Shared parking is the practice of letting two or more land uses with different peak times use the same pool of parking spaces, so the combined supply is sized to the combined peak rather than to the sum of each use’s separate peak.
An office building fills its lot on weekday afternoons; a restaurant and cinema fill theirs on evenings and weekends. Built separately, each needs its own peak supply. Shared, they need only enough for the hour when combined demand is highest. The professional standard for the analysis is the shared parking method published by the Urban Land Institute (ULI), now in its third edition, which models demand hour by hour and month by month for each land use.
How a shared parking analysis works
- Base demand. Start with parking ratios for each use, separated into visitors and employees.
- Adjustments. Reduce for transit, walking and rideshare (the driving ratio), and for captive visitors who are already on site for another use (the non-captive ratio).
- Time of day and season. Apply hourly and monthly presence factors for each use.
- Combine. Add the uses hour by hour. The highest combined hour sets the design supply.
What it saves
- In a mixed-use district, a shared supply is commonly 10 to 30 percent smaller than the sum of separate requirements, depending on the mix of uses.
- Savings require the spaces to be genuinely shared: not reserved, not gated by use, and within walking distance of every use they serve.
- Many zoning codes allow shared parking reductions, sometimes with a required study. See parking ordinances.
The Parkonomics view
Shared parking is the cheapest parking space there is: the one you do not build. It works only when management matches the math. If spaces end up reserved, gated or priced separately by use, the overlap disappears and the shortage arrives on the busiest day. Write the operating plan into the approval.
Related terms: Parking Demand Analysis, Parking Ratios, Peak Demand, Urban Land Institute, Effective Supply