Rail Fastener Qualification Program for Major U.S. Transit Agency


CTLGroup was contracted to conduct a multi-project rail fastener qualification and production testing program for a major U.S. transit agency. The program started with qualification testing of direct fixation fasteners (DFF), resilient block fasteners, and special track work fasteners. Testing was conducted in accordance with the transit agency’s qualification test procedures.

The following static tests were performed on the different types of fasteners:

• Vertical load Test
• Vertical Uplift Test
• Lateral Load Test
• Longitudinal Restraint Test
• Dynamic to Static Stiffness Test
• Electrical Resistance (Dry and Wet)
• Electrical Impedance
• High Potential

The following dynamic / conditioning tests were performed on the various types of fasteners:

• Longitudinal Push-Pull Test to 2,000,000 cycles
• Vertical and Lateral Repeated Load Test to 2,000,000 cycles
• Heat Aging

Loads were applied using servo hydraulic actuators ranging from 10 kips to 75 kips. Load and deflection data were measured using strain gauged load cells and linear variable differential transformers (LVDT), respectively. All measurements were collected using a digital data acquisition system along with a custom program to display and write the data to files for analysis.
The static test were performed first followed by the dynamic / conditioning tests. Once the dynamic / conditional tests were complete, the static tests were once again performed. The data collected during pre-static tests was compared to the data collected during post-static tests to see what effect, if any, the dynamic / conditioning tests had on the performance of the fastener.
The qualification testing was requested by the transit agency to verify that the products that were purchased meet the design requirements that were specified in the project contract.
Once the qualification testing was performed, the production testing was started. Production testing was performed on a sample per lot of fasteners produced for the transit project. This is done as a check to verify the consistency of the product purchased by the transit agency.

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