But zipping through the congestion is the vanguard of another transportation revolution: vehicles that use no gas, emit no exhaust and are so quiet they can surprise the unwary pedestrian.

• 但是在解决交通拥挤中是另一种交通革命的前导：这种交通工具不消耗汽油，没有废气排放，非常静音以致有时会惊动旁若无人的步行者。