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The City of Portland, Oregon

Planning and Sustainability

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Phone: 503-823-7700

Curbside Hotline: 503-823-7202

1900 SW 4th Ave, Suite 7100, Portland, OR 97201

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Video Simulation of the Auxiliary Lanes and SB Braided Ramps

The southbound weaving section on I-5 to I-84 is one of the worst in the region, which is reflected in it being among the top crash locations in the state. A video has been created to display the potential improvements under consideration for I-5 and the Broadway/Weidler freeway interchange. The traffic represented in the simulation is existing volumes during the shoulder peak period of 2-3pm. The video clips show the following elements:

Existing Video Recorded Conditions vs. Existing Traffic Simulation

This shows how the simulation model closely represents real conditions. Note the challenges of vehicles trying to change lanes within the short weave section.

Existing Traffic vs. Auxiliary Lane Alternative

For I-5 southbound, weaving is still an issue but traffic flows are better for the inside and center lanes due to the addition of the auxiliary lane. The I-84 back-ups would occur in the auxiliary lane, out of the I-5 through traffic.

Existing Traffic vs. Aux Lane & SB Braided Ramp Alternative

For I-5 southbound, mainline traffic flows well with the weaving conflict removed. The I-84 back-up is now on the braided ramp section rather than the mainline.

This analysis shows that the Auxiliary Lane alternative would reduce congestion in the I-5 Rose Quarter area and improve traffic operations for I-5 through movements. The improved traffic operations are also anticipated to be reflected in safety improvement. The Auxiliary Lane and Braided Ramp alternative would have an added benefit to the auxiliary lane improvement alone by removing the weaving conflict completely, thereby improving safety.