 In order to change the pile caps on the Whiteson Bridge, the Salem 22 Bridge Crew has several goals, to work efficiently, safely, and not impede the flow of traffic over the bridge. To do this, they will be setting staging under the bridge, to jack and hold the bridge deck up while they remove and replace the pile caps. This will be done while traffic continues to use the bridge, with most motorists unaware of what is happening below them. The first stages of a pile cap change involve setting and hanging the needle beam staging. The needle beams must be level and secure, as it will provide the work platform for the crew. The beams are hung by chains from the structure itself, and will be set at a height of approximately eight feet on this work zone. Deck planks are used initially to cover the beams, and then they, in turn, are covered with plywood to create a smooth, stable work area for the crew. While the crew works below on the base they have built, the crane is left parked above the staging. Traffic is diverted to one lane, and flagger control is responsible for safely managing the work zone for the traveling public. Standard signing, coning, and flagging procedures are necessary while the crane is on the bridge. The crane van explains another safety procedure for those working below. I'd like to show you what we use as standard body harness, and if you'll turn around Phil, we have a lanyard here with a dyna brake system. This is a standard five-foot lanyard with a dyna brake. There's approximately six foot of rip cord in there, and I'd touch on that we're not using these on our particularly staging today because of the height. We're only about eight feet off the ground, and our safety manual says anything over ten feet we would be required to use the body harness and safety lines. After the staging is built and ready, shims are placed around the individual piles in preparation for placing clamps around the piles, which will eventually hold the jacks used to lift the bridge deck. A piling gauge is used to determine the sizing of the piling and the amount of shims needed to hold the sixteen and a half inch pile clamps in place. This is determined by simply placing the gauge around each pile and seeing how many shims are required to make the clamp snug against the pile. After shimming the piles, the next phase in the cap change is putting the pile clamps in place. The matching circular clamps are moved into place across the level platform and then are winched into position. Each clamp has five holes, which bolts are put through to sleeve the clamp around the piling. Once in place, the bolts are torqued down to approximately 300 foot-pounds. This process is then repeated until each piling is sleeved with a circular clamp. Along with the bolt holes on the pile clamps are holes for the placement of lag bolts into the pile itself. This provides extra security to prevent the clamps from sliding down the piling when the bridge is eventually jacked up for replacement of the cap. While we're here, I'd like to show you that this moisture coming through the deck and this crack above my head here, that's where the expansion joint is. It allows the moisture to run down across the stringer, stand on top of the cap here, and you can see moss growing on it, and that's another indication of rot. This white stuff here is a good indication that's a good place to start rotting. If we have a weather check or a crack up here, water will seep down into this cap, and it'll stand there and eventually rot. I can see by looking at this right now, we have crush starting in this cap. It's where the weight of the deck is coming and pressing on this cap, and it's pushing it together. That's a bad sign. It's a good thing we're here to change this. Right now we're going to measure the distance between the top of the clamp and the bottom of the stringer. We have to put a 13-inch jack on top of the clamp, and we slide in a 42-foot-12-inch false cap. We need enough distance between this clamp and this stringer to allow for both of these parts. We always go at least 27 inches so that we have extra room to shim between the cap and the stringer because of the belly in the cap and the crown in the bridge. Working together as a single unit, the 22-bridge crew begins to hoist the 42-foot-12-inch false cap into place. Distance between the crane operator, the supervisor, and those on the staging platform are fluid and begin moving the false cap into its tight quarters. Prior to hoisting the beam, rollers were placed on the pile clamps to aid in sliding the beam into place. In the past, moving a beam this size could have proven to be quite a wrestling match. But with the use of the pile clamps and rollers, the false caps can be slid into place with little or no problem. Working with the precision that comes with practice and experience, the crew rolls the beam quickly and smoothly to its final mark. Following the placement of the false cap and the securing of it in place next to the cap scheduled for removal, a total of 10 55-tonne jacks are placed on the pile clamps to be used in lifting the bridge deck. The jacks are paired so that one person can operate the jacks at once. All of the jacks are operated simultaneously to lift the bridge deck all at once to prevent cracking of the deck. The jacks are lightweight and can be placed by one person in contrast to the old-style jacks that require two individuals to place them. As a safety precaution, when the jacks are fully extended, a lock ring is spun into place on each jack once the deck has been lifted to the needed height. These will hold a jack in place even if its hydraulics should fail. The bridge will be jacked up approximately an inch and a half. The pins that hold the cap to the pilings, which come through the deck and stringer, will be burned off. Watch that hold! Watch out! Here to the burning process, the old mastic has been removed and as the torch cuts through the bolts on the pile supports, a crew member stands by, ready with fire suppression measures. The next step is to lower the cap down and up on the stringers, they're usually nailed to the cap so we'll have to go through and burn all the nails off. Once that's done, it's ready to remove and pull out. We've installed these cap rollers that the bridge crew came up with. The change is fairly rapid and involves moving the old cap laterally off of the piles and onto the rollers with the use of a cumulon. Along with the crane operator on the top of the bridge, the crew pushes the beam onto the rollers and out from its old location. With the use of the rollers in place on the pile clamps, the massive weight of the beam is distributed so that it is easily moved. The removal of the old pile cap involves readjusting the crane's boom line several times while the pile clamps and rollers continue to bear the weight of the beam. But once the line is to the midpoint of the beam, the operation moves without pause or hesitation. The most critical phase of the operation occurs after the old cap is out and before the new cap is secured in place. The new cap is essential at this time. Essentially, getting the new cap into place is a reverse of the removal procedure. The new cap is hoisted to the rollers and pushed on to the rollers then into place. However, due to the taper of the new beam and the fact that the old beam has had some crush in it, it is not always as easy as it seems to get the new one in place. Occasionally it means jacking the bridge deck up just a little bit higher. Keep it. We're going to have to jack this up because I'm on the outside stringer. The jacking process is minimal though and results in the quick lift needed to get the new pile cap past the outside stringer. How much? Once the new cap is in line on its rollers, it is pulled into alignment with the bridge piling. Once it is in alignment, it is lifted with the port of power and new mastic is placed on all of the piles. After each pile has mastic in place, it is time to lower the deck. Replace the old cap with the new cap. We've set the deck back down. Now we're securing the cap to the bridge. We'll use this type of bracket here which attaches to the outside stringer and to the cap with lag bolts. We use a three or four inch lag. On the piles themselves, we use an angle iron like this. We place it like this and lag that to the pile into the cap. And that pretty well keeps it secure. Our next step in phase is we'll drop our clamps and it's take the deck off and move our needle beams to the next bend. Replacing pile caps seems like a relatively straightforward process. But as members of the Salem Bridge 22 crew stated, each job is unique, demanding its own specialized approach and should not be attempted by amateurs.