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ABI's Technology Prevents Change Orders

April 2019

Visual inspections are the fastest and cheapest form of non-destructive testing (NDT), making it by far the most commonly used method. However, visual inspections are incomplete and will not detect any internal damage. Making bridge management decisions using only visible deterioration (cracking, patching, spalling, etc.) can lead to costly change orders.

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ABI’s Rapid Automated Sounding (RAS) and Advanced Deck Imaging (ADI) systems provide the most comprehensive bridge deck inspection tool available to DOTs. The ADI system performs a rapid imaging inspection of the bridge deck, locating all cracks, patches, spalls, or other marks visible on the deck surface. At the same time, the RAS system performs an automated chain drag and quantifies any delamination located beneath the deck’s surface. This new inspection tool helps DOTs budget for maintenance and repair without being blindsided by change orders.

 

The maps below present bridge decks where the overall deck condition would be misrepresented if a traditional visual inspection was the only performed test. Delaminations are shown in red, patches in orange, and cracks are in black (only cracks >3mm are plotted in these maps). Note that all damage shown in the maps would be detected by visual inspection except for the delaminations (shown in red). These delaminations can only be detected by more involved inspection methods such as chaining.

The bridge shows significant cracking, especially in two of the lanes. However, there are almost no delaminations (only 2 sq. ft.) despite having similar crack patterns as the previous bridge. This bridge might be slated for repair solely based on the level of cracking when in reality the amount of delamination is not significant.

This bridge shows a textbook case of bridge deck deterioration. The damage develops as you might expect: significant surface cracking in the wheel paths that likely led to delaminations.  Despite the predictable deterioration pattern, an inspector judging this bridge solely by visual indicators would still inaccurately estimate the delamination beneath the surface of the deck.

This deck appeared to be in great condition based on visual indicators. There was very little patching, no spalls, and no wide cracks (greater than 3 mm). It seemed that the deck was in excellent condition. Despite this, the RAS system found that 11% of the bridge deck was delaminated. If this deck were slated for repair after a visual inspection, there would likely be large change orders. Possibly worse, the deck would be skipped for repairs and allowed to deteriorate further without necessary maintenance. This may be the reason that it reached 11% delaminated in the first place.

Until now, DOTs have been forced to rely solely on visual inspections for most of the budgeting decisions they make for bridge decks. The RAS and ADI systems provide DOTs the accurate information needed to make planning and budgeting decisions, preventing change orders and saving money.

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For another example of how ABI helps improve bridge management, click here.

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