Think of it as stealth construction. On most major urban projects, long before the first bucket of dirt has been scooped, the first pile driven, even the first property corner verified, work, in the form of pre-construction survey and monitoring, has already been set in place. Critical for identifying existing conditions of adjacent properties be- fore work begins, then monitoring those same properties — and others — for movement after startup, these facets can be as important to a design build team as the project itself. In an ongoing project to add a third track to a ten-mile segment on the main corridor of the Long Is- land Rail Road (LIRR), Bronx, N.Y.-based Vibranalysis is undertaking that effort throughout the length of the $1.8 billion project. Utilizing an arsenal of total stations, optical prisms, and an abundance of geotechni- cal, structural and environmental monitoring sensors, the company is helping ensure that the “before” picture is documented and any “after” events can be quickly identified and mitigated. Working on the Railroad The LIRR’s Main Line, which runs the length of the island from Long Island City, Queens to Greenport, Suffolk County — roughly 95 miles — carries about 40 percent of the railroad’s current 308,000 daily rid- ership. A third track has been a subject of discussion since the 1940s but, for reasons ranging from fiscal concerns to resident complaints and everything in between, could never reach approval. Until this time around. “More than a hundred thousand people depend on the LIRR’s Main Line on a daily basis — people who are affected by any interruption in train traffic along that 10-mile stretch,” said Howard Jameson, Vi- branalysis’ vice president. “The expansion will be huge for improving service reliability on the line. However, this project covers a lot more than just the additional track, and we are providing instrumentation and monitoring services in several of those areas as well.” Indeed, the list of improvements covered under a larger $2.6 billion cost umbrella is sizeable. It currently includes the elimination of seven grade crossings; seven bridge replacements and modifications; im- provements at five passenger stations; replacement of seven electrical substations; improvements to existing parking facilities and construc- tion of an entirely new parking ramp; and 7.5 miles of sound/retaining walls. “Using monitoring gear on a job like this is essential,” said Jameson. “Anytime you are conducting an extensive scope of work adjacent to structures that are remaining active, you need to ensure that those structures react in the manner in which the way they are designed. And if they don’t, you need to be able to quantify that change and mitigate it immediately. We provide that level of information.” Third Track’s a Charm Surveying and monitoring play a key role in Long Island Rail Road’s much-anticipated main corridor track addition.
While extremely complex in practice, the science behind monitoring movement is actually rudimentary. A semi-permanently mounted total station measures angles and distances to optical prisms affixed to the structures being monitored. Software, bundled with the monitoring system, applies statistically-weighted adjustments to the measure- ments and outputs spatial coordinates for each prism. If the system notes a change in those coordinates, more than likely movement of the monitored subject has occurred. By comparing current and initially- gathered coordinates, the degree and direction of the movement can be determined. Surviving Lean Times Established more than three decades ago by Linda Socquet, Vibran- alysis began as a provider of vibration monitoring services and pre- construction inspections — primarily for controlled- demolition applications. “Linda Socquet started this business in mid-1980s in NewYork City — not the best time to be a woman in a startup construction-related busi- ness,” said Jameson. “But she was able to keep it going as a smaller, specialty firm focused on complex projects. For example: in 1998, when The Empire Theater building in Times Square was physically moved to a new location about 168 feet away, she was responsible for instrumenting and monitoring that structure as it made the trip. Her drive and motivation has been a key motivator, not only for employees of this company, but for other leaders in the industry as well. By his late teens, a growing interest in Vibranalysis led Jameson to pro- gramming and writing code that would prompt sensors to give results back through various logging pieces of hardware. “As I got older,” he added, “focusing on wireless systems, I learned more about the reasons for implementing specific sensors and the creative things you can do with them to overcome a challenging problem or situation.” Armed with a degree and a vision for growing the business, Jameson joined Vibranalysis in 2012. Much like Linda Socquet decades before, he entered the business in challenging economic times; the New York City area was still recovering from The Great Recession. He quickly realized things were not going to be as easy as he’d initially thought.
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csengineermag.com
july 2020
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