I think the best place to build the new I-5 Bridge over the Columbia River is on the east (upriver) side of the existing spans. Looking at a map, I-5 veers to the east, especially on the north (Vancouver) side. That way the bridge could be shorter, have a smaller footprint, cost less, and displace fewer businesses, etc.
In order to be high enough for the river traffic, it would be too steep for light rail. I am not in favor of light rail, but if we must have it, put it on the newer (southbound) span of the existing bridge.
I think a better idea than light rail is express buses that can drive on a steeper bridge. The south (Oregon) side of the bridge should have freeway-type onramps and offramps to eastbound and westbound Marine Drive, 99E, and 99W to avoid congestion and keep traffic moving. Build the first of two bridges east of the freeway, temporarily having three lanes in each direction. Then tear out the present northbound bridge and build the second bridge in its place.
Another alternative would be to leave both existing bridges in place and use one for light rail and the other to only access Hayden Island.
