As it happened, I'd been walking along the Tamar that morning, just upstream - it looked like this. Not my idea of a fun river for a dip.
The New Bridge is a New Bridge in the hobbit sense, for it was built in 1520, which still makes it a considerable update on the closest alternatives. We had to go upriver and back to 1437 to Horsebridge to get across. It turns out, alas, that the Benedictines who built the bridge had failed to properly plan for an increase in vehicle traffic a mere not-quite-six centuries later, and it was a bit busy. So we came back over Greystone Bridge (1439). Clearly someone had done some hard thinking in the two years between the two bridges, and Greystone Bridge is much better structured to take the increased traffic. Well done, monks - well done!