An ongoing challenge in the USA is that our transportation infrastructure is aging, as attested to by the increasing traffic and the resulting load limits being placed on bridges. In the present technological world, bridge monitoring does not have to rely on periodic human inspections, but could rely instead on electronically monitoring a bridge’s health, so it can be maintained and repaired well before any structural integrity problem could develop.
Civil engineers who have the responsibility of keeping the infrastructure sound are becoming aware of sensor products available that could aid them in evaluating infrastructure condition. In a relatively short period of time, the cost of instrumenting a typical bridge can offset the cost of periodically sending an experienced inspection crew to that bridge. Alliance Sensors Group's LV-45 series linear position sensors are an important part of Metrom Rail LLC's SafeStructure™ system that can monitor important structural elements of bridges and transmit data to a remote information collection system in real time. These sensors are rated IEC IP67, and have built-in electronics that can operate over the wide temperature ranges found in the blustery winters of the northern reaches of the US, the dry, hot summers of the southwest, and the hot and humid conditions of the southeast.
In the picture above, two position sensors are attached to the bridge and its supporting pier with rod-eye swivel ends to allow them to measure movement of the bridge over all three axes relative to the pier over time and ambient temperature. The LV-45 sensor is offered with either aluminum or stainless steel housings, a variety of mounting hardware, and cable or connector electrical terminations. These sensors give an analog output of either a high-level DC voltage or a 4-20 mA current loop, either of which can easily connect to any data acquisition system for continuous monitoring and/or data transmission over a remotely accessible wireless network.