Pavement design in Los Angeles County generally follows Caltrans standards and industry guidance from the Asphalt Institute and the American Concrete Institute, adjusted for local traffic and soil conditions. Caltrans pavement design manuals specify that thickness should be based on factors such as traffic loading (expressed as equivalent single‑axle loads), subgrade strength, and climate rather than a single “rule of thumb.” In practice, many designers in Southern California use local geotechnical investigations and Caltrans or AASHTO design methods to select thickness.
For light‑duty parking lots serving passenger vehicles, Asphalt Institute guidance and West Coast contractor specifications commonly recommend 2. 5–3 inches of hot mix asphalt over 4–6 inches of compacted aggregate base, assuming a relatively strong subgrade. For medium to heavy‑duty lots (serving delivery trucks, trash trucks, or industrial traffic), sections often increase to 3–4 inches of asphalt over 6–8 inches of base, or more, with localized thickening in drive aisles or truck routes.
The Los Angeles County Public Works standard plans and many city standard drawings (such as those from City of Los Angeles Bureau of Engineering) provide typical cross‑sections for parking areas, driveways, and alleys, including minimum base and asphalt thicknesses, compaction requirements (often 95 percent relative compaction per ASTM/Caltrans test methods), and drainage slopes. Where portland cement concrete is used instead of asphalt, ACI and PCA (Portland Cement Association) design tables guide slab thickness, often in the range of 4–6 inches for light duty with properly designed joints. In all cases, the design should be adapted to actual truck loading patterns, soil report recommendations, and local jurisdiction details rather than relying on generic national templates.