Surveying Archives - Infrastructure Digest

High-Tech Railway Monitoring Helps Save $13 Million

One component of the plan emerged early as particularly challenging and troublesome. Work on one section of the TBI would require installation of 162 feet of 12’x9′ box culvert, which in turn would require removal and replacement of 120 feet of rail operated by BNSF, and in the area of track affected, the top of the sewer tunnel was just five feet beneath the top of rail. Understandably, BNSF was concerned about the effect of any work in the area. This is a very busy section of commercial railway–30 to 40 trains daily–and shutdowns are almost unheard of, and stoutly resisted by BNSF. Still, BNSF agreed to an unprecedented 30-hour suspension of rail activity.

To further complicate work in this section, high groundwater and difficult soils made subsidence an issue, and railway settling was a real concern even without construction work. To allay BNSF’s concerns, Barr devised a technically progressive subsidence monitoring system based on 250 track-mounted prisms and two Leica TM30 optical monitoring sensors. With this worked out, the 30-hour “Big Dig” was set to proceed.

Why should you read this? Monitoring is getting easier, cheaper… and more important. (full disclosure—I wrote this awesome article) The American Surveyor, January 2015

A Huge Success Story: Real-Time Monitoring A Hit Down Under

The site already includes a very busy railway corridor, a bus tunnel and a historic building. This required Watpac to provide assurances to the owners of those assets — Queensland Rail, TRANSLink and the South Bank Corporation, respectively — that the 12-month construction process would not damage them. With this in mind, the company needed a geospatial solution to monitor the work in real time, non-stop, from start to completion, and alert it to any deformation that could lead to a collapse and endanger lives — so that trains and busses could be stopped before they entered the hub and construction personnel could be evacuated in time.

Why should you read this? The realities of increasing litigation and improving monitoring technology more or less dictate that some sort of monitoring will be coming soon to your town. POB, January 2015

The Curt Brown Chronicles: Engineers and Surveying

“Most engineering colleges offer training in computations, mapping and instrumentation, but little or nothing in surveying law. A man may be a beautiful technician, a skilled mathematician, and an expert at making measurements, but of what value is his skill it he does, not know where to place a legal property corner? Almost 100% of the fault we find with the men we employ is their ignorance of where to place property corners. The objection is frequently raised that the subject of land law is not engineering. But is that true? Everyone is expected to obey the law and everyone is presumed to know the law. The property surveyor is licensed to set property corners and he is expected to set them in accordance with the correct principles of law. He is not practicing law; he is merely obeying law in the same fashion that you or I do when we obey the speed limit. And if land law is never engineering, why has the engineer from time immemorial had the task of locating right-of-way lines and property lines for his fixed works?”

Why should you read this? Short editorial on an important continuing controversy. The American Surveyor, January 2015

POB Market Study: Who Is Spending What, Where and Why?

“To provide detailed information on expected spending in the next year on equipment and software, BNP Media’s market research division worked with the staff of POB magazine to conduct a market study this fall. And just who did we ask? The majority of our 2014 study respondents — 54 percent — work directly in surveying/geomatics. Another 25 percent are in corporate/executive management, while 10 percent are in general management. On the whole, a whopping 75 percent of our study respondents have been in the business for more than 20 years.”

Why should you read this? Why did Willie Sutton rob banks? “Because that’s where the money is.” Those working directly in surveying and related industries will want to know where and how money is being spent on surveying this year. POB, December 2014

Pix4D Mapper

“Pix4D Mapper is the software I’m writing about here. This insanely cool program will import images from any camera, along with GPS coordinates and external point clouds. Without much input from the user, it will create a complete 3D model. The model can then be exported as a 2D orthomosaic image, a 3D digital terrain model (DTM), or a 3D point cloud. That’s almost three products in one.

Here’s my take on the product just from talking to Pix4D about it and experimenting myself. (Full hands-on test projects are forthcoming here in print, and Pix3D’s test project is on”

Why should you read this? Well, you could use a $90,000 laser scanner to create your 3D model… or your iPhone. It’s not that simple, of course, but not every model needs to be high-res, and this approach does work. Of course, we’ll probably have scanning apps in our smartphones before too long… XYHT, December 2014

Civil Engineer Places Two-Million Dollar Home on Wrong Lot—This Was Not Land Surveying

“Four Twenty proceeded to build a magnificent 2,400 square foot, three bedroom residence with a septic system and a sweeping driveway, all in reliance on Carrigan’s plans. When the project was completed, Four Twenty entered into a purchase and sale agreement to sell the property for $1.9 million. Before completion of the transaction, the buyer commissioned Richard S. Lipsitz, a Professional Land Surveyor and the president of Waterman Engineering Company to perform an independent survey of the property. Lipsitz performed a Class I survey to verify the location of the property lines and to ensure the marketability of the property. Upon completion, Lipsitz’ informed the buyer that the home was built on the wrong lot and was instead, located entirely on the Nulman Trust Property. The buyer naturally terminated the purchase agreement.”

