Consider this bike route, as suggested by Google Maps
I have asked Google Maps to calculate a bike route from San Tomas Expressway to Winchester Boulevard in Campbell. I noticed that Google Maps goes out of its way to avoid the direct off ramp from San Tomas to Winchester
Instead, it tries to draw the route through various side streets. (If you try switching between the "car" and "bicycle" routing modes you'll immediately see what I mean). Trying to force it to use the ramp (by adding intermediate waypoints) results in nothing. It just won't use the ramp. What could be the possible reason for that?
I know that ramp pretty well. One thing that comes to mind is that Google might consider this ramp to be unsafe for bicycles: it is relatively narrow, has no perceptible bike lane and is mostly unlit at night.
Another theory is that ramps like this might be closed for bicycle traffic in California (according to the vehicle code). Does anyone know this part of the law? I understand that freeway ramps are certainly off-limits for bicycles. But this happens to be an expressway ramp, where both the expressway itself (San Tomas) and the other street (Winchester) have well-established bike lanes.