## 3 Factors for Choosing Optimal Parking Spaces  
In an automated valet parking system, AVs are assumed to be able to interface with the central command station in an intelligent parking infrastructure. However, under the scenario in which there are both HVs and AVs in a parking infrastructure, no matter how intelligent the parking infrastructure is, the central command station cannot allocate parking spaces for the HVs which are not equipped with any communication devices. Based on this scenario, we consider the problem of a HV looking for a parking space in an intelligent parking infrastructure when an AV enters at the same time. The central command station, before allocating a parking space for the AV, must predict which parking space that the driver of the HV would choose and then allocate one of the remaining parking spaces to the autonomous vehicle. When a driver enters a parking infrastructure, his choice of parking space is often affected by his perception of various factors in the parking environment. [PERSON] et al. [25] proposed six major factors that influence drivers to choose parking spaces: the walking distance from the parking spaces to the exit of the parking facility, the distance to the parking space from the entrance, the status of the path to the parking spaces, the status of the available parking spaces, parking safety, and shade under sunlight when parked outdoors. Since parking safety is somewhat implied in the status of the path for the AVs and the test case considered in this paper (see Section 6) is an outdoor parking lot with no shaded area, the last two factors will not be discussed in this paper. Thus, this paper focuses on the following four factors. * _Walking distance_ Walking distance is the distance between the parking space and the exit of the parking infrastructure. For drivers, they likely prefer to arrive at their destination as quickly as possible after parking. Therefore, the shorter the walking distance, the more likely the parking space will be chosen. * _Distance to parking_ Distance to parking is the distance between the entrance of the parking infrastructure and the parking space. For drivers and occupants, they generally prefer to arrive at their vehicles as quickly as possible, particularly when they forget something (e.g., phones, wallets) or need to place something back in the vehicle. Therefore, the shorter this distance, the more likely the parking space will be chosen. * _Status of the path to the parking spaces_ Vehicles that break down (e.g., dead batteries) may block the path to some available spaces. Generally, lanes in parking infrastructures are narrow and often only one vehicle can pass through the lane. Lane occupancy increases traffic congestion and reduces traffic efficiency in the parking infrastructure. Thus, drivers are concerned with the status of the path leading to the available parking spaces and will likely choose those parking spaces that have clear paths. * _Status of available parking spaces_ [PERSON] [26] hypothesized that, in general, particularly new drivers are more inclined to choose available parking spaces with spaces on both sides unoccupied. The order of the priority of choice is followed by those spaces with one adjacent space unoccupied, those adjacent to the road, and finally those with spaces on both sides occupied. Characteristics of parking spaces can be grouped into two main types: the cost type and the benefit type. For the four factors mentioned above, walking distance and distance to parking are cost types. Status of the path lane to parking spaces and status of available parking spaces are benefit types. The lower the value of the cost type factor, the higher the priority of the parking space would have. Contrarily, the higher the value of the benefit type factor, the higher priority of the parking space. Walking distance and distance to parking can be described by measurable values based on the layout of the entire parking infrastructure.