The bridge that carries South Lyon Street over Tonawanda Creek in the City of Batavia, NY was originally constructed in 1910. The bridge spans an area of Tonawanda Creek that is flood-prone, and by 1986, the bridge required replacement. It was removed and, as a temporary solution, a one-lane prefabricated Mabey truss bridge was installed on top of the original abutments. This “temporary” superstructure ultimately remained in service for 35 years, much longer than originally planned. The new steel truss bridge is built to meet current structural standards and provides a service life of 75 years. The structure is galvanized to maximize corrosion protection and minimize maintenance costs associated with painting the truss and is considered the key project element to achieve this goal for the County.

When the South Lyon Street over Tonawanda Creek Bridge Replacement project wrapped up this summer and the bridge was reopened to traffic following a two-year safety and construction closure, the City of Batavia, NY community received a substantial upgrade and a long-awaited reestablishment of a vital link between the West Main Street commercial district and the residential community on the opposite side of Tonawanda Creek. The structure is galvanized to maximize corrosion protection and minimize maintenance costs associated with painting the truss and is considered the key project element to achieve this goal for the County.

For the Genesee County Highway Department, the sponsor of the project, re-opening the bridge marked the successful conclusion of a years-long effort to obtain funding and then replace this aging, one-lane structure — which was meant only to be a temporary solution when it was installed back in 1986 — while improving safety, traffic flow, and multimodal connections in the city that is its county seat.

Project History & Background

The bridge that carries South Lyon Street over Tonawanda Creek in Batavia was originally constructed in 1910. It underwent a deck replacement in 1957, which the community celebrated through a ribbon-cutting ceremony captured in a photograph that highlights not only the bridge’s value to those who use it, but also its use of a classic Warren steel truss superstructure design for support.

The bridge spans an area of Tonawanda Creek that is flood-prone, and by 1986, the bridge required replacement. It was removed and, as a temporary solution — at least, that was the intent at the time — a Mabey truss was installed on top of the original abutments.

But the temporary replacement structure also only allowed for one lane of vehicular traffic, and it stayed in place longer than is practical for its design. The bridge was first flagged for deterioration in 1994, and it continued to receive flags almost annually after that. Due to its age, structure type, and diminishing load capacity, it was deemed not economically viable for rehabilitation and was closed in 2021. The goals for a bridge replacement included reestablishing two lanes, a dedicated pedestrian crossing, improvement of the intersection geometry at the south end of the project, maintaining hydraulic freeboard in a flood prone area, and, most importantly, constructing a low-maintenance bridge with a minimum 75-year design life.

These last two goals, low maintenance and 75-year design life, drove the design team to use hot-dip galvanizing in lieu of painting or weathering steel. Galvanizing eliminates the expense of and need for periodic painting of the truss. Truss details have historically created areas which collect salts and debris, which diminishes the life of painted surfaces and keeps weathering steel surfaces damp, limiting the steel’s ability to dry and create the necessary protective patina. The team’s engineers also have a 25-year history designing galvanized truss bridges across western NY where the galvanized coatings were tested and are still performing with thicknesses above the originally specified minimums with no history of corrosion or section loss.

Design Approach

To maintain hydraulic freeboard and minimize the depth of the new superstructure while maintaining the road profile, a modified Warren pony truss design was selected for the replacement with an outrigger sidewalk to minimize the depth of the composite concrete and steel floorbeam framing. Retaining a truss design made sense in terms of community identity, since the original and temporary Mabey structures were both truss bridges. An added benefit of this approach was the limited impact to properties on both sides of the creek.

Truss Detailing: Standard rolled shapes were used for all truss elements. Open channels on the bottom chord were placed vertically and used rolled w-shapes for spacers to eliminate flat stay plates because the configuration is self-cleaning and allows for easier galvanizing compared to closed-box shapes. While the NYSDOT Bridge Design Manual suggests using built-up members in typical applications, here the use of the standard shapes allowed cost savings and, due to the relatively short member lengths, helped control tolerances.

Deck: The design uses a deck-floorbeam system without stringers to minimize total structure depth (deck + floor system) due to the limited available hydraulic freeboard. The deck was designed to span longitudinally between floorbeams, and the total deck thickness was reduced to 8.5” rather than the DOT standard 9.5” design.

Sidewalk: The sidewalk was placed on the east side of the bridge on cantilevered steel floor beams. The slab was designed to span between floor beams with welded wire fabric (WWF) reinforcement but was modified during construction to a single layer of two-directional reinforcing.

Foundations: The abutments were designed at the top of bank supported on piles socketed into rock.

Road Realignment: The project site was tucked in a residential pocket across the creek from a commercial district. South Lyon Street required a realignment to improve the geometry of the adjacent intersection with South Main Street, at the southern end of the bridge, and make it safer for users by offering greater sight distances than the original alignment. Approach work was also included for a seamless transition to the relocated intersection, existing roadway, and the sidewalks and pedestrian path running alongside the bridge.

Utilities: Relocation of multiple utilities as well as storm and sanitary sewers had already been accounted for in the design, due to the realignment of South Lyon Street, and the relocations of some overhead utility poles resulted in some changes in curb and sidewalk alignment during construction. A gas line that ran under the creek, however, was in poor condition and could not be repaired or relocated underground, so the utility requested it to be placed on the bridge. The utility supports were designed with outboard cantilever beams bolted to the bridge’s gusset plates to support utility hangers. The cost was born by the utility and did not impact the cost to the municipality.

Project Summary

At a June 2023 ribbon cutting, representatives from Genesee County, the City of Batavia, and the design and construction teams met on the bridge to recreate the 1957 ribbon cutting photo that celebrated the original bridge.

The new steel truss bridge is built to meet current structural standards and provides a service life of 75 years. The structure is hot-dip galvanized to maximize corrosion protection and minimize maintenance costs associated with painting the truss and is considered the key project element to achieve this goal for the County. A single slope concrete barrier protects the truss from salt spray, further reducing the maintenance of the structure. Additionally, the two-lane bridge with a pedestrian walkway has improved traffic flow and safety in the area, and it now reconnects a neighborhood with its surroundings — making the South Lyon Bridge Replacement project a success.