When Fishing roadbeds in the winter with a crankbait you’re looking for a reaction bite.   A jig or Carolina Rigged plastic represents something to eat. Bass aren't hungry often enough in winter to take those lures.   Depending on the depth, you will need a crankbait capable of diving a minimum of 20 to 25 feet to reach your intended target in the timeliest manner.   The best places to look for roadbeds are along the edges of channels.   Cast parallel to the road, starting with the edges first.
Roadbeds are depicted on many maps, but they can be found with a good depth finder.   Look for any depth changes, no matter how slight that might be. Something to keep in mind is that ditches usually border a roadbed and they too can hold fish.
Roadbeds are capable of holding big schools of fish, but expect them to be concentrated in a small place.   When you do find them you’ll see that most of the time there will be some type of change in the roadbed.