On April 15, 1982, a portion of Ramp C of the Riley Road Interchange in East Chicago, Indiana collapsed during construction and resulted in the death of 13 workers. The Occupational Safety and Health Administration requested the assistance of the National Bureau of Standards (NBS) to carry out an investigation of the technical reason for the accident.
On April 17, a team of structural engineers from NBS arrived at the accident site and initiated its study. In addition to an extensive field investigation, the team performed physical tests to characterize the behavior of various critical structural elements. In parallel with the testing, a detailed structural analysis was performed on the partially completed structure. The calculated forces in key components were compared with their expected strengths, from which the most likely cause of the failure was determined.
It was concluded that the following deficiencies contributed directly to the collapse:
- the omission of specified wedges between stringers and crossbeams;
- the concrete pads had an inadequate margin of safety to resist the expected construction loads;
- the tops of the shoring towers were not adequately stabilized against longitudinal movement; and
- the weld quality in the U-heads was poor.
Had and one of these deficiencies not existed, it is unlikely that the collapse would have occurred.
Details of the investigation and conclusions are available in the NIST report, "Investigation of Construction Failure of the Riley Road Interchange Ramp, East Chicago, Indiana (NBSIR 82-2583)."