Field load testing of open-deck timber trestle railroad bridges

This paper is an overview of recent load testing performed on timber trestle railroad bridges in the United States. Many timber trestle railroad bridges have been in service for 40-100 years. Imminent code changes for increased load requirements led to the railroad industry's interest in field test programs for in-place timber trestle bridges. Loads were applied by known axle weights of a test train positioned on bridge and use of a load axle of a "track loading vehicle". Rolling train load tests were conducted, too. Material properties were determined in-place by use of ultrasonic equipment. Field performance and load sharing are investigated. Results of various analytical models are examined in comparison with field data.