$3\mathrm{.}191-96$ Incident and Queueing Analysis. A truck overturned at $11$:$57$ AM near milepost $138$ on NB $1-96,$ completely blocking that highway. Fortunately, the incident site is just beyond an overpass, between an off$-$ramp and an on$-$ramp. This means that most vehicles will see the blockage and exit $196$ at the off$-$ramp, avoiding a long backup and long delay. This also makes the detour of through vehicles simply a matter of using these ramps to go around the incident site. For the first $10$ minutes after the truck's misha, the ramp capacities were governed by the stop sign at the end of the off$-$ramp and the priority given to cross traffic, which did not have a stop sign.

The ramp's service rate for detouring traffic was approximately $325$ ph$.$ After $10$ minutes, state police began controlling traffic at the end of the off$-$ramp, increasing the ramp's service rate for detouring traffic to $650$ vph$.$ At exactly $1$:$00$ PM$,$ NB $1-96($capacity $-3600$ vph$)$ was reopened to through traffic. If the NB I$-96$ flow rate at this time of day is $1550$ vph: