Many factors can contribute to increased traffic, including a community’s increasing population or economic growth. Auxiliary lanes are intended to help existing traffic move more smoothly. Nearly 99% of vehicles that get on I-5 at the Fremont Bridge (I-405) and head south exit within about two miles at either Broadway, I-84, or the Morrison Bridge – all exits within the project area. With the auxiliary lane, the vehicles traveling from I-405 to the exits within the project area will not have to merge in and out of traffic.
In the Portland Metro area, ODOT has completed or is planning auxiliary lane projects on I-5 and I-205. For example, the new auxiliary lane on I-5 southbound from OR 217 to I-205 addressed the bottleneck on that section of highway and improved upstream traffic as well as traffic on OR 217. The improvements reduced congestion from five hours a day to one hour a day on that section and saves motorists an estimated $8.4 million of delay each year.