City and County of Honolulu: Transportation Impact Analysis (TIA) Study Process
Chapter 2: Study Process
This chapter outlines the step-by-step process for preparing and reviewing a Transportation Impact Analysis (TIA) for the City and County of Honolulu. The TIA process is intended to align proposed development projects with Honolulu’s goals for a sustainable, efficient, and multimodal transportation network.
2.1 Consistency with Plans and Policies
All TIA studies must be consistent with the City and County of Honolulu’s adopted plans and policies. The overarching vision, including the Complete Streets Policy outlined in Revised Ordinances of Honolulu (ROH) Chapter 14, Article 33, emphasizes creating streets that are safe and accessible for all users. This includes pedestrians, bicyclists, motorists, public transit riders, people with disabilities, seniors, children, and commercial goods movers.
In accordance with this vision, proposed development projects should identify and implement mitigations that support multimodal access and safety. Projects must reference key planning documents, including:
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Oahu General Plan
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Regional Development and Sustainable Communities Plans
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Complete Streets Checklist and Design Manual
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Honolulu Transit-Oriented Development (TOD) Plans
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Special District Design Guidelines
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Oahu Regional Transportation Plan 2045
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Statewide Pedestrian Master Plan
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2019 Oahu Bike Plan Update
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Oahu Pedestrian Plan
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Subdivision Rules and Regulations
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Bus-Rail Integration Plans
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Honolulu Urban Core Parking Master Plan
Each of these plans contains guidance to ensure development projects support the City’s long-term transportation and land use goals.
2.2 Data Sources
Accurate and reliable data is critical to the TIA process. Data sources should be consulted early and reviewed with City staff. Primary data sources include:
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OahuMPO:
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Travel Demand Forecast Model (TDFM)
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Sugar Access Model (for pedestrian and bicycle accessibility modeling)
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Hawaii Department of Transportation (HDOT):
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Annual average daily traffic counts
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Current and future highway project database
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Crash data (via ArcGIS)
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Hawaii Department of Health (HDOH):
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Crash and injury data through its Injury Prevention and Control Section
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City and County of Honolulu:
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Transit ridership data for TheBus (requestable via DTS-TMD Form)
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Pedestrian High Injury Network maps
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UrbanLogiq data on travel times, safety analytics, pedestrian mobility, and origin-destination patterns
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The data inventory should be reviewed in the pre-scoping meeting to identify what is readily available and what needs to be collected.
2.3 Scoping the TIA
Engaging City staff early is essential to defining the appropriate scope of a TIA. Scoping ensures that the study reflects the potential multimodal transportation impacts of a proposed project and identifies mitigations that are feasible and consistent with City policies.
2.3.1 Pre-Scoping Meeting
A pre-scoping meeting is required and should include the project sponsor, transportation consultant, and relevant City staff from the Department of Transportation Services, including the Transportation Planning Division (DTS-TPD) and Traffic Engineering Division (DTS-TED). A peer review consultant may also be included, depending on the project.
At the meeting, the team will:
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Review the proposed project and estimate potential impacts
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Define the scope of the TIA
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Identify required analyses and assumptions
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Discuss mitigation measures
The study area, analysis methods, and data collection needs will also be determined.
2.3.2 Preparing the Scoping Memorandum
Following the pre-scoping meeting, the transportation consultant will draft a Scoping Memorandum that includes:
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Project description (including development type and size)
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Proposed land uses
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Modeling tools to be used (e.g., OahuMPO TDFM)
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Study intersections and roadways
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Trip generation and distribution assumptions
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Proposed data collection (e.g., peak period counts)
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Mode split assumptions (for auto, bike, pedestrian, and transit)
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Evaluation methods and analysis scenarios
Maps showing project location, nearby developments, and study facilities should be included. The memorandum may also include a plan for proposing mitigation measures.
2.3.3 Review of Scoping Memorandum
City staff will review the draft Scoping Memorandum within 10 business days and may request revisions. Once approved, the memorandum forms the basis for the TIA.
Revisions to the scope may be necessary later in the process, and would follow the same review steps.
2.4 Reviewing and Finalizing the TIA
Using the approved scope, the transportation consultant will conduct the required analysis. The draft TIA will be submitted for peer review (at the sponsor’s expense) or directly to City staff if peer review is not required.
Peer review comments will be consolidated and sent to City staff for final approval before being returned to the consultant. If major comments arise, a follow-up meeting may be held.
The consultant must respond in writing to all review comments, including a redlined version of the revised TIA. This cycle may repeat until all concerns are addressed. For budgeting and scheduling, assume up to three rounds of revisions to the administrative draft.
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