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  Spring Field Review Site 11
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Spring Field Review Site 11

Description: R-2248BC & R-2248D - MECKLENBURG COUNTY

Location: Bridges over Long Creek and several grade separations at interchange.

Item(s) of Interest: Span arrangement and bridge skew issues. Also, constructability issues with the deck and shoulder superelevations as designed.

Observations and Points of Discussion:

  • One of the bents was designed for a post-tensioned integral bent cap. The design required 4 ksi. concrete strength prior to tensioning and 5 ksi. for the final strength. At 21 days the strength was 3.96 ksi. The contractor was waiting to see if 4 ksi would be achieved.
  • If design strength is not achieved, additional measures could include:
    • Hiring a consultant to perform a cap rating for standard vehicles and super loads. This would be very helpful to the Bridge Maintenance Unit.
      Utilizing a lightweight concrete deck.
  • The Department should avoid utilizing post-tensioned integral bents, unless absolutely necessary. When necessary, ensure the following:
    • Adherence to all restrictions before the allowing their use.
      Better consultant coordination during the design phase.
      The girders control the design and not the bent cap.
  • Hammerhead bents on the same project did not look uniform, due to designs by different consultants.
    • Several planned large loop projects planned for the future will raise similar issues.
      Need more uniformity -- ensure better consultant coordination during the design phase.
  • The Construction Unit gave a detailed explanation of the complexities of screeding operations for the following conditions:
    • Heavy skews.
      Transitioning superelevation on the bridge.
      Two bridges merging into one bridge.
  • The Roadway Unit stated that they try to avoid the conditions stated above whenever possible. However, it is not always possible, especially on big urban interchanges.


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