Bridge Inspection & Condition Assessment – Inspections

The dominant practices used by state departments of transportation (DOTs) in the evaluation of bridge decks have been visual inspection and simple nondestructive methods such as chain dragging and hammer sounding.

The traditional methods are limited greatly by engineers experience, visual and acoustic hearing abilities. The resulting findings are very open to human interpretation and therefore inconsistent and problematic. As advancements in technology have been adapted to metal bridges and structures through advanced metallurgy testing methods it is now considered the norm to utilize non-destructive imaging techniques and testing methods.

BCAR System (Bridge Condition Assessment Radar)

High-speed NDT technologies such as ground penetrating radar, infrared thermography, and pulse echo scanning have been increasingly used in recent years for bridge deck condition assessment. However, up to now these technologies have not been widely adapted or accepted for three main reasons: Highway agencies are not fully aware of the capabilities and limitations of these methods or how they can best be used. Some agencies have had less-than-positive experiences with NDT techniques, perhaps because of unrealistic expectations and the improper use of these technologies. Contractors not skilled or qualified in the advanced interpretation of electromagnetic methods, advanced wave theory and engineering design. Interpretation of data should only be performed by a Senior Engineering Geophysicist.

BCAR (Bridge Condition Assessment Radar) is a pulse GPR system specifically designed for bridge inspections & condition assessment. This high frequency array is lightweight and maneuverable yet provides high quality, densely sampled data. Denser sampling produces higher quality tomography and 3D images which considerably assist the interpretation of data. The system is composed of an array of eight horizontally polarized 2GHz channels with 10cm spacing, mounted on a lightweight and highly maneuverable trolley and powered by a large, 24Ah 12V battery. By processing the complete collected data set with automatic estimation algorithms, bridge deck conditions can be assessed by cross-correlating all the information extracted, such as depth of the rebar layer, concrete slab thickness, power reflected by the rebars, and estimation of moisture presence by propagation velocity estimation.