Great map, really enjoyed this. Given, it's a beta, so things like textures and what not aren't complete.
Couple things.
-People can get behind the fence on the side road of the bridge, on the backside of the terrain geometry. Makes it tough for the specimen to reach them.
-The side paths can reduce the swarm down to two angles. On hard, it was still pretty challenging. But that proved to be the easiest spot to defend, and we went back to there quite a bit. Maybe add a spawn from above, or allow the specimen to come out of the water.
Super work.