a vehicle energy harvester including a subunit having an upper surface forming a roadway surface ; a vehicle activated treadle on the subunit , the vehicle activated treadle moveable between a first position in which an upper surface of the treadle is at an angle with respect to the upper surface of the roadway surface and a second position in which the upper surface of the treadle is flush with the upper surface of the roadway surface ; a generator that generates power in response to movement of the vehicle activated treadle ; and a treadle locking device that selectively locks the vehicle activated treadle in the second position .