IN-42 Mill Creek Bridge

Information and Findings From DHPA Historic Bridge Survey

Statement of Significance

The ISHC did not long keep on its system the covered timber trusses it inherited from the counties. The Bell Bridge, an 84-ft. span with a 16-ft. roadway built in 1886, was no exception. In June 1940, the state contracted with George R. Harvey of Danville, Indiana, for $67,632.17 to build a replacement structure of its own design. Harvey completed construction by the late spring of 1941. The ISHC used revised versions of the third-generation standard plan #475A for a 175-ft., riveted, Parker through-truss span with a 24-ft. roadway for this and a dozen other structures. Truss depth varied from 21 ft. 6 in. at the portal to 31 ft. 6 in. at midspan. Each truss carried ten 17-ft. 6-in. panels. Every top chord member is differently sloped; none is parallel with the lower chord; and all were fabricated from a pair of 15-in. channels (@40# for the endposts, fourth, and fifth panels, and @33.3# for the second and third). Two pairs of angles--all of the same size (6"x4"Ls)--riveted together with battens and buttressed in all but the two most outer panels with plates provide the lower chord's members. The truss webbing is also substantial. The verticals or posts, except for the hip one, consist of a pair of laced 10-in. channels (@15.3#). A 10-in. I (@39#) supplied the hip vertical. To protect the quite-tall trusses against wind and vehicle-induced stress, the verticals are buttressed with substantial latticed struts and heavy upper sway framing above the 15 ft. of roadway clearance. The portals used latticed sections, too. The diagonals combined a pair of angles with battens into heavier members in the outer panels (6"x4"Ls) than in the central ones (3.5"x3"Ls). A pair of angles (3"x3"Ls) and battens provide counters in the two most central panels. The ISHC used 33-in. I floor-beams (@141#) riveted to the verticals above the lower chord. Eight rows of heavy rolled I stringers (16"@36#) are attached to the floor-beams' sides. Together, the floor-beams and the stringers carry the concrete deck with 15 feet of vertical clearance. A pair of angles supplies each lower sway- bracing member. Post-and-channel rails line the inner sides of the trusses, and coped concrete rails with bush-hammered panels mark the approaches. The superstructure sits upon state-designed concrete abutments. This bridge exemplifies a much-used, revised third-generation ISHC standard plan. The trusses retain their original members, original guard rails, and coped concrete approach rails with bush- hammered panels. Only the concrete deck and a few stringers have been replaced. References Indiana Department of Highways, Inventory of Bridges on State Highway System of Indiana (Indianapolis, 1989). Indiana State Highway - Structure #42-F 67-3172 Contract #1979 Superstructure Standard # 475A

Bridge Considered Historic By Survey: Yes