Of course once Burnside crossed his bridge his job was not done. It seems one of the bigger complaints against him, in this phase, is that he takes two hours to cross his force. Again I don't think Burnside can take too much grief here. He crossed quite a few men, including artillery and wagons, and that takes time. Also he probably has accepted at least part of what McClellan says about Lee's numbers. So Burnside probably expects that Lee is still in pretty good shape, plenty of men in reserve to deal with Burnside. If this is the situation you know then it makes perfect sense to cross your force, your whole force, and go in as one unit instead of a piecemeal attack. Of course had Burnside made a piecemeal attack it might have succeeded better than he actually did since he might have been able to penetrate closer to town. But then AP Hill might have caught Burnside in the rear and really caused destruction. Hard to say, that's why what-ifs are sometimes pointless.
In any respect the following pictures were taken along Branch Avenue, which is generally the area of Burnside's farthest advance (some units didn't get this far, a few got even closer to town). The first one is looking out towards the area Burnside's men advanced across. The cannon marks a Confederate position. The bridge is generally over the rise on the left side of the picture.
Here's the view on Burnside's left flank. There are two monuments in this picture. The second is left of center on the ridge line.
A few monuments along the road. Just liked the scene. Mike's in the picture which adds or detracts based on your feelings about Mike. (Just kidding, Mike, I still like the shot.)