There’s a major Horde living in the nearby train tunnel and they feed at the nearby dry riverbed at night. Try clearing this Checkpoint during the day to avoid alerting the horde especially if you’re not ready to face them yet.
The gas can is located behind the guard booth facing the bridge.
The speakers are located in the following spots:
* Guard booth facing the bridge
* Light pole near the dirt road going downhill
* Light pole near the tent
* Two on the roof of the MMU
The generator is found behind the fenced area. You have to go around to the northwest and pass by the truck to reach that area. Simply juice up the generator and start it up to unlock the MMU and clear this Checkpoint.