I think you will find it is temporary, they are restoring the steel work & concrete pillars of the bridge. Pass over the bridge every day & it looks like they have vibrated sheet pilings to create a dry area from tidal flow while they work on the concrete pillars. The notification we got in the mail from the council said that it would be completed, I think from memory, by the end of April. Once restoration is completed they will probably remove pilings & excavate the filled in area. They have done a fair bit of sand blasting on the underside of the bridge to recoat the steel work,