Multimodal Transportation Impact Analysis
After presenting the project background, description, and study area, the TIA must analyze the project's potential effects on the surrounding transportation system. This section should include a clear explanation of the analytical years, existing transportation conditions, estimated project-generated trips, and future conditions with and without the project. The analysis must also identify any significant transportation impacts. The following subsections outline the necessary components of the multimodal transportation impact analysis:
A. Existing Traffic Conditions
Begin by stating the assumptions used in analyzing current traffic conditions. Describe operational performance for each transportation mode (auto, transit, pedestrian, bicycle), consistent with agreements made during the pre-submittal/scoping meeting.
B. Forecast Future Traffic Conditions
Define the future analysis year, typically within 10 years of the anticipated project opening. Use OahuMPO model forecasts and Hawaii Department of Transportation (HDOT) data trends to project background traffic conditions. Avoid using a generic growth rate. List and describe relevant background developments expected to be operational by the analysis year and include their trip impacts.
C. Project-Specific Traffic Conditions
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Vehicle Trips: Use the Institute of Transportation Engineers (ITE) Trip Generation Manual to estimate peak-hour or daily vehicle trips. The regression method or average trip rate should be selected based on available data and confirmed during scoping. If the proposed parking supply exceeds trip estimates, parking stall count may serve as the trip proxy.
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Person Trips: Estimate person trips across all modes, incorporating pedestrian crossing analysis (NCHRP 562), mode shares from the American Community Survey, and future projections based on parking supply, walkability, transit access, and scheduled transit service. Provide multimodal trip estimates.
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Trip Assignment and Distribution: Show maps indicating inbound and outbound trip percentages for each mode at key locations. Base distribution assumptions on traffic counts and OahuMPO model outputs.
D. Level and Quality of Service by Mode
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Auto: Report peak hour levels of service (LOS) and volume-to-capacity (V/C) ratios at study intersections and corridors. Include collected turning movement counts, geometry, traffic control, and simulate traffic where needed for corridor-wide assessment.
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Pedestrian: Use the Pedestrian Environmental Quality Index (PEQI) methodology to assess the pedestrian network’s existing and future conditions. Report PEQI scores before and after development.
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Bicycle: Evaluate Level of Traffic Stress (LTS) for existing and proposed bicycle conditions. Describe the characteristics affecting LTS and any network changes due to the project.
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Transit: Assess the availability, accessibility, and quality of transit service. Compare Transit LOS before and after the project using established performance measures.
E. Complete Streets Modal Priority Analysis
Using multimodal radar diagrams, compare background and project conditions to determine modal performance relative to Complete Streets goals. Identify where modal targets are not met and recommend improvements for each transportation mode.
F. Safety Analysis
Present crash data from the past 3–5 years, summarizing frequency, severity, and location. Include fatal and non-motorized user collisions. Map crash data to visualize patterns. If the project alters geometry or control at intersections, apply appropriate crash modification factors based on the Highway Safety Manual to predict future crash outcomes. Summarize safety benefits or concerns in a table.
G. Other Evaluations
Include additional assessments as needed, such as parking supply and demand, vehicle miles traveled (VMT), neighborhood traffic analysis, and induced demand.
Project Mitigation
Detail the transportation demand management (TDM) strategies and infrastructure improvements proposed to mitigate the project’s impacts. These strategies should align with the City’s Complete Streets objectives and be categorized as Required, Better, or Best.
Conclusions and Recommendations
Provide a concise summary of key findings and mitigation measures. Highlight multimodal traffic conditions before and after mitigation, and outline commitments to TDM and infrastructure improvements. Categorize each strategy by effectiveness and relevance to the project’s impact
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