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

A 2013 ODOT study found that auxiliary lanes are an effective way to improve safety and reduce bottleneck congestion. A ramp-to-ramp or auxiliary lane typically provides a direct connection from one interchange ramp to the next. People can transition from one ramp to the next without having to merge into through traffic. This improves overall safety and operations of the highway.

Three Interstates (I-5, I-84, and I-405) intersect in the short distance between the Morrison Bridge and the Fremont Bridge, creating the biggest bottleneck in the state of Oregon. This outdated design with closely spaced interchanges and without shoulders has resulted in this section of I-5 having crash rates that exceed the state-wide average for comparable facilities.

With a new ramp-to-ramp lane in each direction on I-5 from I-84 to I-405, drivers will experience a safer, more reliable trip with less potential for crashes. The lanes would allow drivers more space to merge and eliminate the need to do so with through traffic when approaching the next exit. Drivers will be able to remain in the right lane and exit at the next opportunity. With extra space to address crashes, breakdowns, or emergencies, drivers will be able to avoid the disruption of closed lanes or stalled vehicles in the middle of the road.

Adding these upgrades is expected to:

  • reduce crashes up to 50 percent on I-5;
  • save over 2.5 million hours of travel time each year;
  • and result in $732 million in economic benefits while staying within ODOT’s existing property.

The addition of continuous 12-foot shoulders for the length of project area will also create space for disabled vehicles to move out of through traffic, allow emergency vehicles and buses to travel more quickly, and keep people moving.

*The images on this website are conceptual drafts and are subject to change based on technical analysis and public input.

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