Metro 2033

On the "Trolley Combat" level, you will come across a tank and drive past it, you will encounter another tank later on which you can destroy, it will be driving on a bridge parallel to your own. When your driver shouts, "Shoot the supports they look weak!" that's your cue to, well, shoot the support beams under the bridge the tank is on, Shoot them enough and the bridge will collapse and take the tank with it.

This is an easy (story?) achievement,
in this level you're in a turret-trolley almost all the time. Kill everyone on
your way after the 'excuse' of your buddy against the Nazi fails.
A little tip on the enemy-trolleys: Shoot the gunner first (Between the armor
plates), and then the driver.
After fighting trough a couple of battles you will face a point where you get
stuck with your trolley. The enemy panzer/tank will push the train off the
tracks (the one one the other side), from this moment on you'll continue to
drive on. Immediately start shooting the support-pillars at the other side (the
ones the panzer is driving over).

If you succeed then the panzer will fall down and your achievement pops.