The bomb train is a device in Jak 3. It is an explosive-laden carriage encountered in the eco mine. Its original purpose remains unknown, although Jak found four of these in the mission "Explore eco mine". Three of them were in the area where the Precursor robot was fought, and the fourth was activated by Jak to blast open the door that leads to the area itself.
When Jak threw a nearby lever, a large, mechanical arm carried it to an elevator platform where it moved to the main area together with Jak. The bomb train then moved forward on the rails on its own. This forces Jak to escort the bomb train by hitting targets on the track causing pieces of the railway to fall in place properly. At the end it drives into a locked door allowing Jak to continue.
The last three trains were encountered at the same time as Veger's Precursor robot, each stuck on a broken railway above the robot. The robot used an attack that caused multiple pillars to rise from the area, allowing Jak to reach the necessary height to shoot down the trains. Shooting them causes the carts to get loose and fall down onto the boss, causing it to be damaged.