Identification of Test Methods for Determining Wood Guardrail Post Integrity

Wood guardrail posts are subject to decay and deterioration, yet most Departments of Transportation (DOTs) have minimal or no inspection procedures in place for wood guardrail posts. The objective of this study was to identify nondestructive testing technologies to assess the condition of wood guardrail posts for internal decay. The stress wave timing (SWT) technique was judged most promising, and a prototype device was developed with an industrial partner. The prototype SWT device was validated using wood guardrail posts removed from service. 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 identified as suspected decay.