RESEARCH
This article is reprinted with permission from the U . S . Department of Transportation ( DOT ). The article appeared in the October 2021 issue of UTC Spotlight , which highlights work being conducted in University Technology Centers supported by the DOT .
An Energy-Harvesting Railroad Tie for Improving Track Condition Monitoring and Safety
Researchers at the Railway Technologies Laboratory ( RTL ) of the Center for Vehicle Systems and Safety ( CVeSS ) at Virginia Tech have designed and developed an energy harvesting railroad tie , shown in Figure 1 , to power trackside electronics and sensors for improving track condition monitoring and safety . As a member of the Rail Transportation Engineering and Advance Maintenance ( RailTEAM ) consortium led by the University of Nevada Las Vegas ( UNLV ), RTL is funded by the U . S . Department of Transportation University Transportation Center program . RTL explores technologies that advance railroad sciences and enable the U . S . rail industry to become more efficient and globally competitive .
The shortage of electrical power along railroad tracks significantly limits the railroads ’ ability to apply intelligent solutions for improving rail safety and connectivity . Much advanced wayside electrical equipment desired by the U . S . railroads cannot be employed readily on tracks due to the absence of electrical power . For example , some railroads use drones as a preferred means of physical inspection of track conditions , but the average maximum battery life for most commercial drones is only 22 to 27 minutes , significantly limit their operational range and length of flight . Drone use is enabled to reduce interruptions to train traffic flow and safety risks associated with having personnel present on revenue service tracks . Lack of electricity along tracks is a limiting factor in broad implementation of drones for railroad applications . Therefore , finding a reliable way to efficiently power the advanced trackside electrical equipment and autonomously / wirelessly charge drones is necessary for achieving the goal of improving track safety and condition monitoring .
Figure 2 demonstrates the working principle and motion transmission of the embedded electromagnetic energy harvester . The red arrows represent the direction of movement when energy is harvested , while the green arrows shows the return to undeflected position . Under the force of a passing wheel , the tie moves downward with a small amplitude and compresses the harvester , causing the rotation of the ball screw shaft and the bevel gear pair , which in turn rotates the generator at high speeds . The direction of rotation for each component is shown by red arrows in Figure 2a .
Figure 1 . ( a ) Design overview of energy harvesting tie ; ( b ) various railway applications can be powered by energy harvesting ties to improve rail safety and connectivity .
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Energy Conversion |
Railway Application |
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Track Vibration Energy |
Wayside Lubricant System |
University of Nevada , Las Vegas |
Traditional Railroad Tie |
Energy Harvesting Tie |
Traditional Railroad Tie |
Energy Harvesting Tie
Electrical Energy
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Hot Box / Bearing Detector
Track Circuit Monitoring
Inspection Drone
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18 VIRGINIA TECH MECHANICAL ENGINEERING • ANNUAL REPORT 2020-2021