Recognizing CTLGroup's innovative effort in defining cable-stayed bridge inspection testing and rehabilitation methods, the Louisiana Department of Transportation and Development (LaDOTD) selected CTLGroup to prepare final design plans for the first-ever, complete stay-cable replacement project in North America. The rehabilitation plan for the 26 year old structure, provides the Luling Bridge, a landmark on the Interstate Highway system that carries I-310 across the Mississippi River between Luling and Destrehan, Lousiana, a basis for achieving an extended service life. The bridge preservation action was necessary due to the advanced state of deterioration of the stay cable array, which threatened the bridge.
The 1,221-ft long span, opened to traffic in 1983, was impaired by deteriorating stay cables from the start. Stay cables support the bridge superstructure and are vital, fracture-critical elements. Bridge cables like these are a challenge to inspect, but must be monitored and maintained in sound and durable condition to assure public safety and attain intended bridge service life. Several previous attempts at repair of the degrading Hale Boggs cables, which suffered the consequences of defective corrosion protection systems, were ineffective.
In 2002, following successful CTLGroup development of NDT-based inspection systems for cable-stayed bridges, and widespread recognition of the firm's expertise, LaDOTD engaged the firm to authoritatively assess condition and vulnerabilities of the bridge cables. The Department wished to make a confident and cost-effective rehabilitation decision. Upon completion of CTLGroup inspection, condition analysis and life cycle cost study of repair alternatives in 2006, LaDOTD chose to proceed with the cable replacement option. The U.S. Federal Highway Administration provided cooperative assistance and funding for the project.
A complete cable replacement plan was designed by the CTLGroup team. The design goals included, among other things, minimization of traffic backups during the challenging repairs on a highway which serves as a primary Louisiana hurricane evacuation route. A construction plan was developed by the design team, which allows repairs to be made adopting just a single lane closure for the 82-ft wide structure. The $36 million construction project, now in progress, is scheduled to be completed in 2010.
CTLGroup is renowned for its innovative bridge structural evaluation and repair solutions. The firm has inspected and helped owners and consultants evaluate more than 45 major river crossings and historic and landmark bridges including cable-stayed, post-tensioned segmental, suspension and arch structures. Since 1997, CTLGroup has evaluated more than 25% of the stay-cable bridges in the U.S. The Luling Bridge is a notable example of the firm's capabilities and bridge engineering leadership, rolled into one successful achievement.