In the centre of the hall, there were a number of tall structures which contained coloured lights. These lights flickered continuously like traffic lights which have gone mad.
Why use ‘have’ there? I feel that using ‘had’ is better way. Am I right?
The word have occurs in a clause beginning with like, which indicates that it is a simile - something that is not directly related to the actual situation. When providing a simile, it is not necessary for the time frame of the simile to be the same as the time frame for the actual situation. It is therefore perfectly reasonable to use present perfect in the simile when past perfect would be the correct tense for the real situation.