1PHRASAL VERB (交通)形成塞车长龙,堵塞 When traffic tails back, a long line of it forms along a road, and moves very slowly or not at all, for example because of road works or an accident. (交通)形成塞车长龙,堵塞 [British]
Southbound traffic tailed back for twenty miles on the M5 near Bristol. [VERBPREP.]