollution and collisions. Moreover, such policies may also increase the other wider negative consequences of vehicular travel such as global warming and climate change as they allow more mobility for urban residents.
And then they finish with their own thoughts:
They note that some targeted capacity expansions are inevitable, but other congestion management strategies like operational improvements, congestion pricing, and parking management could be more beneficial.
Finally, they add that while roadways become less efficient as the density of users increases, literature overwhelmingly suggests the opposite is true for rail and bus networks. "Thus," explain the authors, "public transport services are potentially more productive and cost-efficient compared to vehicular travel in dense city centres."
This study, while novel in its approach, only adds to the evidence and general understanding of induced demand, which more transportation agencies are recently coming to terms with.
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There was a surge in road deaths during Covid, why?
From the Abstract:
Despite a brief reduction during the initial months of the COVID-19 pandemic, the number of people killed in motor vehicle crashes in the United States surged in 2020 to its highest level in over a decade. The purpose of the research reported here is to advance the understanding of how safety on U.S. roads changed during the pandemic, beyond its initial months, by comparing the involvement of specific crash-, vehicle-, and driver-related factors in fatal crashes during the eight-month period of May through December 2020 to what would have been expected had the pandemic not occurred and pre-pandemic trends continued. [...] Overall, the number of traffic fatalities in 2020 was 2,570 (7.1%) more than expected based on pre-pandemic trends. However, a sharp decrease in traffic fatalities in March and April 2020 partially offset an even larger increase later in the year. During the eight-month period of May through December 2020, the number of traffic fatalities was 3,083 (12.1%) more than expected.
The real takeaway:
The increase in traffic fatalities was not uniform across crash-, vehicle-, and driver-related factors. Scenarios present in greater than expected numbers in fatal crashes in 2020 included evening and late-night hours, speeding drivers, drivers with illegal alcohol levels, drivers without valid licenses, drivers of older vehicles, drivers of vehicles registered to other people, crash involvement and deaths of teens and young adults, and deaths of vehicle occupants not wearing seatbelts. In contrast, several crash types followed pre-pandemic trends (e.g., crashes in the middle of the day; crash involvements of drivers with valid licenses; pedestrian fatalities), and a few decreased (e.g., crashes of elderly drivers; crashes during typical morning commute hours).
So what we saw was an increase in deaths in the middle of the night, midday crashes held, and crashes by elderly or in the morning.
I am curious to find out any data relating to crashes based on economic situations. I suspect we would find workers of lower incomes suffered much of the reported spikes.
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