Bridging is a specialized topic, though, and the Antietam is such that musket fire can reach across the entire creek (50-100 feet width) but it's also way too wide for a few planks to get across it. This means it takes long enough for the enemy to react, and attempting to build a bridge within range of the enemy can take days even if done by specialist troops and only harrassed by a few sharpshooters (cf. Fredericksburg).I think my point was missed. The troops were not given orders to bridge the creek. If two brigades assault the stone bridge while two other brigades throw timbers over the creek at two different points, the Confederates could not defend.. One or two crossings might be stopped, but not all three.
With hindsight it might have gained the bridge earlier, but what it actually took to capture the bridge was pretty simple: put artillery on the high ground to drive off the Confederate batteries covering the bridge.