I pretty sure this concept will be shelved for quite some time. It was only done to appease the industrial property owners in the area and assure them that there was an option to underground the freeway without impacting private property. The cost of $11,000 means that virtually no serious engineering work went into the study.
The City and ODOT should just dump this freeway section, add a lane to I-405 and re-designate it as I-5, and institute congestion pricing on it through downtown. May cap a few blocks of the I-405 could be part of it.. who knows.
