MONDAY, MAY 15, 2017
By Robert Ikenberry
|We’ve all heard the real-estate cliché: “The three most important things about selling a house are location, location, location.” That’s because when most of us start thinking about buying a home we start with the neighborhood. Where do we want to live? What’s the commute to work? What kind of schools will my kids be able to attend? How much can I afford to spend? What’s the access to shopping and transit? And so forth.
Realtors focus on location because most of the other features of a home can be adjusted. You can remodel a kitchen, you can upgrade insulation or improve windows, you can change the horrible yellow color and you can plant bushes to obscure the rusting cars in the neighbor’s backyard. But you can’t generally pick the house up and move it!
Bridge-painting jobs should have a similar mantra: Access, access, access.
You can make a lot of adjustments to your crews, equipment and work methods, but if you don’t have good access to the structure, an efficient project is impossible. Therefore, you can’t just subcontract out the access and forget it. Different trades have different access needs. What works for ironworkers or electricians won’t work for painters. You need an access system designed specifically with your work scope in mind and overseen by someone experienced in the means and methods of bridge cleaning and painting.
First, you need to get really close to the steel for effective painting. Three feet away might as well be a mile. “Spitting distance” isn’t painting distance. Abrasive blasting might be a little more “hands-off,” but to really inspect, stripe, prime and finish-paint a steel structure like a bridge, you not only need to reach out and touch it, you really need to be able to “hug” the members.
Complex shapes and interiors of laced members are common on bridges. You need to get at them from both sides. And they have lots of edges, nooks and crannies that need direct attention and visibility from every angle. Plus, you need that access at every level. You must be able to reach around to coat edges, bolts and rivets, to reach through to coat interior surfaces, and to reach in and around to coat the interior edges, rivets and bolts. Touching the outside surfaces of a complex member is just not close enough.
Scaffold systems have generally been designed with a 6-foot, 6-inch level spacing, and that’s just about right for painting access. Certainly, 8-foot levels are too tall. In many instances, you really need to be able to get your head above the highest ledge or beam flange, so you can see over and down onto the inside edge. With a 6-foot, 6-inch spacing you can generally reach down from above for that top foot or so and see over the edge of a ledge up to about the 5-foot, 6-inch level, so that works pretty well. Plus, you can probably reach up to the bottom few inches of the members on the next level, where workers on the upper level can’t really see to reach around and under. There always needs to be a “reachability” overlap between the scaffold levels for true coverage.
When I say you need to be able to “hug” the steel, this goes for vertical columns and posts as well. You need to be able to reach them comfortably from both sides with good overlap, so that all the nuts, bolts, rivets, welds and edges can get attention from all directions.
Remember this height limitation when you’re designing platforms under the decks of bridges as well. If you can walk under the stringers of the bridge without ducking, your platform is too low. Stringers are typically 18 to 24 inches, and you need to be able to reach up to the top flanges and coat around the bolt or rivet clusters at their attachments. That means being able to reach up so that the back of your wrist—not just your fingertips—can touch the the underside of the deck of the bridge. The time you lose crouching down to stoop (or even crawl) under 4-foot floor beams that are only 2 feet, 6 inches above the deck is worth it when you have to work on the top flanges of the floor beams and stringers.
Remember, for really good access to the steel on a bridge, you don’t just need to be able to reach out and touch it: You need to be able to really wrap your arms around it.