In designing bridges, highway officials have in the past been most concerned about the traffic that will cross them. Now, Seamen’s Church Institute (SCI) is also helping them think about the traffic crossing beneath them.
With increasingly realistic simulations available, SCI has worked with transportation offices in Kentucky, Iowa, West Virginia, Louisiana and elsewhere to determine bridge location and pier configuration and placement so as not to interfere with inland waterway navigation.
“What Seamen’s Church has allowed us to do is go in with two or three options,” said Keith Todd, spokesman for the Kentucky Transportation Cabinet’s (KYTC) district 1 office in Paducah, Ky. “They have pilots come in and go through two or three scenarios.”
Todd credited SCI for help in planning for a new Interstate 69 bridge over the Ohio River between Henderson, Ky., and Evansville, Ind., for the U.S. 60 bridge over the Green River in Spottsville, Ky., and, more recently, planning for the U.S. 60 bridge over the Cumberland River in Smithland, Ky. Although SCI’s simulator involvement in some cases was years ago, many of the bridges are now getting close to construction, Todd said. Bidding for construction on the Spottsville bridge should begin within the next month to two months, Todd said. The Smithland project should be let for bid in February. The I-69 project is still years away.
KYTC officials have seen such benefit from SCI’s simulations that they are already asking for assistance in the planning for another major bridge crossing. KYTC held public planning meetings in September for the construction of a new U.S. 51/U.S. 60/ U.S. 62 bridge connecting Wickliffe, Ky., to Cairo, Ill., over the Ohio River and near the confluence of the Ohio and Mississippi rivers.
“It just provides a lot of information to the design staff as they move along the process for these new bridges,” Todd said, adding, “It may be 10 to 15 years before we get to the point of construction, but we’re getting lined up to do that early design work.”
Matthew Hyner, simulation and database manager for SCI’s Center for Maritime Education in Houston, Texas, explained more about how the simulations work.
The bridge’s engineering firm generally provides a few different potential bridge alignments that it believes are feasible, then has mariners test them in the simulated environment.
“The bridge engineer can receive real-time feedback from the mariners on what does and doesn’t work and why,” Hyner said. “We’re not only simulating how the towboat drives. We can bring in current data generated by mathematical algorithms that accurately predict how the towboat will handle in the water and through the bridge piers during different river stages.”
Other major bridges SCI has consulted on in recent years have included: the Interstate 74 bridge over the Mississippi River in Quad Cities, Ill.; East End and Downtown Ohio River bridge projects in Louisville, Ky.; potential placement of a new Mississippi River bridge in Baton Rouge, Louisiana; the Sunshine Bridge connecting Brook County, W.Va., and Jefferson County, Ohio; and the Iowa 9 bridge over the Mississippi River in Lansing, Iowa.
Simulation technology has improved in the past year or two to the point where the simulations also include river depth, the shape of the river bottom at the potential bridge site and the river currents at the site, Hyner said. Experienced pilots and captains generally run the simulations both at normal water levels and during simulated flood conditions.
“Identifying issues and crafting solutions in a simulator before spending millions and millions of dollars significantly reduces risk and is just a smart business practice,” Hyner said.
In the case of the Smithland bridge, Hyner said those simulations saved the contractor both time and money. The engineer’s initial thoughts on pier placement turned out not to work.
“We saw that on the second day, so—on the fly—they gave us some different plans with different placements, and we were able to put those in the simulator and create some new plans,” Hyner said. “In the end they decided we’ve got to put them on land.”
Todd said once officials could see the winding lower Cumberland River, near where it joins the Ohio, they understood the need for the piers to be placed on dry land during normal water conditions and could justify the expense of more expensive building methods to budget-conscious state legislators.
“It saved them eight months of design work,” Hyner said.
That was especially important since the bridge is such a major undertaking, Todd said. The $45 million, continuous-truss bridge is expected to take two to three years to build once construction begins, most likely in April. The new bridge is being built just downstream from the existing structure. The work should cause only minimal disruptions in river traffic, Todd said, adding that it will be comparable to when KYTC built the nearby U.S. 60 bridge over the Tennessee River in Ledbetter, Ky. That bridge opened in July 2013.
Hyner said the consulting work on the bridges ties in nicely with SCI’s mission of improving mariners’ lives by focusing on safety improvements. “The main reason why we’re doing these is a focus on mariners and making sure the waterways are safe and navigable,” he said.