There are more than 600,000 bridges in the United States alone, and 1 in 4 are considered structurally deficient.
Fatigue, cracking, corrosive degradation due to both age and weather-related faults can put bridges under undue stress. Further, increasing traffic, larger loads from trucks and transport vehicles cause additional load strain and can contribute to unpredictable bridge failures. Bridge structure, footings, bridge supports and cables are difficult to inspect frequently and on a regular basis. Shutting down a bridge for this level of inspections is often not an option either due to their critical need for transportation.
Jewell Instruments’ inertial sensors are being used more and more worldwide to monitor a wide variety:
- Bridge deflection
- Performance after construction
- Bridge footings, and ground movement
Jewell Instruments’ inertial sensors can be mounted across the bridge to measure movement, bridge deflection twist and rolling, buckling or distortions. Our tilt sensors can be mounted on footings either above or below ground or underwater to measure ground movements due to compaction grouting of the ground beneath the bridge footings, bridge movement, or seismic activity. Even if a new bridge is designed to withstand seismic activity, Jewell Sensors can be utilized on beams or other locations on the bridge to monitor angle to determine when the seismic qualified support pads need to be replaced. Bridges with box girders inside the bridge have proven to be an effective solution since they provide an area protected from weather extremes, and Jewell Instruments Geotechnical tiltmeters can provide high quality, low-noise and extremely accurate data.
Pier monitoring
For several decades, Jewell has been developing high-precision tiltmeters for bridge monitoring, including steel truss, post-tensioned segmental box girder, and composite-type structures. Clients have used these systems for monitoring of bridge construction, long-term performance evaluation, and as damage/maintenance assessment tools. Jewell high-precision sensors offer continuous data coverage to provide contractors, engineers, and owners with immediate feedback on structural performance and conditions. Jewell tiltmeters continuously monitor the piers of the Golden Gate Bridge with a stainless steel version of our A711 series to detect any movement caused by earthquakes, settlement or scour. Through a PC in the bridge office the bridge district remotely collects and reviews the data, without sending someone out to the bridge. For underwater measurements, we also offer waterproof tiltmeters such as the shallow-water 820 series (rated to 200 meters) and deep-water 802 series (rated to +2500 meters) for advanced protection.
Bridge deflection and Health monitoring
During construction, Jewell tiltmeters have been used to plumb the pivot shafts to true vertical. They then measured and maintained balance during casting of the main and tail spans of each leaf. If a ship collides with protective piling, the tiltmeters can help determine that no permanent damage to the bridge has occurred. Today our tiltmeters maintain pivot shaft alignment and monitor foundation integrity in these seismically active areas.
Our high precision tiltmeters such as the 801 Tuff-Tilt series have been used on continuous self-anchored suspension bridge and installed on the main towers to monitor long-term tilt. Jewell tiltmeters were also installed to monitor deflection of long bridge arches.
Bridge Truss Distortion Monitoring
As part of the bridge widening project over the Mississippi River in New Orleans, two 528ft long, 2700 ton trusses were built on shore, and transported to the bridge site by barge. Jewell C801 “Tuff-tilt” tilt meters were used to monitor each truss for distortion and bucking as they were lifted and secured into place.
