A Railroad Perspective on Bridge Measurement and Monitoring Systems

Railroads have a long history of bridge measurement and monitoring — typically for purposes of structure protection or load capacity rating. In recent years, a number of vendors started offering structural health monitoring (SHM) systems, which take numerous measurements and market bridge life extension. This paper offers an overview of the fundamentals of railroad bridge monitoring and measurements, as well as examples and suggestions for appropriate use of each. Key issues discussed include: Targeted applications are most effective for any railroad bridge monitoring, measurement, and SHM efforts. Several bridge monitoring or protection systems are already in regular use by most railroads, although they might not fit the current marketing definition of SHM systems. One-time, short-term bridge measurements can be beneficial; particularly in conjunction with load capacity rating. Periodic monitoring can be beneficial and often is more appropriate than full-time SHM. Railroads generally need actionable information rather than the vast quantities of data potentially available from SHM systems. Any new systems should be highly reliable to keep false alerts, unplanned maintenance, and resulting service interruptions to a minimum. SHM systems can be beneficial in monitoring existing, older bridges. SHM systems need to be as maintenance-free as possible, or the cost of maintenance and the track time needed to perform it will offset potential benefits.