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Steel Shows Its Strength

Steel trusses and supports give an open feel to an award-winning transit center in Athens, Ga.

December 01, 2007 |

As the home of the University of Georgia and several other colleges and universities, the city of Athens, Ga., has always needed accessible public transit. In recent years, however, downtown Athens started running out of spaces for park-and-ride commuters in its historic downtown. Its bus transfer station around Athens City Hall was clogged with buses converging in parking spots along the street; bus patrons had to wait on sidewalks with no protection from the weather. Something had to be done.

Usually cities look to federal and state grants to cover much of the cost for constructing transit facilities, but the citizens of Athens decided to take matters into their own hands. In 2005 they approved a special-purpose local sales tax to build a new transit center, an aerial pedestrian bridge, and accompanying roadwork and infrastructure—all on a tight budget.

“We knew it was a fixed budget of $9.5 million going in,” said Lester Love, principal with project architect Niles Bolton Associates, Atlanta. “We planned for it within those constraints, but the client and the design team still wanted to evoke a sense of civic pride and strength of community.”

That strength has been communicated primarily through the use of open steel trusses in the main building, a canopied bus waiting area, and the pedestrian bridge, where exposed structural members coated with intumescent fire protection paint were used. Atlanta structural engineering firm Uzun & Case used ATIR's STRAP engineering software to design the canopies and analyze the truss design and Bentley's RAM software for the structural modeling of the building.

Major uplift and lateral wind forces on the bus canopies presented significant loading requirements. Sizing and reactions were exported directly from RAM into CAD drawings. Steel fabrication took place during the site development phase in order to have the steel trusses and supports delivered to the site ready for erection.

The steel structure of the Athens Multimodal Transportation Center was designed to be open and welcoming.

“From the beginning, we knew the canopies would have to be exposed steel,” said Larry McDowell, PE, senior principal with Uzun & Case. “The canopies took up a good portion of the whole structure, so it was a good material to use throughout the project.”

The 152-foot length of the pedestrian bridge posed another design challenge. The long span rested on relatively small building columns, and wind load was also a factor. “We had 12-inch wide flange columns, but we had to accommodate whatever movements we'd get from the bridge,” McDowell said. Wind load and connectors were all analyzed in STRAP.

Because an existing rail line had to stay in operation during the bridge's erection, the bridge was delivered to the site in two pieces and bolted together on-site by Atlanta general contractor Aldridge, Inc. There was no interruption of rail service.

Access for a commuter line that someday may connect Athens to Atlanta was also designed into the project. The light-rail line has not been built, pending funding.

The 9,500-sf Athens Multimodal Transportation Center has 17 bus bays that serve the University of Georgia bus service, regional bus lines, and Southern Stages bus service. Walking and bike trails are also connected to it.

The pedestrian bridge connects the bus transfer facility to a parking garage completed in an earlier phase of the project. The 646-space garage is shared with a nearby Athens convention and performing arts facility.

The Multimodal Transportation Center has attracted nearly two million riders since opening in August 2006. The project won an Innovative Design in Engineering and Architecture with Structural Steel (IDEAS2) merit award for structural design from the American Institute of Steel Construction.

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