The Kittanning Street Bridge in the city will be replaced in 2013.

Representatives with the state Department of Transportation on Wednesday evening unveiled plans for the project at a forum at Butler’s city building.

They answered questions about the project, which will replace the two-span, two-lane bridge carrying Kittanning Street over the Connoquenessing Creek and into Butler Township.

The 80-year-old bridge will have at least one lane open during construction.

Two big changes will take place with the construction, the first being demolition of the three-story apartment building at 225 Kittanning St.

The building will be razed so bridge approaches and the curve leading up Kittanning Street toward Mitchell Hill Road can be widened as well as to improve sight lines to the bridge coming down the hill.

The second major change is the exclusion of sidewalks on the new bridge.

Although the new bridge will be the same width as the current one, about 38 feet, the sidewalks on the current bridge will not be reinstalled. Instead, an eight-foot shoulder will flank each side of the road.

Replacement of the 108-foot bridge is in the preliminary design stage and is expected to cost about $3.5 million.