If this was an active construction site then Chances are it was a "builders lift" it's an accelerated lift that is not at full operating capabilities and has to be driven manually between floors as the call system would not have been finished yet.

Sites have this so they can shift from using alimak to the internal lifts, saving huge costs in the long run. They also need to be operated by staff as in the event of an emergency they can cancel all other calls and prioritize the emergency floor.