Turkeys can locate the source of calling with pinpoint accuracy. If you have a direct line of sight for 200 yards to a gobbler you call to, he is going to expect to see a hen. When he doesn't he will get suspicious and likely go the other way giving "courtesy gobbles" to join the party. A hen decoy in the roadbed may have helped, maybe not.
Your best bet on a group like that is to get try to gain ground. If you can get even with them and call from off to one side, or circle ahead of the direction they are taking. It's a cliche', but it's tough to pull a turkey to a place he doesn't already want to go. On a group that constantly moves away, hang with them if you have enough property to do so. If you can't get ahead of the flock, stay a couple hundred yards back, out of sight and call softly from time to time like a following hen. Ocassionally you can get a subordinate gobbler to come back and take a look.
"The joy of living is his, who has the heart to demand it." Teddy Roosevelt