1.These people mark the trail....
trappers villagers

2.These are used to mark the trail..
airplanes snowmachines dog sleds

3.Part of the trail marking includes. ..
snow plowing building bridges snow forts

4.There are this many crews clearing trail during the race ..
3 2 5

5.One crew does this to the trail in case it snows ..
Plows Stakes breaks

6.The trail is cleared to take away this ..
snow hills dangerous speed bumps icy areas