The merge point is as soon as the lanes touch. The dominant traffic flow is I5 to I84 and every last one of those cars has to switch lanes to get there, and some traffic will need to cross in front of them to get from I405 to I5. There's about a quarter mile to make it all happen, while on a bridge with narrow lanes 130 feet in the air, moving at speed. No, you will not be leaving large gaps to let people in, LOL. You will back off and leave exactly enough room for a car to get in front of you (assuming you are not just going to trade lanes). It works okay as long as everyone acts as expected and nobody wimps out. It can get dangerous when grandma goes through there and panics when it all gets really dense for a moment.

Which is a great solution if everybody complies, but when you have people unfamiliar with the area, bad drivers, and anxiety over Google Maps directions is when it spells trouble. I've lived in Oregon for over 30 years, so I don't typically have a problem but I get nervous over the unpredictable behavior of other drivers in those situations I outlined.