Streamliner BridgeU.S. 169 over the East Fork of the Des Moines River
Of the three aesthetic bridge design theme options presented to a group of Algona city officials by the Iowa DOT, the Streamliner Bridge concept was the hands-down favorite. The city already had a strong association with its railroad heritage, and its slogan, “Algona - On the Right Track”, capitalizes on rail imagery.
The Streamliner Bridge concept benefits from the movement of motorists past the structure, which gives the impression of a passing train. The traffic barrier surfaces are articulated to appear as rail cars, which — though stationary — take on a perceived kinetic aspect through the movement of the observer over the bridge.
The abutment wings sweep up from the ground in progressive arcs to form the base of the signature railing end posts. Concrete is carefully sculpted in subtle layers and rustications to convey the form of the ultimate Art Deco expression in the history of American transportation: the Streamliner locomotive. Sine-wave form liners create smooth linear corrugations not unlike those found in the metalwork of Deco-inspired rail cars. The silver grey, bright yellow and vivid red color scheme recalls the signature colors of the Hiawatha rail line, famous for its beautiful mid-20th century locomotives. Custom-designed ornamental steel offers a whimsical finishing touch in fine detail, while providing the perfect setting for light-emitting diode (LED) accent lighting.
The choice of pedestrian railing was made to promote the Streamliner theme. Long, continuous horizontal lines were achieved through the use of multiple pipes connected by plate steel posts, with no expression of the posts on the pedestrian side of the railing. The result is lines uninterrupted from end to end when viewed by trail and sidewalk users. The separation barrier’s steel-pipe railing is also designed to be faithful to the bridge’s architecture, with its splices and stylishly-curved steel plate posts synchronized with the “rail cars” of the barrier.
The bridge’s two river piers display the same character of playful curvilinear forms and surfaces as established by the abutment wings, but on a more expansive scale. Form liners in the same sine-wave pattern were used, but in larger sizes appropriate for both the massive shape and the more remote viewing opportunities. Secondary concrete pours created sculptural “bumpers” at each end of the piers where they meet the water. The swept-wing emblems found on the end posts above the deck are echoed in the pier stems with a bright yellow accent.
The Streamliner Bridge is uniquely aesthetic and is sure to become a signature structure for the community. Its comprehensive, economical and imaginative design stands as a model for similar projects of strong local interest in other cities and towns across Iowa.