QUOTE (toturi @ Apr 25 2009, 08:56 PM)

Ramp shaped barrier. Lift and topple. No need to beat OR.
this. MBTs, (modern ones, anyway) are designed against extremely specific threats, namely other MBTs or vehicles trying to shoot holes in them with armor-piercing rounds, from a frontal aspect. this means they are extremely vulnerable to rear shots or track damage.
for example:
During an early attack on Baghdad, one M1A1 was disabled by a recoilless rifle round that had penetrated the rear engine housing, and punctured a hole in the right rear fuel cell, causing fuel to leak onto the hot turbine engine. After repeated attempts to extinguish the fire, the decision was made to destroy or remove any sensitive equipment.also:
During the major combat operations in Iraq, Abrams crew members were lost when one tank of the US Army's 3rd Infantry Division, and US Marine Corps troops, drove onto a bridge. The bridge collapsed, dropping the tank into the Euphrates River, where four Marines drowned.More here, including several M1A2s disabled by RPG7s, which is a weapon that predates the Abrams by 20 years. in the technological race, Armor never wins.