Onsite Innovations

Regional Projects Put Newer Site Equipment and Technology to Task

by Diane Greer

Project teams across New York, New Jersey, and Connecticut are using new techniques and technologies onsite – often aiming to trim schedules and save money.

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Monitoring Data Onsite in Real Time     

 It has always been one thing to take all of the measurements that engineers and contractors need to assess a construction project’s impact on adjacent structures, underground structures, or bridges – and then quite another thing to actually sift through that data for the results.

But now, project teams are warming up to technology that automates data acquisition and dissemination from onsite instruments and produces results in real time. Over the past five years, more projects – particularly ones with construction schedules exceeding six months – are employing the new data tools thanks to engineers advocating its use and developers or contractors embracing its benefits, says Joel Volterra, geotechnical consultant at Mueser Rutledge Consulting Engineers of New York.

The new systems permit geotechnical and structural monitoring from remote locations and provide real-time notification via e-mail, Web sites, or pagers. That means project teams can find out right away when site activity triggers results that exceed pre-established thresholds, Volterra says.

Today, most monitoring instruments – including ones that measure short-term vibration from equipment and blasting or longer-term movement from geological or structural shifts – are equipped with data acquisition units, which store measurements and permit engineers to program the frequency of readings and notification thresholds. But project teams have only begun tapping the potential of these systems in recent years.

Volterra says even manual optical survey equipment for movement monitoring, a 100-year-old technique, now has data acquisition capability.

The monitoring equipment either directly connects to computers at the job site or it transfers data via modems or wireless connections to password-protected Web sites for dissemination and broadcast of real-time notifications.

Mueser Rutledge is using the real-time system for its work on New York Law School’s $190 million expansion project in Manhattan’s TriBeCa district. The firm has set up about 40 instruments, including tilt sensors and seismographs, to monitor adjacent structures and underground tunnels for New York City Transit’s 1, 2, and 3 subway lines, which run near the project site on West Broadway.

On a daily basis, the instruments transfer collected data to an onsite computer, and results exceeding a programmed threshold immediately trigger an e-mail.

“We receive a notification within seconds of an event occurring,” Volterra says. “A flashing light system also simultaneously alerts onsite personnel of a recorded event above the threshold.”

The technology also allows remote monitoring, but accurately evaluating the data often requires the project team to keep high-quality construction records that outline all onsite activities around a monitoring station that could affect its readings, Volterra says.

“You cannot truly interpret the data without knowing what has been done in the vicinity of an instrument in the past 24 to 48 hours,” he adds.

High-Definition Scans for Surveys 

The process of capturing precise site dimensions and flagging obstacles that could get in the way of a construction team is getting easier with the evolution of high-definition scanners.

Sampler: Manufacturers of High Definition Scanners • Leica Geosystems, San Ramon, Calif. - www.leica-geosystems.com • Trimble, Sunnyvale, Calif. - www.trimble.com • Riegl, Orlando, Fla. - www.riegl.com • Z&F, Duquesne, Pa. - www.zf-laser.com

Site surveyors are finally mastering the benefits of these scanners for construction. While the technology has been around for more than a decade, engineering firms first began to use it about five years ago, with sporadic quality in the results, says Kenneth Stigner, vice president in New York for Stantec Consulting of Edmonton, Canada, which he joined when his former firm, Vollmer Associates, was acquired earlier this year.

High-definition scanning combines a digital camera and laser measurement equipment to capture three-dimensional images of objects. The technology has improved especially over the last two to three years thanks to new software and more powerful computers to manage the data, Stigner says.

The tripod-mounted equipment first photographs the object to be scanned with a digital camera. Based on the image, the high-definition scanner sends out a laser beam and collects three-dimensional data points at specified intervals while rotating horizontally and vertically.

“Once the information is collected, you can view the 3-D object, rotate it 360 degrees and take measurements,” Stigner says.

The technology also allows designers to define collections of points within a scan as surfaces, lines, or objects and then export the data to CAD software.

The technology offers time savings, Stigner says. It recently allowed Stantec to scan a pedestrian bridge, a Metro-North Railroad track, and an adjacent highway in New York City in two days, much faster than the week it would have taken using conventional techniques.

The scanners are also useful for documenting older buildings with missing or poor-quality as-built drawings. The technology eases the collection of interior measurements by accurately capturing dimensions of rooms that are not perfectly square, while also recording outlet, fixture, and switch placements.

Yet another aid is how engineers on a project can return to the original scan for additional information instead of having to send a survey team back to the field.

