I always thought bike highways should be available for cross town trips... the idea would be something that would permit a cyclist to get up to speed and then not have to worry about intersections or traffic lights. Such a highway would use exit ramps and on ramps (not really that big of a thing for a good bike path). Such a highway would go under or over surface streets used for pedestrians or automobiles. Of course the highway would have to serve the same areas as an automotive freeway... for cyclists are people and want to access the same resources as other people.

I saw a pretty good example of something close to this in Oulu Finland... no it wasn't perfect, but it was vastly better than any thing I had experienced in the US.

In San Diego there was a new bike path installed by Caltrans years ago... it was designed for cyclists after the state highway road was turned into a limited access freeway. I am talking about the route 56 bike path. And on certain parts of that bike path, there are designs similar to the Oulu paths... and they work well.

This first photo shows a ramp for leaving the bike path and going to the surface street.


This shows how the path goes under the surface streets and is laid out right next to the freeway.


Of course the biggest disadvantage of being right next to the freeway is the noise. But in this layout, you also access the same exits that the freeway offers.

Between Davis and Sacramento is a long intracity bike highway. Somewhat similar to the idea discussed in the OP. Seems like a good idea for tying together close cities and bedroom communities.

Hey all it takes is the same commitment that went into the construction of the Interstate Freeway system in 1956.