What is the difference between 拥堵 and 堵车?
The main difference between 堵车 and 拥堵 is that 堵车 is usually used as a verb, while 拥堵 is usually used as a noun.  For example,  前面堵车了 and 前面交通出现了拥堵; 防范交通拥堵, not 防范交通堵车;