trafficking的原形是哪個單詞

例句：

Traffic is bad, particularly in the city centre.

交通狀況很差，尤其是在市中心。

The traffic lights are controlled by a central computer.

交通信號燈由中心計算機控制。

I couldn't hear her above the noise of the traffic.

交通嘈雜，我聽不見她的聲音。