6th Street Viaduct

The Sixth Street Viaduct (also known as the Sixth Street Bridge) is a 3,500 ft. bridge in Los Angeles that connects the historic Boyle Heights on the east side with the Downtown Arts District on the west.

The 3,500 ft. viaduct crosses over 16 lanes of highway, 18 sets of railroad tracks, the LA river, parks, buildings, and side streets and includes 10 network arch spans, with a total of 388 hangers supporting the bridge deck.

The bridge deck was initially supported by formwork. After the arches were constructed and the hangers were installed, the formwork was removed. The deck is now suspended from 10 pairs of arches and 388 hangers.

MONITORING

Vibrating wire Strain Gauges were installed on the hangers to monitor the transfer of load to the arches Strain measurements were also used to monitor the final balancing of tension in the hangers.

Special clamps were designed by Geo-Instruments to attach the gauges to the 2.75-inch diameter hanger cables. Offsite calibration tests were performed to characterise the response of the strain gauges to the tensioning of the cables.

PACKAGING EFFICIENCY
Geosense worked closely with Geo-Instruments to plan for the large number of sensors (408) and cable lengths (29,120 ft.) used on the project.

Each VWS-2100 Strain Gauge was fitted with individual cable lengths and uniquely marked, packaged and labelled for each span.

This improved the efficiency of the installation process and eliminated any confusion over sensor location.

The actual load transfers were done early in the morning when the temperature of all elements was in equilibrium.