About
Project elements
When funded, this project will create a dual lane exit from U.S. 26 eastbound to I-405 southbound by converting the middle lane to Market Street to an option lane to either Market Street or I-405 south. This would mean two lanes through the ramp tunnel from U.S. 26 east to I-405 south.
This will require closing the low-volume Montgomery Street on-ramp to I-405 south to improve sight distance and safe merging distance.
Background
- This improvement was identified in ODOT’s 2019 Congestion Bottleneck Operations Study, which sought to identify freeway improvements of a relatively modest scale to reduce congestion, reduce crashes and improve travel time reliability.
- The Westside Multimodal Improvements Study (WMIS) led by ODOT and Metro in 2023-24 recommended this improvement as a Strategic Capital Investment. The WMIS effort included extensive outreach, and the findings and next steps were endorsed by Portland City Council.
- The Metro Regional Transportation Plan identified this segment of the freeway system as not meeting the region’s throughway reliability policy. Metro’s travel demand model forecasts the length and duration of delay to continue to grow, even with development of all transportation projects planned between now and 2045.
Why this is needed
Analysis
We have completed planning level traffic operations analysis, predictive safety analysis and origin-destination analysis to determine benefits and impacts of the project. Key findings from this work include:
- Up to 23% reduction in fatal crashes and up to 31% reduction in serious injury crashes.
- Balanced use of the center and right lanes from the Vista Ridge Tunnel to the I-405 SB ramp would reduce speed differential during peak traffic and lower the likelihood and severity of crashes.
- Closing the Montgomery Street on-ramp is expected to result in local traffic instead using the Broadway Street on-ramp to I-405 south.
- The Montgomery Street on-ramp has relatively low usage, with an average of 6,700 daily trips compared to 28,500 entering I-405 SB from US 26.
- Improved throughput from U.S. 26 east to I-405 south would draw regional trips that are using local roads back to the highways, with less peak hour volume most notably on SW Market Street and SW Columbia Street.
Location
U.S. 26
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The U.S. 26 eastbound interchange with I-405 southbound from just east of the Vista Ridge Tunnel to the Broadway St off-ramp from I-405 south.
Cost and Funding
TBD
Benefits
- Up to 15% reduction in total number of crashes per year in the project area.
- Up to 1,200 more vehicles per hour from U.S. 26 eastbound through the tunnel to I-405 southbound.
- Faster peak travel time on U.S. 26 eastbound, saving up to 5 minutes (~12%) for longer trips.
- Reduced diversion to local streets as more trips stay on U.S. 26, I-405 and I-5.
- Improved utilization of existing U.S. 26 eastbound lanes and reduced conflict points on I-405 southbound.
- Implements improvements consistent with the Westside Multimodal Improvements Study.
Additional Information
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