“Will the rail be safe to travel on?” The answer is a definite, “Yes, it absolutely will be.”
Local engineer Dennis Mitsuna-
ga recently raised this question in a full-page advertisement. The Honolulu Authority for Rapid Transportation (HART) appreciates the input and concern, but feels he did not have the benefit of all the details regarding this issue, and may have unwittingly and unnecessarily caused public concern. In this instance, it is important to offer clarity on the issues raised and set the record straight.
The steel tendons, which are cables that support each section of the elevated guideway between any two columns, are the main load-carrying structural elements. The typical span has six tendons that run the length of the span in ducts. Tendons are installed, pulled tight, anchored at the ends, and a follow-up crew pumps grout into the ducts to fully envelop the tendons. The grout is thick fluid cement that sets up like concrete and protects the tendons from corrosion.
The railings at Ala Moana Center that failed, which were mentioned in the ad, were exposed to the elements and did not have this same protection.
Three of the 1,586 tendons in the first segment fractured after the tendons were anchored but before they were grouted. Those were immediately noticed by inspectors from the contractor and HART. They were quickly replaced with brand new, defect-free tendons.
Both the contractor and HART hired independent, nationally-recognized forensic engineering firms specializing in this type of work, who determined that water in the ducts caused the three previously mentioned tendons to corrode and fracture. The contractor immediately took measures to prevent water from reaching the tendons and initiated a course of inspection to prevent corrosion in the tendons that are to be installed in the future.
To address the tendons that had already been grouted, the contractor searched its records to identify tendons with water infiltration. In addition, crews chipped away grout at the anchors of 57 tendons. Nine additional tendons were identified with either corrosion or grout issues and they, too, were also fully replaced.
HART is requiring still more to be done, so plans are underway to inspect 100 percent of the tendons to assure the integrity of each span and the safety of the overall system. In addition, once the rail system is completed, the guideway structure will be inspected every two years in accordance with the National Bridge Inspection Standards of the U.S. Department of Transportation, a requirement for all bridges across the country.
Construction issues are inevitable for a large, complex project such as Honolulu’s rail system. It is HART’s responsibility to the people of Honolulu to monitor and manage the construction, identify and resolve issues, and hold the contractor to the high standards set for this particular project.
This is one of the largest rail infrastructure projects in the country, and HART is proud of the world-class expertise that is already involved in making rail a safe, convenient and reliable reality for Hawaii.
Charles S. Carnaggio is project director for the Honolulu Authority for Rapid Transportation.
