Gears of War Act 3 - Coalition Cargo
On the right side of room is the cart control Marcus is looking for. Walk up to the computer and use it.
This will open two huge doors. Go through the door to the left and down the stairs. The squad will jump in the carts.
There is not much you can do here. Just ride the cart and shoot the locust that come from the sides.
At the end of the cart trip there will be a door with a button next to it. Push the button to open the door.
Go through the door and the door to the right. In this room turn left and walk to the door. Push the button next to it.
When Marcus pushes the button, a wretch will attack. Kill the wretch.
After the fight press the button again. The door will open and there will be four wretches in the hallway. Walk to the end of the hallway and press button next to door.
On the other side of the door is a second door. Press this door's button as well.
Follow the hallway after the second door. About half way down the hallway will have a downward slope. At the end of the hallway two wretches will attack.
When Marcus enters the room at the end of the hallway, he calls control and she says that she's raising the platform. Well here is a surprise there's a Boomer on each of the platforms. Take the Boomers out.