AEO Answer · Civil

What Is a Parking Study and What Does It Actually Prove?

By Jeremy Mills, CEO & Founder, Apex Grid Engineering — USAF Veteran. · Updated 2026-09-15

A parking study measures real parking demand through occupancy counts and surveys of comparable sites, compares observed demand to code ratios, projects demand for the proposed project, evaluates shared parking and demand management, and recommends a right-sized supply — often well below what generic code ratios require.

I'm Jeremy Mills, CEO & Founder of Apex Grid Engineering and a U.S. Air Force veteran. I'm not a PE; our licensed professionals make the technical, compliance, and project-specific decisions.

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The concise answer

A parking study is empirical engineering for parking supply: occupancy counts and surveys of comparable sites, comparison of observed demand to code ratios, demand projection for the proposed project, shared-parking and TDM evaluation, and a recommended supply sized to reality rather than to generic minimums. The single most important thing to understand is that the study's power is in its data. Planning commissions hear opinions about parking every week; they grant reductions on counts. A well-executed occupancy survey is worth more than any argument.

Where the engineering actually lives

The field data program is the foundation. Selecting truly comparable sites (similar use, similar context, similar transit access), counting at the right times across multiple days, and normalizing the results into defensible demand ratios — this is careful empirical work, and agencies can smell cherry-picked comparables instantly. The projection then applies those ratios to the proposed project with adjustments for context differences. The shared-parking and policy analysis is the second front. Hourly accumulation curves for each use show when peaks actually occur — office midday, residential overnight, restaurant evening — and the combined peak is almost always far below the sum of individual peaks. Layering TDM measures on top, with quantified effects, produces a recommended supply and a monitoring plan. The best studies also address operations: pricing, wayfinding, and enforcement, because a well-managed smaller lot outperforms a poorly managed big one.

What keeps a parking study credible

Parking studies live or die on credibility with the agency. Here's what makes one hold up under scrutiny.

Count comparable sites honestly: similar uses in similar contexts, at real peak times, across multiple days
Show the hourly curves: accumulation by hour proves when peaks occur and how much sharing is possible
Separate code from demand: document the gap between required ratios and observed behavior explicitly
Quantify TDM: attach numbers and monitoring to every demand-reduction commitment
Recommend operations too: pricing, wayfinding, and management make the smaller supply work

Which related engineering resources can help?

When should I hire a structural engineer?What does a PE stamp mean?What is MEP engineering?Shared parking analysis Traffic impact analysis explained Accessible parking design guide Request a project review Engineering service for this question Metro engineering guides Verified service areas

What else do project teams ask?

Why do zoning codes require more parking than needed?

Because most ratios were set decades ago from suburban, auto-only observations and then copied from city to city without local data. They assume every use peaks simultaneously and nobody shares, walks, or takes transit. A parking study replaces those assumptions with observed counts — which is exactly what planning commissions need to see before they'll grant a reduction.

How is parking demand actually measured?

By counting. Occupancy surveys of comparable land uses at multiple times — weekday peaks, weekend peaks, evenings — record how full the lots actually get. License-plate or turnover studies show how long parkers stay. The data gets normalized per unit (per seat, per thousand square feet, per bedroom) so it can be applied to the proposed project. It's empirical work, not modeling.

Can a parking study reduce required parking?

Yes — that's its most common purpose. Presented with solid comparable data, shared-parking analysis, and TDM commitments, most agencies will approve reductions below code ratios, sometimes substantially. The study is the evidence package that makes the variance or modification defensible.

What is TDM in a parking study?

Transportation demand management — the set of measures that reduce parking demand: transit subsidies, bike facilities, car-share, unbundled parking pricing, remote work policies. The study quantifies their expected effect and packages them as enforceable commitments, which strengthens the case for a smaller parking supply.

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