Help! I found the first key to get the poison gas in the wrecked jeep under the bridge but can't find the second one. I'm about ready to give up on it so can use some help. Thanks!
The second key is in a jeep on the north side of the bridge. To get to it you need to walk along the bridge until the anomalies block your path, then there will be a ladder to your right. Climb up that and walk along the pipe until you come to a jeep with a stashbox in the back. Drop down and loot the box for the key and some documents.
Just to add to what Jarvis said, yep thats where they are. If you see it as there being two jeeps with the keys - one at the most northerly end, and one at the southerly end thats fallen down with the collapsed part of the bridge, then you should find them :)
As Jarvis says, you can use the ladders and things to skirt around the anomalies - there are lots of gravity ones that whilst they dont totally suck you in like some in the game, do nick away at your health.
Another thing to be aware of - make sure you have about 10 -12kg of free carrying capacity, or have a hercules med. The poison gas canister weighs a lot, and you will also find a few stashes around there. Make sure you can carry all your lovely loot :)
Oh and be sure to sheck the scar anomaly for an artifact. I would say that as I love artifacts lol
Also, and this is how I found it, read the memo where you found the first key. It will say who has each key, and you can extrapolate from the convoy list where to find the other key and the Gas canister. I stumbled on Key B, and finally figured out what was going on when I read the note.