• The bridge is of a special concrete-type, i.e., filled-spandrel arch consisting of a single barrel shell/arch rib and two side spandrel walls supported on a series of reinforced concrete counterforts. The arch rib extends continuously (over massive concrete piers) for a total of seven equal spans of 95 feet each (clear span-length). The bridge has three traffic lanes of 12 feet each, in addition to two side walks of approximately 6 feet width for each. These constitute the two main live-load carrying capacity of the bridge superstructure, hence considered here as a basis for the bridge rating analysis.
• The railing and exterior concrete on the sidewalks exhibit significant deterioration and spalling. In addition, there was noticeable deterioration in two typical locations:
  • Concrete covers on the outside faces of the spandrel walls at several positions, especially near the center span.
  • Longitudinal type (traffic direction) cracks of extensive length in many areas on the bottom (soffit) side of the arch rib.

Rating was performed on the two main superstructure components: (i) Arch rib, and (ii) Spandrel walls. To this end the finite element computer program SAP90/2000 was utilized.

In view of the results, it was determined that the bridge, despite its “old” age, has adequate reserve of strength (i.e., rating factors of nearly one or more for all different cases considered) for a number of more years to come.
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