Two things: first, FFS use commas and periods.
Second: Wakain, you're saying that fixing bridges with wrenches is unrealistic, but you have no problem fixing burning tanks with 2hp back to full health with the exact same wrench? Then again, you also said that you'd approve the wrench system.
Back to the topic at hand: destroyable bridges would be handy on maps like Falaise Pocket and Bardia (can't come up with other maps with river crossings on bridges) and would be great for bottlenecking advance routes, and if some inconspicous places where you can wade rivers with vehicles would be added, blowing the bridge would not hamper the entire advance, and shouldn't imbalance the maps that much.
Wall of text made short: I approve this idea, but only if alternate routes are provided.