You should put some some levels into the map. As of now, it's a flat indoor way conecting two rocky rooms.
One possibility is, you could make the middle way going high and the two side ways oing low, for instance (like in shazam22).
Also keep in mind that going through the middle way will take LESS time than going through the two side ways, so you might add a few obstacles so that the mid won't be the only way used in your map.