Why should you read this? You may have heard this story, at least in broad outline. This is an excellent article that provides details of the mistakes made, and how the liability fell out in court. Also, for land surveyors, more support for better survey standards for pre-construction surveys. The American Surveyor, November 2014

Tunnel Beneath the Bay

“The new pipe will be installed in a dedicated tunnel constructed roughly 100 feet below the bay floor. Known simply as the “Bay Tunnel,” the new conduit is 15 feet in diameter and more than five miles long. The digging is done by an earth pressure balance tunnel-boring machine (TBM), a type of tunneling system well suited to the dense clays that make up much of the bay floor. To launch the TBM, the project’s tunnel contractor, Michels/Jay Dee/Coluccio Joint Venture (MJC) excavated a shaft 58 feet in diameter and 124 feet deep in East Menlo Park on the west side of San Francisco Bay.

According to MJC Project Engineer Ed Whitman, the TBM and launch shaft are normal parts of a major tunneling project. But the Bay Tunnel contains an important distinction from Whitman’s past projects. In other TBM-built tunnels, several vertical access shafts (Whitman calls them “manholes”) are built at intervals along the tunnel. In a similar sized-tunnel that Whitman worked on in Ohio and California, manholes were spaced roughly 1,000 to 1,500 feet apart. Among other functions, the shafts enable project surveyors to connect geodetic control points on the surface to the control points in the tunnel, making adjustments and corrections as the TBM moves ahead. Because the Bay Tunnel is under a body of water, manholes aren’t possible. As a result, all the survey control (essential to steering the TBM) is tied to one end of the tunnel. “It’s like taking a five-mile shot off a 50-foot backsight,” says Whitman. “From the survey perspective, it’s not for the faint of heart.””

Why should you read this? If tunneling 100 feet under San Francisco Bay doesn’t get you interested… maybe you shouldn’t be in infrastructure? POB, January 2013

Sediment Mapping by Air

“Paradoxically, the effectiveness of the dam for sediment control has led to a serious issue confronting the reservoir: sediment deposition is reducing reservoir storage capacity and causing significant aggradation upstream within the Rio Grande channel. Monitoring sediment volume, spatial distribution, and rate of deposition is of paramount concern to the Corps of Engineers. Consequences for the operation and life expectancy of Cochiti Dam and Reservoir are at stake.”

Why should you read this? An interesting survey niche, and a look at an infrastructure peril you may not know much about. Aerial Mapping 2012

Crucial Post-tornado Imagery

“As we waited for the weather to clear, our crews began planning their flight lines. During this process, we made a decision that proved critical to the success of the project. We put word out to the Missouri GIS Advisory Committee (MGISAC) listserv about our plans and asked if anyone had a map of the tornado path. The response was remarkable. Within minutes, the Missouri National Guard and the State Emergency Management Agency (SEMA), both with boots on the ground, delivered remarkably detailed shapefiles delineating the path of destruction…

Working with a combination of Z/I Imaging DMC processing software and our own proprietary systems, the production team orthorectified the one-foot images first using the natural color bands and existing elevation data. Once the 40 one-foot exposures had been orthorectified, they were used to filter out some of the three-inch exposures that contained no damage as a means of expediting the remaining processing.”

Why should you read this? Weather events keep happening, and surveyors are often first responders, at least in terms of infrastructure. This is a good case study on rapidly gathered aerial data used to assess damage and plan reconstruction. Professional Surveyor, 2012

Invar—The Breakthrough for a Low Expansion Alloy

“The field test came in 1906 under the direction of Owen B. French when C&GS decided to re-measure six existing baselines: Point Isabel Base, Texas; Willamette Base, Oregon; Tacoma Base, Washington; Brown Valley Base, South Dakota; Stephen Base, Minnesota; and Royalton Base, Minnesota. Three existing 50-meter steel tapes 403, 405, and 406, and three of the new 50-meter Invar tapes, 438, 439, and 440 were used for the experiment. A fourth tape of each type was utilized as a check while the others were held in reserve in the event of damage. To calibrate the tapes, a comparator line was established in the tunnel joining two buildings at the Bureau of Standards. The line was repeatedly measured with the Ice Bar to ensure the probable error of the derived 50-meter length did not exceed +/- 0.03 mm. The steel and Invar tapes were then used to measure the comparator line at least four times each. All of the tapes were also standardized at the Bureau of Standards before beginning the field work to test strength and elasticity. During part of the standardization process, Invar tape 438 was subjected to one hundred reelings and unreelings, on several occasions, without showing any change in length. Another Invar tape, 437, was kept outdoors when not in use and subjected to a temperature range of 14° to 86° F. It also did not show any change in length.

At the conclusion of the field tests, it was found the Invar tapes could be handled and manipulated in identically the same manner as the steel tapes except for placing them on larger reels. The Invar tapes, when properly manufactured, were found to vary less than one part in 500,000 after six months of use in the field. Measurements could be made with the Invar tapes during the heat of the day and repeated standardization was not necessary. This was a savings of time in both the field and laboratory. Measuring with an Invar tape was therefore deemed superior to using a standard steel tape.” 

Why should you read this? This one is for survey geeks; the history of man’s attempts to accurately locate and measure points on Earth is fascinating… to some. If you’re one of us, this article on Invar tapes, by Jerry Penry, is catnip. TAS also offers a PDF version in magazine format. The American Surveyor, November 2012

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