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WaterUnder theBridgeContending with water as deep as 100feet and currents that reach up to 8feet per second, Civil Southeast’s teamon the Indian River Inlet Bridge (IRIB)project in Rehoboth Beach, D.E, washard-pressed to find a way to constructa 2,600-foot-long cable stay bridge thatincludes a 900-foot span over the inlet.The solution came in the form of twothree level, moving pieces of equipmentknown as form travelers.Cortez Flips the SwitchAt more than 6,100 feet of elevation and averaging less than 13 inches of rain every year, the Cortezoffice sees plenty of sun. Now it’s begun to harness some of that solar energy.Skanska’s property in Cortez is now sporting a $1.5 million, 258 kilowatt photovoltaicsolar array, set in 15 rows and comprising 1,260 individual photovoltaic panels. Theinstallation is on 2.5 acres, adjacent to the office and equipment shop.“Our system includes GPS telemetry that will allow each panel to pivot to followthe sun across the sky,” says Estimator Keenan Willbanks, who served as projectmanager for the installation. “That makes the panels 30 percent more efficient than ifthey didn’t move.”While designed and engineered by an outside solar firm, the Cortez team did all ofthe construction work, from initial site work to installing the posts and panels.“There is the obvious green aspect to the project,” says Vice President David Sitton,“but there’s also a strong business purpose. We want potential clients to know that thisis work we not only say we can perform, but have the résumé and skill set to execute.This has already opened some doors to potential clients and projects.”When the facilities are using less power than what’s generated by the array, poweris fed into the local grid. Similarly, the office taps into the grid to account for neededpower in times of high demand. Safety fail-safes ensure that if the grid blacks out, thearray powers down to avoid electrocuting utility linemen making grid repairs.The end result will be a significant energy savings over baseline –and to the bottom line.“Using models where we assume the price of electricity stays the same, this shouldpay for itself in six years,” David says. “Of course if prices for power go up, it’ll pay foritself much sooner.” ◆Annually, powergenerated from theproject is forecastto be equivalentto saving:45,000 gallons of gasoline400 tons of carbon dioxide1,000 trees“The current in the inlet is so fast that using a barge tolift segments into place wasn’t a viable option,” explainsEngineer Frank Spalt. “But with the travelers, everything iscompletely supported by the bridge itself.”The travelers clamp to the bridge using a system ofrollers and bogies to keep it balanced while moving. Whenin casting position, the travelers cantilever out, providinga platform on which forms can be constructed. While theyremain stabilized during the launching process and move ata slow pace, the team instituted certain safety precautions.“When moving the travelers forward, the handrails areremoved from the bridge deck and the equipment dropsabout 7 feet,” says Construction Manager Peo Halvarsson.“This exposure requires worker to wear fall protection,and crew communication is key since people are workingwithin the structure as well as on top of it.”But the benefits outweigh the risks.“The travelers dictate the cable stay installation. It’s abalancing act because once the travelers move to the nextsegment of the bridge, they must be counterbalanced frombehind with the installation of the cable,” Frank says.In all, nine cable stays on each side of the four pylontowers have been installed and four more are on their wayin to help the travelers complete their current segments. Intotal, 76 out of 152 stay cables are in place.The project team has begun casting the bridgeover the inlet, and with approximately 500 feet left togo, the travelers will certainly play a huge role in thisfinal phase of construction. ◆12 coast to coast coast to coast13