Problem $2.$ The following time$-$space diagram shows boats traveling on a two$-$way water canal with locks.

$-$space diagram

for boats on a canal. Source: Schultz, R$.$ P$.(1967)$ Graphic analysis of waterway capacity. Journal of the Waterways and Harbors Division $93,177-184.$

For the duration of time shown on the diagram, how many upbound vessels traverse all $11$ miles of the canal?

For the duration of time shown on the diagram, how many downbound vessels traverse all $11$ miles of the canal?

What is the impact of the $"$no passing" zones on the downbound vessel movements? $($What is happening at points $($g$)$ and $($h$)$ in the diagram?$)$