The purpose of this excerpt is that It speaks about the setting of the play.
Step-by-step explanation:
The three liens are extremely economical at setting up the situation for the rest of the play here. The lines first convey that the parents are enraged and that the children are at fault. It also shows that they cannot do anything about it.
The last line deftly tells the audience that they are going to be stuck in traffic for 2 hours effectively making them struck in the same situation for the duration.
This becomes the setting of the play by introducing the main conflict and the time frame of it.