Wisconsin

Network-Level and Aerial Bridge Deck Evaluations in Wisconsin

Over the past 15 years, Infrasense has performed Level 0, 1, 2, or 3 condition surveys on over 3,600 Wisconsin bridge decks representing approximately 36 million square feet. These surveys were performed using some combination of vehicle-based infrared thermography (IR), ground penetrating radar (GPR), and aerial IR. In 2021, Infrasense evaluated 749 decks using aerial IR testing, representing nearly 5% of the total number of bridges across the state of Wisconsin. In recognizing the value in this highly economical network-level information, Wisconsin DOT has recently implemented a policy to scan all bridge decks greater than 15-years old on a 5-year cycle!

The most basic level of bridge deck condition evaluation performed by Infrasense is Level 0. This relatively new approach quickly and efficiently provides an estimated level of delamination at a network level. In 2017, Infrasense participated in a pilot study to determine the feasibility of performing infrared surveys using a fixed-wing aircraft by comparing aerial and vehicle-based data for four bridges in La Crosse. The results of that comparison were positive, and in 2018 Wisconsin selected 120 bridge decks to be surveyed and analyzed with the Level 0 approach.

For vehicle-based bridge deck testing, Level 1 evaluations are carried out for each deck according to ASTM D4788-03 (IR) and D6087-08 (GPR) to determine deterioration quantities and to identify decks with significant deterioration quantities. Data collection is performed at normal driving speed with minimal disruption to traffic. Some decks are selected for a more detailed Level 2 evaluation, which includes the preparation of plan-view maps showing delaminated and deteriorated deck areas.