ALTRIOS: Advanced Locomotive Technology and Rail Infrastructure Optimization System


The Advanced Locomotive Technology and Rail Infrastructure Optimization System (ALTRIOS) is the first fully integrated, open-source software to simulate and optimize the rollout of cost-effective locomotive technologies for decarbonization.

ALTRIOS is a simulation and optimization software tool to guide railway operators, locomotive manufacturers, government regulatory agencies, national labs, and universities in deep rail decarbonization. It was built by a multidisciplinary team spanning government, industry, and higher education.

Approach and Uses

ALTRIOS simulates real-world, multi-decade rail network operation in a single unified model, including the following energy-impacting aspects of rail operation:

  • Freight demand-driven train scheduling constrained by technology-specific operating requirements
  • Algorithmically generated target speed traces corresponding to sequences of train departure, meet, and pass events to ensure conflict-free operation
  • Train dynamics, including effects of grade, drag, inertia, rolling resistance, and curvature
  • Locomotive powertrain technologies including diesel electric, battery electric, fuel cell, advanced biofuel, and hybrid fuel technologies
  • Operating condition-based locomotive component efficiencies,
  • Consist power distribution controls to minimize powertrain-specific energy consumption
  • Locomotives’ interactions with fueling and charging infrastructure,
  • External constraints such as railcar size and weight limitations, authorized speeds, and grade and curve resistance
  • Sensitivity studies and optimization to explore the rollout of locomotive decarbonization technologies.

ALTRIOS determines tailored deployment strategies for clean, optimized locomotive technologies and the associated infrastructure needed to achieve decarbonization—all while minimizing operational costs and scheduling impacts.

It is the only tool on the market that combines locomotive and energy storage technology models with robust train dispatching, corridor simulations, and a high-level train planning tool.

ALTRIOS is compatible with Windows, Mac OS, and Linux.

Download ALTRIOS

Install the ALTRIOS Python package directly from PyPI. Download the full source code on GitHub
Explore selected capabilities using the web application ALTRIOS-Lite.

Each marker in this animation shows a mixed-battery-and-diesel-electric consist train simulation, including powertrain performance at 1 Hz; the size of the marker indicates relative battery state of charge. Simulation from Garrett Anderson, Southwest Research Institute

To learn more, read the news stories: 

All Aboard! NREL Releases First Comprehensive, Open-Source Software for Freight Rail Decarbonization

NREL’s Rail Optimization Software Is Putting Freight Electrification on the Fast Track.


ALTRIOS was built with partners in industry and academia, including:

BNSF Railway

Southwest Research Institute

The University of Texas at Austin

University of Illinois Urbana-Champaign.


To learn more about the ALTRIOS simulation framework or to explore related partnership opportunities, contact us at