According to the woman, what will most likely cause the traffic to be congested?

W: Aren’t you ready yet? We have to take off soon, you know. The rain out there is starting to really come down hard, and the traffic on the road is probably going to be chaotic.(50)
M: I know. Just give me a second. I have to take this paper up to Mr. Kim’s office before we take off.(51)Tell you what: why don’t I meet you in the lobby in five minutes? This way, I can go back to my office to get my coat as well.
W: All right, Bob, but hurry up, please. This is our first meeting with Mr. Rowe, and I don’t want to give him the wrong impression by being late.
M: Don’t worry. We still have plenty of time. Besides, we are going to take the subway, so you don’t have to worry about getting stuck in traffic.(52)