Shared Parking: Definition and How It Cuts Spaces

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.

Illustrative: because uses peak at different hours, a facility they share needs fewer spaces than the sum of each use’s peak, the core of a shared-parking study. Concept: ULI/ITE Shared Parking.

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.

Try it

Share the garage

An office, a restaurant and apartments sit on the same site. Their parking peaks at different times of day. Turn uses on and off to see how many spaces one shared garage needs compared with separate lots.

Sized separately for their own peaks, a 300-car office, a 120-car restaurant and 200-car apartments need 620 spaces. Because the office peaks at midday, the restaurant in the evening and the apartments overnight, one shared garage needs about 470 spaces, 150 fewer, worth about $4.5 million in construction at $30,000 a space.

Illustrative weekday hourly profiles in the spirit of the ULI Shared Parking model; $30,000 a structured space. A real shared parking study uses local data, weekend and seasonal peaks, and a safety margin.

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.