Checking crystal bridges

April 2, 2018
Steuben County treats spans with labor-saving engineering and design tools

New York’s Steuben County is famous for just what you might guess: Steuben crystal. The maker of fine crystal animals, bowls and candlesticks took its name from the county, and its parent company, Corning Inc., took its name from one of Steuben County’s largest cities, where it is headquartered. Corning’s factory still makes the Pyrex cookware that made it famous 80 years ago, but since then the old glass works has become a global giant, churning out high-tech products like fiber-optic cable and the silica windows for NASA spacecraft.

At 1,600 sq miles, Steuben County is one of the largest counties in New York, slightly smaller than the state of Delaware. But it is largely a rural place, latticed throughout with rivers and streams with vineyards rolling among the Finger Lakes in the north and Amish villages nestled in the south. With few town-maintained bridges, the burden of taking care of the county’s infrastructure often falls upon the county department of public works (DPW).

The county has 678 miles of road to look after, and chances are that each of those roads depends on a series of large and small bridges to get across the streams that criss-cross the county. In all, the county maintains more than 700 of these bridges, about half of them smaller than 20 ft long.

“We’ve got a lot of water up here,” said Kent Longacre, a CAD specialist with the DPW.

To track and design bridge projects, along with other tasks such as realigning roads and rebuilding intersections, the DPW relies on Autodesk Land Desktop (Circle 921) and its companion products, Survey and Civil Design (Circle 922). With labor-saving engineering and design tools that are easy to learn, the department’s small staff is able to handle projects that it might otherwise hire out to contractors.

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Troubled water

Each year in the fall and winter, when the leaves are off the trees and won’t obscure the surveyors’ sightlines, the DPW inspects its bridges and selects a number of them to survey and improve. Using a Leica surveying gun that allows them to enter labels for features as they work, county surveyors measure the GPS coordinates of the banks of a river leading up to a bridge, including trees, buildings or other landmarks. They download their raw data into Autodesk Survey, which creates a field book and captures the labels.

From this data, DPW engineers can create a map of the stream with terrain features in a “real-world” coordinate system, adding in local watershed details if necessary.

“Land Desktop allows us to look at vertical profiles and sections of the river, which we can check against previous maps to see if the banks are eroding and need reinforcement,” said Longacre.

A bridge structure may need repairs if it has deteriorated or is skewed improperly along the stream, channeling water the wrong way. In a downpour, fast-moving water could overwhelm such a bridge, degrading its banks or even undermining the road surface above. If the bridge needs to be realigned or repaired, DPW engineers plan the improvements using Autodesk Civil Design, sometimes designing new concrete beams, sending the drawings out to a beam supplier.

“We’re one of the few counties in New York that does our own bridge design and construction in-house,” Longacre said.

In addition to bridges, the Steuben DPW regularly selects parts of its road system for safety improvements—flattening out stretches of hilly or bumpy road, extending sight lines, realigning dangerous curves. On a road where the surface has deteriorated over the years, causing the pavement to dip up and down, surveyors will take vertical measurements at intervals and then view the road’s topography. Using Land Desktop, engineers can create a digital terrain model of the road, looking at several profile cross sections—slices of the road they can compare with previous years. Land Desktop shows them precisely where the road has deteriorated and calculates how much fill the DPW will need to make it level and safe again.

The same volume-measuring features in Land Desktop allow Longacre to monitor how high the surface levels are rising from month to month in the county’s two landfills.

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Dangerous curves

Realignment work on road curves has several elements. Sometimes a curve will need to be “superelevated” so that its outer edge is higher, the same way auto racetracks have steeper banks around their curves. Banking the road this way allows a driver to move around a corner at highway speed without veering off into a ditch. Sometimes the angle of the curve is too tight or it is elevated on the wrong side due to the pressures of years of traffic; these flaws show up when engineers survey the road and view its topography in Land Desktop. Civil Design makes it simpler to design a realignment that brings the road up to various standards for geometry and sight distance mandated by the New York State DOT.

“Civil Design has variables for things like banking, speed tables and superelevations,” said Longacre. “It will automatically calculate the transitions in and out of the curve, the necessary angles and elevations, because the DOT codes and standards are already built in. That makes it a lot easier to do those calculations when you’re mapping out the realignment.”

The DPW also appreciates the ability to do what Longacre calls “what-ifs.” Autodesk Civil Design “allows us to do three or four different scenarios for changing a curve, which is a real benefit,” he said. “To help us make the right decision, we’ll do several models of the same road realignment. We just put different numbers into a table and [Civil Design] has an extension that will immediately adjust the drawing in front of you.”

After plotting and printing the different options, they show them to the agency’s chief engineer.

“We point to the particular positives of each, and he can choose the best one,” Longacre said.

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Having a central repository for drawings in the DPW allows different engineers and drafters to collaborate, building on other people’s work.

“We’re all networked, so one of us can call up the site plan from the database, rename it as a new file and use it for something he has to do,” Longacre said. “My colleagues here don’t have to design things from scratch on paper anymore; they can just work off my drawings, and vice versa.”

Another benefit of in-house design is that the agency’s maps are more accessible.

“For example, the other day the head of our road construction crews wanted to see a cross section, so he just walked over to the designer and she pulled it,” Longacre said. “If we had given the job to a consultant, we’d probably have to mark up a drawing and send it out, and it would take much longer.”

“The bottom line is, if we can do highway designs ourselves, we save the taxpayers money,” Longacre said. “And we’re doing a pretty good job of handling it ourselves.”