"春运"可谓中国专属，所以英译时可直接引用汉语拼音为"Chunyun"，也可以意译为"the Chinese Spring Festival travel rush(或season)","春运"英文介绍:
Chunyun refers to the extremely high traffic load of transportation in China around the time of Chinese New Year,which happens annually with millions of people rushing to their hometowns from where they work or study in order to catch up with the most important and special affair-family reunion.
上车补票一般都是会补到的，并不会被乘务人员赶下来，大部分情况下补票都是无座票，也就意味着没有座位的。不过需要注意的就是，如果在节假日出行，补票的人数比较多，为了避免列车出现超载的情况，此时可能就会无法补到车票，从而被赶下来。