Problem $1$: Incident Impact Analysis $($Shock wave analysis$)$

On a section of freeway, an accident occurs at $10$:$00$am at point B$.$ First, both lanes are blocked, then after $15$ minutes, one lane is cleared.

Traffic Sensor Data:

A: $q=2700vph,u=55m\frac{i}{h}$

B: one$-$lane open with $q=1500vph,u=4\mathrm{.}5m\frac{i}{h}$

B: two$-$lane open with $q=3600vph,u=40m\frac{i}{h}$

$k_{\text{j}\text{a}\text{m}}=480ve\frac{h}{m}i$

Question

By what time $(T_3)$ must the second lane be cleared to avoid the impact from the accident extending to $A?$

Please answer questions $5$ and $6$ as shown in the image