A tunnel cannot be feasibly built within the footprint of I-5 without eliminating important connections to Hayden Island, downtown Vancouver and SR-14. It also comes with significantly more operational, environmental and historical resource impacts, and would cost more than a replacement bridge.

For more information about the suitability of an immersed tube tunnel, view the Tunnel Concept Assessment Opens in new window.

The recommended Modified LPA aims to improve freight mobility through interchange design improvements, integration of ramp-to-ramp connections (auxiliary lanes), extension of light rail across the river, and improved bicycle and pedestrian facilities. Interchange improvements and auxiliary lanes can help freight move through the corridor safely and more efficiently compared to current conditions. Extending light rail across the river and improving active transportation options will promote mode shift for travelers currently using single-occupancy vehicles. With fewer cars on the road, additional space to merge safely, and thoughtful design considerations, freight can experience improved travel times and reliability. The proposed improvements will be thoroughly analyzed through the upcoming environmental review process to ensure they meet freight mobility objectives.

While the previous planning effort identified a grade of just under 4% for a 116-foot clearance bridge design, the IBR Program has not reached that level of design and final road grades have not been confirmed. It is not unusual to have highway grades at 4% or steeper. In both Oregon and Washington there are stretches of interstate highway that feature grades steeper than 5%.

As designs progress, the program will ensure that any design accounts for the safety of all modes of travel and will meet or exceed all local, federal, and state safety and design standards.

There is not one giant pot of money for the IBR Program that can be used for other purposes like retrofitting bridges around the NW Oregon and SW Washington region. Funding for construction will come from a variety of sources, including state and federal transportation funding and tolling. All of these funding sources, whether they are dedicated by the state legislatures or competitive grants, must be approved specifically for the IBR Program and must be used to address the identified transportation problems.

Even if it were possible to divert funding allocated to the IBR Program, the need for a local and regional transportation system lifeline able to withstand a significant earthquake would remain. By replacing the Interstate Bridge with a new seismically resilient, multimodal solution, the IBR program would contribute to seismically updating the regional corridor along with improving transit options and reducing safety and congestion issues on Interstate 5.