In order to retain pedestrian connectivity while Somerset was completely dug up, a temporary boardwalk was installed off the side of the viaduct.
The bridge's railings were temporarily removed to provide access. You can see the oval-shaped railings sitting on the sidewalk here, with some connecting pieces standing on their ends in a couple of piles:
While the boardwalk was being prepared, and before the hole was excavated, pedestrians crossing the bridge were directed by two rows of fencing to the middle of the roadway, which was closed to cars.