While you are Arc welding you have to be in the right position allowed by the welding rod also you have to keep the speed just right or else the weld will not hold. When you are doing heavy Construction like on a bridge you can’t afford to mess up. Friday night at 8p.m. the Bay Bridge will be closed for seismic retrofit and will be reopended tuesday morning at 5a.m. Contractors are reinforcing the bridge in sections and will be working on the eastern span about 1.2 miles long. Mainly they will be welding supports and indavidual columns. These new supports will help prevent the bridge from failing in any earthquacke senario like the 1989 Loma Prieta Earthquake. Engineers used “Rock Motion” to calculate what the bridge will do in the case of an earthquake and designed support columns to prevent the twisting of the metal. If you plan on visting San Fransisco this weekend you should take B.A.R.T or you will have to take the round about way of either the Richmond bridge or the San Mateo bridge. If you choose to drive the bridge will be open going eastbound only. Information here was provided by the following sites:
mcab88 