This domain has drivers that can walk between locations and trucks that can drive between locations. Walking requires traversal of different paths from those used for driving, and there is always one intermediate location on a footpath between two road junctions. The trucks can be loaded or unloaded with packages (with or without a driver present) and the objective is to transport packages between locations, ending up with a subset of the packages, the trucks and the drivers at specified destinations.
This domain was produced to explore the power of STRIPS solutions to transportation problems when the transportation involves a sub-problem of acquiring a driver. The problem is one that offers significant opportunity for concurrency in the use of drivers and vehicles, so we were also interested to see how the temporal variants were handled.
The metric variant of the domain adds costs for walking and driving and problem instances required that the planner optimise some linear combination of the total walking cost and the total driving cost.
The full temporal variant makes time spent driving or walking between locations dependent on the path being traversed, but other durations are only dependent on the actions (as with the simple temporal version). In both of these variants the plan quality depends on the make-span.
An additional variant, the hard numeric variant, complicates the cost of driving by making it dependent on the load being carried: each additional package added to a truck increases the fuel consumption rate of the truck by its current value, making the consumption increase as a quadratic function of the load.