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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Staying on the Rails with Vehicle-Track Interaction

Track and infrastructure failure is the second leading cause of train derailments in the United States. Many of these derailments and those resulting from equipment failures are attributable to the contact forces that develop at the wheel-rail interface. Vehicle-track interaction (VTI) research investigates these wheel-rail contact forces and their consequences in order to reduce railroad derailments and improve safety.

The U.S. Department of Transportation's Volpe Center has a long history of working with the Federal Railroad Administration (FRA) to develop methods, guidelines, and standards for inspecting, maintaining, and improving track and rail equipment.

The Challenge

Since 2008, there have been approximately 500 derailments per year in the United States caused, in part, by track and infrastructure or equipment problems. Train derailments can have severe, sometimes fatal consequences, result in environmental damage, and cause major delays for freight and passenger trains—sometimes lasting days.

To avoid catastrophic derailments, the railroad industry relies on up-to-date research to better understand the critical characteristics of the complex interaction between rail vehicles and the track structure.

As freight car loads and passenger train speeds increase and travel times improve, researchers particularly want to refine their understanding of the relationship between rail vehicle types and the track characteristics over which they operate.

The Solution

Volpe’s VTI work helps develop consistent standards to ensure that both the track and equipment are adequate to allow trains to operate safely under a wide range of conditions, including passenger and freight operations on different track types and maintenance levels.

Expert engineers create and refine advanced analytical, computational, and testing tools to investigate safety issues than can arise when trains and track interact.

Volpe’s vehicle-track interaction team examines the following:

  • Derailment analyses informed by accident investigations
  • Trackworthiness of rail passenger equipment designs to ensure that the suspension systems are suitable for demanding track conditions and stable at high speed
  • Track geometry and surface irregularities that can lead to derailment
  • Vehicles, wheel designs, and bogies—or chassis—that may be susceptible to particular types of irregularities
  • How excessive loads damage track components and reduce track life
  • Ride safety and quality, particularly related to special track work and higher curving speeds
  • How unconventional, special purpose, or new rolling stock affects track
  • General problems due to passenger and freight cars using the same track
  • How higher loads and higher speeds affect FRA Track Safety Standards and industry standards
  • Development of new track and vehicle inspection protocols to ensure compatibility and identify early indications of incipient failures
  • Specifications for field testing programs involving track and train
  • Computational techniques for non-recurring track and train problems

The Impact

Volpe’s research helps keep the nation’s rail system safe and operating efficiently. Detailed track assessments and design improvements can also help railway operators evaluate investment options to increase capacity and improve trip times on existing lines without sacrificing safety.

As an example, Volpe engineers have developed and are evaluating procedures to qualify new equipment, including assessing the performance of operating at higher curving speeds (i.e., high-cant deficiency) and over complicated track layouts near major stations and terminals. Some of this equipment has been designed for high-speed operations and may be challenged by the types of track irregularities seen in service.

Furthermore, Volpe’s researchers have developed state-of-the-art inspection and testing tools and assessment protocols that are used by Amtrak, state authorities, and freight railways to assure that the track can meet the physical demands of high-speed service or increased freight traffic.

Train coming down the track


Federal Railroad Administration