How does a track physically get a dead or live rail? We hear about this all the time, but what physically makes this happen? Does the track maintenance person create the bias on the track? If so, is it intentional?

Thanks

Also, and I hate to mix questions because you'll end up not getting an answer to one or the other, but . . . do the TG numbers adjust for track biases. That is, would you adjust just some horses in a race with a rail bias or is it an all or nothing adjustment. Meaning, you adjust all the horses for a fast running track one day, or none of the horses?