*Article* **Comparison of Non-Destructive Techniques for Technological Bridge Deflection Testing**

**Jacek Kwiatkowski 1, Wojciech Anigacz <sup>2</sup> and Damian Beben 2,\***


Received: 18 March 2020; Accepted: 15 April 2020; Published: 18 April 2020

**Abstract:** This paper presents a comparison and assessment of usefulness of various measuring techniques (terrestrial laser scanning (TLS), tachymetry, photogrammetry) applied to establish the behavior of a suspension bridge under different load scenarios. The applied techniques were examined on the bridge with a 165 m span. The tested structure works as the technological bridge for a belt conveyor linking a lime mine and cement plant. The testing range consisted of conducting the non-contact measuring of the bridge and cable displacements under dynamic loads (during the belt conveyor movement—normal service loads) and static loads (while stopped). Tachymetric surveys were carried out using a precise total station (to obtain the reference data). A Canon 750D digital camera was applied in the photogrammetry technique. FARO Focus 3D and Trimble TX8 scanners were employed for the TLS measuring. The obtained results are especially important for bridge inspectors and managers who can use the non-contact measurements of serviced structures.

**Keywords:** laser scanning; photogrammetry; tachymetry; bridge deflection; non-contact measurement
