A friend once told me of driving along a one-lane, unpaved mountain road.

一个朋友曾经告诉我，他驾车沿着一条没铺柏油的单行山路走。

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With so many new cars in the mix, average vehicle quality is far better than it used to be, so breakdowns on one-lane roads no longer trigger gridlock automatically, the way they once did.

他们认为，那么多车混杂在一起，车的平均质量要比以前好很多，所以即使车在单程车道上抛锚，也不会再像以前那样必然导致交通堵塞了。

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The road is only one lane wide.

这条路只有一个车道那么宽。

《柯林斯英汉双解大词典》

Last Friday, Mr. Smith drove his truck slowly down a one-lane road in search of the herd.

WSJ: Reviving Slaughter of Horses

Smaller two- and one-lane roads (designated as National or Regional roads) are also in the midst of an extensive rejuvenation project.

FORBES: The Last Roar of the Celtic Tiger

It was humankind that posed the final obstacle:Halfway through the park we encountered a vanload of tourists blocking the one-lane dirt road.

FORBES: Magazine Article