Switchback

Zack and Axle find a road going down a steep hill. But Axle doesn't like the road too much because it goes back and forth across the hill instead of straight down - which is much faster. They call Sandy the Bulldozer to change the road to one that goes straight down. But when Sandy is finished they find that getting up the road is too steep. They realize going across the hill makes it easier to climb, but they have to change directions several times before they get all the way to the top. In the end, they have built a switchback road to the top of the hill, the same kind of road they had before. But Axle doesn't mind, now that he knows why the road looks like that.