February 9th, 2012
DEFLECTIONPreserve Infrastructure, by Catherine Higgins.
A falling weight deflectometer is a non-destructive method for testing the load capacity of pavement.
A FWD is a machine with sensors that measures pavement deflection when a raised weight is dropped. The force of the dropped weight is transmitted to the pavement by a load plate.
The FWD simulates traffic and from the data gathered from the tests, engineers “can tell a lot about the pavement characteristics,” such as pavement thickness and load transfer properties according to Gary Kuhl, UDOT’s Statewide Pavement Management Engineer.
Pavement needs to be appropriately stiff and flexible to hold up to traffic loads – stiff enough to be durable and flexible to rebound from traffic. The FWD measures pavement deflection at the drop point and extending five feet away. Layer thickness, pavement temperature, and deflection data are collected, and remaining life can be calculated when traffic volumes and weights are included.
UDOT has an FWD that can be used to collect data on project level roadways. The data is very useful for pavement maintenance and design engineers. While many engineers at UDOT are familiar with FWD and what it does, not all are familiar with how to make full use of the data.
A training to give pavement and maintenance engineers information about how the FDW can help with pavement design is planned for February 2 7 in Region Two. Engineers from across the state will attend to learn more about the FWD and how to fully exploit data for pavement design.
For more about FWD testing, see this article on the Pavement Interactive website.