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Parking Supply and Demand Analysis
A Transportation Impact Analysis (TIA) for the City of Honolulu must include a parking analysis under two conditions: if a project proposes the removal of parking spaces or if it is located in a Transit-Oriented Development (TOD) area and proposes more parking spaces than the number of vehicle trips generated. The scope of this analysis will be defined during the pre-scoping meeting with City staff, and tailored to the context of each project.
The analysis evaluates the availability of parking in the area surrounding the project site by comparing parking supply to parking demand. The goal is to reach an efficient parking occupancy rate of 85 percent—high enough to minimize excess unused spaces while still ensuring availability. At a minimum, the study must examine on-street parking along the project perimeter and nearby side streets, as well as off-street public parking facilities adjacent to the project.
Parking occupancy is determined using a straightforward calculation:
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Parking supply: Total number of available on- and off-street public parking spaces.
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Parking demand: Total number of those spaces that are occupied.
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Parking occupancy: The percentage of occupied spaces relative to supply.
Additional information required in the parking analysis includes details on existing parking management strategies (such as time limits, pricing, and permit programs) and any street design constraints like curb cuts that could affect parking capacity.
The analysis should focus on peak demand periods, with additional time periods defined during pre-scoping. Parking data must be collected by block face for on-street spaces and by lot for off-street locations. Use of a professional third-party count firm is preferred, though counts by qualified consultants may be accepted if third-party collection is not feasible. High-resolution aerial imagery is not a suitable substitute. The results may be presented in maps or tables, depending on preference and clarity.
In high-demand urban areas, the buffer zone for parking analysis may be extended to account for people’s willingness to walk farther from their parked vehicles. This distance will be determined during scoping.
The parking occupancy rate corresponds to a four-point scoring system used in Honolulu’s Urban Core Parking Master Plan:
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Score 1 (0–50%): Underutilized; excess supply.
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Score 2 (51–70%): Within target range; good availability.
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Score 3 (71–84%): At target; acceptable availability.
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Score 4 (>85%): Above target; constrained parking, mitigation required.
If parking demand exceeds supply, or if project design significantly reduces available parking, the TIA must propose mitigation strategies. These will often include Transportation Demand Management (TDM) and parking management approaches rather than expanding supply. Mitigation may address short-term parking needs through pricing or time restrictions, as well as long-term solutions that support mode shift and reduce drive-alone trips.
Complete Streets Modal Priority Analysis
In alignment with Honolulu’s Complete Streets Ordinance, TIAs must include a Complete Streets Modal Priority analysis. This process evaluates the level and quality of service (LOS) for multiple travel modes—auto, transit, pedestrian, bike, and parking—using a score of 1 (highest performance) to 4 (lowest). The analysis compares these scores against target performance levels based on the street type, as defined in Honolulu’s Complete Streets Design Manual.
Street designations (e.g., Expressway, Boulevard, Main Street, Avenue) determine which modes have priority. For instance, pedestrian and bike modes are typically prioritized on Main Streets, while auto and transit are prioritized on Boulevards and Parkways. A higher-priority mode is assigned a lower target score.
The City’s Multimodal Radar Diagram tool (available via the City’s website) visualizes these scores for each mode and street segment. Each segment is rated for existing conditions and for the proposed project design. The diagram shows how closely the project aligns with modal priorities—closer to the bullseye indicates better alignment.
If a project design fails to meet the modal target for a high-priority mode, the TIA must include improvements or mitigations to address the deficiency. These could include infrastructure changes or TDM measures. If the target cannot be met, the TIA should explain why and describe the benefits of any proposed improvements.
Safety and Access
The TIA must also assess traffic safety. A review of crash data over the past three to five years is required for intersections and roadway segments affected by the project. Data should include all modes—vehicles, bicycles, and pedestrians—and be presented in map format. Crash summaries help identify high-risk areas and inform design changes to improve safety.
Vehicle Miles Traveled (VMT) and Induced Demand
Projects located within TOD or Transit Ready Development (TRD) zones must analyze their VMT per trip in comparison to regional averages. Significance thresholds vary by land use type, and exceedances may require mitigation. Larger projects must use regionally sensitive methodologies, as quick-response tools like VMT+ are not suitable for comprehensive analysis.
Projects proposing roadway expansions or similar improvements must consider induced demand effects. A qualitative assessment should determine whether these improvements conflict with City policies encouraging sustainable transportation.
Neighborhood Traffic and Scenario Analysis
If a project increases traffic on nearby local streets—particularly as cut-through or bypass routes—the TIA must assess whether projected traffic volumes exceed established thresholds. Significant increases may require mitigation or conditions of approval.
Finally, transportation scenarios typically include Existing Conditions, Existing + Project, Future Conditions, and Future + Project, with timelines tailored to project phasing. Additional near-term scenarios may be required for projects with rapid development timelines.
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