Thank you for helping them across, it's great that people do this.
Of course, always be careful when crossing the road yourself. If the road is too busy, such as a highway, you can get in trouble for pulling over and getting out.
Also, to any Texas readers, unless the recent law was retracted somehow (I don't believe it was, sneaky politicians) it is illegal to do this. You cannot stop and touch any reptile or amphibian wildlife on state land (road, sides of roads), it is now considered hunting. So be aware of your state laws, or don't get caught.
The reason more turtles are out on road ways is obviously because of human encroachment on what territories they do have. They also move over large areas to look for water, food, and good nesting sites. Males are also on the hunt for females.
Where I live is just outside of town, semi rural, so there's at least 3-4 wild box turtles that live in the area, that I know of. They like to raid our tomato patches.