Goodman Games

On map two there are those lightning bolt symbols with 1000, 1500, 2000, and 2500 feet. What do they stand for?

Thanks in advance.

Those are drafting symbols. They represent gaps in the map. For example, the first one you mention with 1000 represents a 1000 foot gap in the map from one end of the "lightning bolt" to the other end. It shows that the tunnel continues for a long distance with out actually drawing it.