“This is a big cost benefit,” Stigner adds.

Scanning also permits measurement of inaccessible objects, which on the Metro-North job eliminated the need to hire – and pay – flagmen.

“We were able to pick up the top of rail elevations without going on the tracks,” Stigner says.

Cranes for Wind Turbine Installation   

With the wind-power sector expected to gather strength in the coming years as an alternative, renewable energy source, manufacturers have developed new crawler cranes to facilitate wind-farm construction.

Big Crane, Big Reach: The 16000 • 440 tons • Basic boom has 98 ft of reach that can be enhanced with a luffing jib on boom lengths between 78 ft and 275 ft • Maximum main boom available - 315 ft • Maximum allowable combination of main boom and luffing jib - 433 ft • Capacity with the luffing jib - 165 tons • Hoist Speeds - up to 697 ft per minute More details in Cranes Today

The typical new wind farm houses anywhere from 100 to 300 turbines with each unit reaching 275 ft into the air and weighing 160,000 lb, says David Schwalm, executive vice president of JPW Riggers of Syracuse. Those lofty requirements are within the reach of the Manitowoc 16000 crawler crane, which lifts 440 tons and features a 157-ft main boom and 275-ft luffing jib.

“They were built specifically with the latest technologies and computers to hoist a windmill,” Schwalm says.

Manitowoc is the one of the largest crawler crane manufacturers, Schwalm says. Other leading firms in the market include Terex-Demag of Germany, Liebherr of Germany, Tadano of Japan, and Kobelco of Japan.

On flat terrain and under good conditions, the crawler cranes can erect up to four windmills a day, Schwalm says. Using computer screens in the cab, crane operators can program the radius, height, and weight of the load, allowing only that person to move the load within the specified radius.

“It helps keeps mistakes down and is a wonderful safety factor,” Schwalm adds.

JPW is using the Manitowoc cranes on wind farm installations across the country, including the Maple Ridge Wind Farm in Lowville, N.Y., where PPM Energy of Portland, Ore., and Horizon Wind Energy of Houston added 75 turbines last year. 

And demand for the new cranes is high. “If you want to order one now you have to wait two years,” Schwalm says.

New Pile-Load Testing Techniques 

New York City’s new building code, which municipal officials were aiming to ratify in early summer, is expected to bring various, long-overdue upgrades to the business of building in the five boroughs. And one proposed advancement is the ability to use alternative pile-load test methods, says Joel Moskowitz, a partner at Mueser Rutledge.

“There is great economic benefit to be gleaned from new techniques and test methods that can adequately replace what is currently required in the building code,” he adds.

The testing is essential to verify the load-carrying capacity of individual piles. Conventional static pile-load testing techniques apply an axial load atop a test pile, using one or more hydraulic jacks. But the technique is time-consuming and expensive, Moskowitz says.

One new technique that is gaining use outside of New York is a load-testing device from Singapore-based Statnamic. The device places a weight over a pile within a pressure chamber. Burning solid fuel within the chamber increases the pressure and exerts upward force on the weight, accelerating it upward and creating an equal and opposite force that >> pushes down on the pile.

The method is particularly useful on projects requiring a large number of pile tests, and it was actually used in New York on the construction of the AirTrain for John F. Kennedy International Airport, which, as a Port Authority of New York and New Jersey project, did not fall under purview of the city building code. The 8.1-mi AirTrain began service in 2003.

“The Port Authority permitted us to bring the technology to New York because the project required a large number of pile tests,” Moskowitz says. “The method sets up quickly, allows multiple tests in a day, and can be calibrated against conventional static tests to allow you significant economy in pile load testing.”

Subsequently, the city’s department of buildings accepted the test on other jobs, but only on a pilot basis.

Another device, Fundex’s Pile Load Tester, employs a controlled drop of a large weight on the pile. Dampening springs attached to the bottom of the weight diffuse the force of impact and extend the loading duration. The tester can be calibrated against conventional tests.

Mueser Rutledge was allowed to use the equipment to test piles at the Hunts Point Fish Market in the Bronx, an $86 million, 400,000-sq-ft facility that the city built to relocate Manhattan’s Fulton Fish Market in 2005.  The technology allowed testing of two piles a day, instead of the one test in three to five days under old testing methods, Moskowitz says.

While the new New York City code will not fully adopt the newest technologies, it would take steps in the direction of time-saving testing techniques. The new techniques have a proven track record in certain conditions based on use around the country, Moskowitz says.