I-5 Ramp-to-Ramp (Auxiliary) Lanes & Shoulders

The short section of I-5 between the I-84 Interchange and the I-405 Interchange has several closely spaced on- and off-ramps. This segment of I-5 also experiences some of the highest traffic volumes in the state. With heavy traffic, merging and weaving to get on and off the highway is a challenge. As a result, it has the highest crash rate in the state. All of the activity and movements between these two major interchanges creates a bottleneck on this section of I-5, causing safety issues, congestion and traffic delay.

To reduce crashes and improve the flow of traffic, ODOT will add ramp-to-ramp lanes (also called ‘auxiliary lanes’) between the on- and off-ramps from I-84 to I-405. These lanes allow vehicles to enter and exit the highway more smoothly. This project will also add shoulders to the highway so stalled vehicles can move out of traffic and emergency vehicles can quickly respond.

What is a Ramp-to-Ramp Lane or ‘Auxiliary Lane’?

Ramp-to-ramp lanes, also known as auxiliary lanes, are an effective and cost efficient way to improve safety and reduce bottleneck congestion. A ramp-to-ramp lane typically provides a direct connection from one interchange ramp to the next. The lane separates the slower vehicles entering or exiting the highway from the higher speed vehicles continuing to drive along the highway. This improves overall safety and operations of the highway.

Learn More About Ramp-to-Ramp Safety Improvements

In 2009, ODOT began a new approach to deal with major recurring bottlenecks on local highways and develop cost-effective improvements to address safety and congestion at certain locations. Forty percent of all congestion is predictable, caused by bottlenecks or physical constraints of the roadway. Many bottleneck locations are also high-crash sites. Crash incidents increase congestion levels, causing more delay and longer recovery time for the highway. The Corridor Bottleneck Operations Study (CBOS) identified areas of recurring congestion along five key Portland metro area corridors (I-5, I-205, I-84, I-405 and US 26). The study recommended low-cost, highly effective solutions to improve safety and reduce congestion at these locations. In many cases, ramp-to-ramp (auxiliary) lanes were the recommended solution.

(Source: FHWA Traffic Congestion and Fatality Report: www.tinyurl.com/fhwacongestionreport)

Locations Where ODOT Implemented Ramp-to-Ramp Improvements

I-84 Eastbound Ramp to I-205 Northbound: ODOT extended the existing ramp-to-ramp lane on I-84 at the Halsey Street ramp to the I-205 northbound ramp. The new ramp-to-ramp lane reduced crashes by 14% and reduced daily vehicle hour delay by 10%.

I-5 Northbound Ramp to I-205: ODOT constructed a ramp-to-ramp lane on I-5 from Elligsen Road to the I-205 off-ramp. Drivers traveled through the corridor 10% faster during the evening peak period and afternoon commute times became 20% more consistent.