I am building a national transportation model ( a bit different than a normal DES model) for a company that transports good from the RDC to its sites. A request comes in for a truck to transport the goods to different sites, so I use a destination list in my tranporter to travel to its correct destination and when it has delivered the last item it returns to the RDC. The company uses its own dedicated fleet as well as sub-contractors, but its own fleet gets priority. When a request is received my current model checks to see if a truck is available and if it is then that truck gets allocated to the request. When a truck is not available a sub-contractor truck is created and is allocated. This however is not correct. My model has to check where my dedicated trucks are at the time in my model and then determine if a truck can come back in time to pickup another load and deliver it (we only want to use our own fleet but we also have a 2 day delivery policy). If not then we make use of a sub-contractor.
What I want to know is how can my model check where my trucks are and how long it will be before they are back at the RDC to transport another request.