NDE System for Determining Wood Guardrail Post Integrity

Abstract

Wood guardrail posts degrade over time and a nondestructive evaluation (NDE) inspection system is needed to determine the condition of the nearly 2 million posts along our highways to prioritize future investments in maintenance. A robust, cost-effective stress wave technique was developed that addressed deficiencies in current equipment with regard to accuracy, ease of use and worker safety; efficient ways to acquire/store/transmit data; along with heuristics to interpret data and guide decision-making on guardrail maintenance and replacement. The stress wave timing (SWT) technique was judged most promising, and a prototype device was developed with an industrial partner. The system includes wireless communication features and can be operated with a smart phone app. The system was validated with over 200 guardrail posts that were removed from service and tested at the WSU campus. Field-testing of the device occurred on December 18, 2014 with WSDOT personnel in a western Washington location. Internal conditions of the posts were accurately detected in 86% of the specimens. The device also successfully detected the internal condition of all posts inspected during a field test. An inspection procedure was recommended for implementation using SWT in conjunction with drilling of posts that are suspected to have decay. Field inspection protocol, training materials and final report were developed and presented to WSDOT staff in Olympia on June 1, 2015. A final project report was submitted to WSDOT on June 29, 2015.