既可表示可数也可以表示不可数。表示交通这个大概念时为不可数名词。eg、 the government invest a lot to improve the transportation。表示不同的交通方式时为可数名词。

拓展

transportation和traffic的区别

traffic主要指交通（状况）即流动中的车辆或行人。如Many residents in beijing are likely to welcome efforts to improve traffic;transport 是具体意义上的运输、运送。如He often has boxes of samples to transport / Transport (交通工具）has long been scarce;transportation是抽象意义上的运输。如Even the transportation networks are maintained by farms、另transport是可数名词，transportation是不可数名词。