THE PROJECT
In 1999, NYSDOT commissioned Erdman Anthony to perform a bridge replacement study on the Troup Howell Bridge. The highway, which has an ADT of 50,000 and carries Interstate 490 over the river and several city streets and ramps, is a major commuter route that connects the eastern and western suburbs to the center of the city of Rochester. After considering several potential design options at a public hearing, the community overwhelmingly chose the steel arch because of the main span’s ability to serve as a "gateway" or "signature" bridge that would frame the river and the city skyline. 

Erdman Anthony prepared preliminary and final plans, special specifications, and quantity estimates for the arch and approach spans. Our firm also performed three-dimensional structural analysis.

FEATURES/SOLUTIONS
Since extremely competent bedrock was located within 13.1 feet of the ground surface, the choice of a true, two-hinged arch was structurally and economically feasible. The new eight-span structure is 1,194 feet long with the centerpiece being a 433 foot long through arch span crossing the Genesee River. 

One design goal was to carry the river walks beneath the bridge, exposing the underside of the bridge to the public. Rounded floorbeam ends and a sculpted floorbeam met the desire for visual interest and proved structurally efficient. The rounded ends also house aesthetic lighting that, at night, shines upward to illuminate the underside of the arches and braces.

The bridge railing system was designed so that passengers in I-490 vehicles could view the surrounding area.

IMPACTS
A major project challenge was to detail plans for staged construction as traffic modeling indicated closure was not an option without creating gridlock on city streets. The three-stage construction process allowed for minimal disruptions during new foundation construction and as eastbound and westbound traffic was shifted to accommodate the demolition and replacement of those bridges.

The Frederick Douglass-Susan B. Anthony Memorial Bridge has, indeed, become a Rochester landmark and icon.