Mathematical Model Revealed that Automated Vehicles Can Achieve 40-50 Percent Gains in Spatial Efficiency for Off-Street Parking Facilities.

Researchers Examined Capacity Impacts and Optimal Geometry of Single-Story Parking Lots with Automated Vehicles.

Date Posted

Capacity Impacts and Optimal Geometry of Automated Cars’ Surface Parking Facilities

Summary Information

Vehicle automation technologies have become more commercially accessible and their impacts on transportation systems more prominent in terms of capacity, land use, travel time, transit, safety, and parking. This study developed a nonlinear model to compare the spatial efficiencies of human-driven and Automated Vehicle (AV) surface parking facilities. Numerical results were provided considering a range of automated driving maneuvers, including single- and multiple-motion with front and reverse drive directions in parking space. In addition, hypothetical facility sizes ranging from 10,000 sq ft to 1,000,000 sq ft were considered in the analysis.


The study formulated a methodology based on certain premises to optimize parking capacity in single-story, obstruction-free parking lots with square or rectangular layouts. It assumed AVs of uniform size and capability, with impeccable localization and maneuverability, allowing each to be accessible without being blocked. The model required two access points for the lot, precluded the need for larger vehicle circulation, and assumed passengers would exit the parking space without the need for extra space to open doors. Maneuvers were restricted to tangents or fixed-radius arcs, with AVs allowed to briefly use opposing lanes for turns. All parking spots conformed to one size within double-loaded rows, and the boundary aisles supported two-way traffic. An optimization model was developed to maximize parking space. A ‘human small’ parking dimension was defined as parking space dimensions of 8.67′ width and 19.75′ length for low-turnover spaces, with a 25′ aisle-width, while a ‘human large’ was defined as a width of 9′ for high-turnover spaces, with the same space-length and aisle-width dimensions. 


  • The results regarding the change in spatial efficiency (the proportional change in parking capacity) comparing AV maneuvers against ‘human small’ parking space dimensions showed that efficiency gains range from seven percent to 44 percent.
  • The respective gains in efficiency relative to ‘human large’ parking spaces were estimated between 15 percent and 49 percent. 
  • Overall, it can be concluded that gains in the order of 40–50 percent in spatial efficiency (parking spaces per unit area) are potentially achievable.
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