The existing Viaduct is over 70 years old and has many documented structural deficiencies. Additionally, US 77 is the primary route through downtown Waxahachie, but does not adequately serve the area's traffic needs.

Structural Deficiencies

Bridge surveys of the US 77 Viaduct were conducted in January of 1998, January and July of 2002 and July of 2004. Chloride contamination from deicing salts has led to corrosion within the superstructure. Each survey determined that it would not be feasible to widen or reconstruct the superstructure of the bridge.

The substructure is still in good condition, however, and could be rehabilitated for use with a new superstructure that meets certain design conditions.

Traffic Volumes

Traffic volumes for existing US 77 (Elm Street) are projected to be 17,000 vehicles per day (vpd) for the year 2010 and 23,800 vpd for the year 2030. The use of the couplet option would lower the volume of traffic on Elm Street to 9,300 vpd in 2010 and 13,000 vpd in 2030. The projected traffic volumes for Monroe Street are 9,400 vpd in 2010 and 13,200 vpd in 2030.

Level of Service

A Level of Service (LOS) analysis was conducted in June of 2005 and January of 2006 by TxDOT consultants. Each analysis measured the year 2010 and 2030 traffic volumes for US 77 between FM 66 and Monroe Street.

  • First Analysis: Examined intersection LOS (based on turning movements at specific intersections) for the existing roadway versus a couplet option.
  • Second Analysis: Compared the LOS for the existing facility (encompassing the intersections and the roadway) and four alternatives for an improved US 77 facility, including a couplet option.
  • Conclusion: Year 2010 traffic volumes allowed for acceptable intersections (LOS D) in 2010 but LOS F for the existing facility in 2010. In the year 2030, both the intersections and the roadway would operate at a LOS F. The couplet option studied in both analyses produced an acceptable LOS D for the year 2030 and beyond.

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