Use of Wind Power Maps to Establish Fatigue Design Criteria for Traffic Signal and High-Mast Structures

Recent design requirements for traffic signal and sign structures incorporated fatigue load criteria related to wind that are producing significant increases in size and cost. The Fourth Edition of the AASHTO Luminaire and Traffic Signal Specification (2002 with interims) is a significant change to past practice and often results in much larger and more costly structures. The revised specification applies conservative principles (envelope wind demands and infinite fatigue life) for design at increased cost even for those regions not adversely affected by wind-induced fatigue. The states that do not have steady, sustained winds and have not experienced significant fatigue failures have concerns with the larger and more costly structures. A rationale basis for lowering the fatigue design loads may be appropriate. This study compares fatigue failures with respect to wind power (expressed as a function of average wind velocity). Inspection reports for approximate 2500 cantilevered traffic structures and 700 high-mast luminaires were collected and analyzed for suspected fatigue cracking. Each structure was located spatially and the associated wind power classification for that location was noted. (Wind power classifications are used to site wind generators.) This paper is limited to traffic signal structures. The inspected structures were classified as cracked or non-cracked and then categorized by their wind power classification and ambient average wind velocity. The probability of a structure having fatigue cracks increases with greater wind power classifications. Structure orientation, pole diameter, mast-arm length, in-service age, along with other details were also studied for their roles in in-service fatigue performance. Structures in low wind power classes have a lower probability of having fatigue developing cracks. The converse is true.


  • English

Media Info

  • Media Type: Digital/other
  • Features: Appendices; Figures; References; Tables;
  • Pagination: 104p

Subject/Index Terms

Filing Info

  • Accession Number: 01123421
  • Record Type: Publication
  • Report/Paper Numbers: MPC Report No. 08-207
  • Files: UTC, TRIS, USDOT
  • Created Date: Mar 13 2009 9:40AM