15 miles for a 1 mile ride? Maybe I am missing something but you do realize it is perfectly legal to ride on non access controlled roads. In fact it is illegal in most placed for adults to ride on "side walks".

Find us a map of the close bridges you are concerned with crossing that have hwy access ramps. Google will give you a ling in the upper right corner of the map. Let us take a look at them to see if they look unusually dangerous for some reason.