Imaging a safer future - No 25 - July 2020
Civil structure inspections have a distinct culture. Many field inspectors have been at their jobs for decades, bringing with them decades of experiential knowledge about what to look for, how to document, and what recommendations to make. Something that is shared in this culture details, in both the structural owner and consultants working environments. The integrity, accuracy, and validity of the data being presented in reports are undoubtedly critical in understanding the next steps, which probably include design recommendations. Questioning whether a road section should be paved this year or next, whether a pier section should be blasted out and remolded, whether a bridge deck needs a new overlay or no all of these decisions hinge on specifics that required a substantial amount of detailed investigation. Especially in prestressed concrete members, where just 0.2mm of crack width makes a huge difference in response measures.
Though written reports, an album of pictures snapped with an iPhone, and hand-drawn polygons in a CAD file can communicate detail, these methods of reporting all pass through at least two subjective filters: the first from the inspector themselves, and the second through the analytic team making the final design recommendations (who may not have been in the field themselves). While the experience and collaboration of many talented minds fuel inspection reports, some detail is lost in the written or verbal transfer of findings. The culture of pouring over inspection reports needs a bit of juice, and we think this should come in the form of more detail.
Subjective filters end up reducing what we are most reliant on detail. We have observed many external cases where the actual condition of the structure often becomes scrutinized in follow-up meetings, or the location and nature of certain deficient findings become convoluted. Taking advantage of strong development in image sensors, NEXCO has already been providing owners with scaled deficiency maps with imagery so clear, there is little question about the as-is condition of structures following their creation. The question - where was that crack again? - will cease to exist: all that is required is looking back at the maps.
Taking the concept of creating a digital replica a bit further, how can we preserve the collaborative culture of making design recommendations post-inspection? NEXCO is hosting deliverables online that can be notated collaboratively from anywhere. With an HD composite image of a surface in front of them, our team members can all discuss the same view remotely. A field team who just took data in Pennsylvania can upload it and look at it together with our team lead in Virginia, who in turn can invite the client to join in as well and offer comments. The possibilities are expansive, and so is our willingness to bring this service to owners across the US. To learn more about how we can create detailed and collaborative reports for your team, click the button below to visit our website.
To gain a better understanding of the volume and duration of roadway repair projects that have gone over expected time windows (and probably over budget), we took a broad look at news briefings from three local DOTs over the course of July 2020. We identified projects that reported continued road and lane closures and noted which project involved asphalt and concrete patching, inspection, or rehabilitation.
During July, we found an average of 25 publicized projects that impacted road users for longer periods than expected. The majority of these projects were delayed by a week or more, suggesting a scope that went a good deal over the original estimation. One major reason for the delays lies in a misestimation of the repair work during the inspection process.
Road patching projects offer an illustrative example. An inspection report comes back saying a 100mi stretch of road had recurrent spalling and alligator cracking, for instance. The inspection team and/or owner anticipate the costs for repair and bid out a patching project. The problem comes when the repair contractor pulls up a bit of asphalt and discovers there was extensive, undetected damage to the subsurface. Not to mention the total area of cracking and spalling has gotten worse since the first inspection and was under-estimated. Now the project is under-budgeted, and the road stays closed for an extra month.
Many state DOTs who have started to use in-house or contracted mobile scanners now know how this can be avoided: by calculating rather than estimating. Taking the total surface area of detections automatically or semi-automatically produces that magic number needed for repair projects, and helps keep projects on schedule, and in scope.
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