Traffic Idioms (American idioms)
美 式交通的慣用語

rush hour 


explanation :  This popular idiom refers to the time of day when traffic is at its worst.  This is usually from 7:00 ~ 9:00 am, when people are on their way to work, and 5:00 ~ 7:00 pm, when people are on their way home.  'Rush hour' can often be more than one hour.  The idiom refers to the fact that everyone is trying to 'rush' home or to work.  The common meaning of 'rush', to move quickly, is reversed in this idiom.  During 'rush hour' the traffic moves slowly.  

e.g.  Make sure to leave the office before rush hour, or you'll never get home before 8:00 pm.