Pump Jack is the least popular map on Combat Arms, due to the sniping outpost upstairs according to Pump Jack haters, but a great map for playing Capture the Flag nonetheless. It features a large building with two spawn points at each end, with a large above ground territory and a sniping post in between.
There are several trains around the area, and a special "secret area" on top of some of the trains. The upstairs is often used for sniping, and is usually tried for being "taken over" by one of the teams. The team successful in doing so usually wins the game, and by a long shot at that. The map is known for its boxes and trains scattered around the levels with fences changing your path.