When you walk on a sandy beach, it takes more energy than striding down a sidewalk—because the weight of your body pushes into the sand. Turns out, the same thing is true for vehicles driving on roads.
“The weight creates a shallow indentation or deflection in the pavement, and makes it such that it's continuously driving up a very shallow hill.”
Jeremy Gregory, a sustainability scientist at M.I.T. His team modeled how much energy could be saved—and greenhouse gases avoided—by simply hardening the nation’s roads and highways.
And they found that stiffening 10 percent of the nation’s roads every year could prevent 440 megatons of carbon dioxide equivalent emissions over the next five decades—enough to offset half a percent of projected transportation sector emissions over that time period.
To put those emissions savings into context—that amount is equivalent to how much CO2 you’d spare the planet by keeping a billion barrels of oil in the ground—or by growing seven billion trees—for a decade.
The results are in the Transportation Research Record. [Hessam AzariJafari et al., Potential contribution of deflection-induced fuel consumption to U.S. greenhouse gas emissions]
As for how to stiffen roads? Gregory says you could mix small amounts of synthetic fibers or carbon nanotubes into paving materials. Or you could pave with cement-based concrete, which is stiffer than asphalt. (It’s worth noting the research was funded in part by the Portland Cement Association.)
This system could also be a way to shave carbon emissions without some of the usual hurdles.
“Usually, when it comes to reducing emissions in the transportation sector, you’re talking about changing policies related to vehicles and also driver behavior, which involves millions and millions of people—as opposed to changing the design of our pavements. That’s just on the order of thousands of people who are working in transportation agencies.”
And when it comes to retrofitting our streets and highways—those agencies are where you might say the rubber meets the road.
—Christopher Intagliata
[重難點詞匯、短語]
stride: v. 大步走，闊步行走，跨越；n. 大步，步態shave: v. 削減retrofit: v. 加裝（新設施）when the rubber meets the road: 理論付諸實踐，觀點得以檢驗
[參考譯文]
在沙灘上行走會比在人行道上大步走需要更多的能量，因為你的身體重量會陷入沙子里，事實證明，在道路上行駛的車輛也是如此。
“重量會讓路面淺淺地凹陷下去或造成一定偏斜，讓車處于一種不斷爬升小淺坡的狀態中。”美國麻省理工學院（MIT）可持續發展學家杰里米·格雷戈里（Jeremy Gregory）說道，他的團隊通過模擬探究了簡單地加固道路和高速公路可以節省多少能源、減少多少溫室氣體排放。
他們發現，每年加固全美國10%的道路，就可以在未來50年內防止440兆噸二氧化碳當量的排放，這足以抵消同一時期內交通運輸部門預計排放量的0.5%。
如果把這樣的減排量換算成環境效應，它相當于10年間在地下儲存10億桶石油或種植70億棵樹所能為地球補償的CO2。
研究結果發表在《運輸研究記錄》（Transportation Research Record）上。
至于如何加固道路？格雷戈里說，可以將少量合成纖維或碳納米管混合到鋪路材料中，或者也可以用比瀝青更硬的水泥基混凝土鋪路。（值得注意的是，這項研究部分由波特蘭水泥協會資助。）
相對來說，這種方式可能是一種不會遇到常見阻礙的減排方法。
“當談到減少交通部門的排放時，我們常說的是改變與車輛和駕駛員行為相關的政策，而不是改變我們的道路設計，前者涉及到的人數以百萬計，而后者只涉及在運輸機構工作的數千人。”
當談到改造我們的街道和高速公路時，這些機構就是將理論付諸實踐的重點了。
原文鏈接：https://www.linkresearcher.com/careers/c4030e6b-d749-478a-b166-432b356c7c41