Skew Detection System Replacement on Vertical Lift Bridges

For a tower drive vertical lift bridge, failure to maintain level operation over its length or width is known as span longitudinal or transverse skew. When occurring, this can lead to jamming of the movable span in its guides and, without adequate protection, can lead to a catastrophic bridge failure. Vertical lift tower drive skew indication and monitoring was historically satisfied with the use of a differential selsyn. However, this legacy technology is nearly obsolete. This study included a review of alternatives for skew control, monitoring, and indication for tower drive vertical lift bridges based on effective management of skew and minimizing advanced electronic equipment. Based on this review, the preferred system for skew control combines the use of direct skew measurement with an inclinometer for skew monitoring and trip indication, and indirect measurement of skew using encoders for controlling skew during operation. To minimize maintenance, mean-time-to-repair, and to limit dependency on Programmable Logic Controller (PLC) systems, control integration should include the use of SMART relays that contains self-diagnostics and may easily be replaced in the event of an issue.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Figures; Photos; References; Tables;
  • Pagination: 44p

Subject/Index Terms

Filing Info

  • Accession Number: 01835542
  • Record Type: Publication
  • Report/Paper Numbers: FHWA/LA.17/643, LTRC Project Number: 20-2ST, SIO Number: DOTLT1000343
  • Files: TRIS, ATRI, USDOT, STATEDOT
  • Created Date: Feb 7 2022 5:26PM