I'm looking for literature about a variant of the capacitated vehicle/fleet routing problem (a.k.a. VRP, CVRP, etc.) that takes into account the possibility of handovers between multiple vehicles, i.e. the ability to drop off an item from a vehicle and let another one pick it up. Put otherwise, we could say we are allowing an item to be transported (sequentially) by more than one vehicle, e.g.:at time $T^u$ vehicle $V_1$ takes the item from the pick-up location $P^u$ at time $T^d_1 \geq T^u$ vehicle $V_1$ drops it off at an intermediate point $P_1$at time $T^u_1 \geq T^d_1$ vehicle $V_2$ picks it up from the intermediate point $P_1$ at time $T^d_2 \geq T^u_1$ vehicle $V_2$ drops it off at the intermediate point $P_2$ ... at time $T^u_{n-1} \geq T^d_{n-1}$ vehicle $V_n$ picks it up from intermediate point $P_{n-1}$ at time $T^d \geq T^u_{n-1}$ vehicle $V_n$ delivers it to the final destination $P^d$.In the VRP overviews I found this variant is not mentioned so I was wondering if anybody knew if it has been investigated at all. note: the term handover is something I came up with to describe the problem: it may not be the one commonly used to denote this kind of variant. The intended meaning, w.r.t. the example above is that e.g. when vehicle $V_1$ drops off the object $O_1$ at $P_1$ and $V_2$ picks it up we could say that $V_1$ hands over object $O_1$ to $V_2$ in $P_1$. update: Reworded to clarify that I'm talking about multiple vehicles (it was just kind-of implicit in the original wording). 
Capacitated multiple vehicle routing problem with handovers
ds.algorithms;reference request;graph theory;graph algorithms;optimization