Traffic is moving on a $6$-lane dual carriageway road. Traffic volume per direction during peak hour ($08:00$ am to $09:00$ am) is $6000 \mathrm{~veh} / \mathrm{h}$. It is assumed that the traffic is distributed uniformly across the lanes in each direction. Just at $08:00$ am, a truck goes out of order on the middle lane of one side, thus disrupting the traffic on that lane in one direction. The lane capacity under normal conditions is $2000 \mathrm{~veh} / \mathrm{h} / \mathrm{ln}$ and under queue formation it is $1600 \mathrm{~veh} / \mathrm{h} / \mathrm{ln}$. The traffic resumes at $08:30$ am on removing the truck from the middle lane. Hourly traffic volume after $09:00$ am reduces to $5000 \mathrm{~veh} / \mathrm{h} / \mathrm{dir}$.
The number of vehicles in the queue at $10:00$ am is $\_\_\_\_$ (in integer).
