Freeway on and off ramps present their own particular issues... several of the ramps I routinely cross are of the sweeping type John E mentions... and sadly this is the only through surface road in this area of a multitude of freeways... and even the surface road has a speed of 45MPH, which is often pushed to over 50MPH by motorists... especially those that wish to enter the freeways.
In the first pic, there are three ramps for the same freeway... all shown centered in the pic. The first two are on ramps, and the last big loop is an off ramp where motorists cannot even see back up on to the surface street until they have nearly entered it.
While these are all within about 500 feet of each other I have to ride very cautiously through the area in slightly different ways: The first ramp I simply look back, and then take the right most through lane and hold it past the ramp, while still in that right most lane, I look and study carefully for any movement from vehicles preparing to turn left toward me across my "bow" to also enter the freeway. Fortunately this is a downhill ride, so I focus on my speed and position, and not my pedaling.
The third ramp is an off ramp, and I yield to motorists... as I know they do not see any approaching traffic until it is too late. I then become invisible as we all go under a bridge... at that point I am as far to the right, in the bike lane as possible.
I put a yellow line on the pic to show about where I travel... but it is not that accurate.
The second pic is a freeway offramp that I typically travel... this is the only connection to a valley where I work and bicycles are permitted on the freeway at this location. The fear factor comes in as I leave the freeway and have to cross the right turn off ramp near the top to make my left turn. This is all shown in yellow. The crossing area I emphasized in red. BTW I am doing about 10MPH here as this is an uphill grade. The only way I am convinced that this can be done safely is for me to signal for a long time and get the attention of at least one vehicle using that exit. When I have their attention, and know that they have seen me by slowing way down, I use that car as a shield to cross the ramp to make the left turn.