I'm working with a sort of pickup delivery problem right now.

We need to assign vehicles to routes and requests to those vehicles. Each request has its due date, client and may be delivered in one of multiple possible trips departing from depot time windows.

The routes are predetermined, so we don't have routing decisions! This part is giving me a headache, since it looks more like an assignment problem but with many features of routing problems. I am quite lost...

Any suggestions on benchmark problems to look after?

Edit by suggestions of Ruslan for better explanation

By predetermined routes, I mean that the sequence of clients that a vehicle will visit is already known (ex.[2,3,5,6]).

The depot time windows are operational constraints meaning when we can start loading the vehicle with cargo and the maximum amount of time available for loading.

It's not necessary to have a vehicle assigned to every trip, only if a delivery is performed.

A solution structure example:

3 routes, 2 trips for each

trips = [trip1, trip2, trip3, trip4...]

Total clients = [1,2,3,4,5,6,7,8,9,10]

vehicles = [v0,v1,v2,v3]

requests = [r1, r2,...]

|Trip   |time window |vehicle|Clients       |Requests delivered |
|:-----:|:----------:|:-----:|:------------:|:-----------------:|
|trip 1 |  [t1,t2]   | v1    |[2,3,5,6]     |  [r1, r2, ...]    |
|trip 2 |  [t3,t4]   | v3    |[2,3,5,6]     |  [r, r, ...]      |
|trip 3 |  [t5,t6]   | none  |[4,1,7]       |       --          |
|trip 4 |  [t7,t8]   | v2    |[4,1,7]       |  [r, r, ...]      |
|trip 5 |  [t9,t10]  | v0    |[10,8,9]      |  [r, r, ...]      |
|trip 5 |  [t9,t10]  | none  |[10,8,9]      |       --          |