How long it takes (1)/to travel from Chennai to Trichy (2)/ by train? (3)/ No error. (4)

Answer

1

Explanation

of an Interrogative Sentence starting with whords and How, the structure is as follows:
How long + do/does + subject +`V_1` or `V_1` + s or es + ...?
Look at the sentences :
How long does the train take to reach Mumbai from Delhi ? How long do you need to do this work ? Hence, How long does it take is the right usage.