The Strawberry Mansion Bridge is a steel arch truss bridge over the Shulykill River in Philadelphia, Pennsylvania that was built in 1896 and spans about 1,242 ft.  Arch truss bridges represent an early innovation through the combination of two established and highly successful structural design concepts: arches and trusses.  Arches are a very common structural design element that have celebrated a rich 2,000+ year history due to the high load bearing capabilities resulting from the curvature of the arch.  So long as the curvature does not become extreme, the arch acts to distribute compressive forces throughout the entire structure and divert the material weight to the abutments (where the arch touches down), while virtually eliminating concerns over tensional forces.  The truss is a design element that rose to fame during the Industrial Revolution and which focuses on distributing load through a network of “two force members” (structural components where the load is applied at only two points), often arranged as triangles for added strength & rigidity.  When you combine the arch & truss elements and apply them to the design of a bridge, the result is a relatively light-weight, very rigid bridge with excellent load distribution and lower tensional stresses that injects an elegant and iconic look into the surrounding community.