Advanced science.  Applied technology.


SwRI helps create open-source software to assist rail industry decarbonization efforts

August 7, 2023 — Southwest Research Institute is helping the freight rail industry assess potential pathways to decarbonization with a new open-source modeling and simulation software known as ALTRIOS. ALTRIOS, the Advanced Locomotive Technology and Rail Infrastructure Optimization System, can simulate the real-world impacts and expenses related to adopting alternative energy locomotive technologies and expanding associated infrastructure.

Now publicly available for download, ALTRIOS supports several simulation modes to provide rail industry stakeholders with optimal strategies for implementing greenhouse gas emissions (GHG) reduction technologies and making necessary infrastructure changes.

ALTRIOS combines locomotive and energy storage technology modeling with a robust suite of train dispatch and corridor simulations alongside a high-level train scheduling and routing tool. It uses a physics-based simulation of individual trains and real-world rail infrastructure to evaluate the effectiveness of different decarbonization technologies — including hydrogen, biofuels and batteries, among many others — across the U.S. over the course of decades.

The U.S. transportation sector accounts for a third of the country’s GHG emissions. The federal government earlier this year announced a plan for decarbonizing the transportation sector by 2050.

“The Class-I North American railroads have already committed to reducing their GHG emissions by setting science-based carbon reduction targets,” said Garrett Anderson, a lead engineer in SwRI’s Powertrain Engineering Division. “Railroads are using fuel efficiency, renewable fuels and alternate propulsion approaches to achieve the goal. ALTRIOS can cost-effectively assess locomotive decarbonization approaches using computer modeling to help them choose the right technologies for their needs.”

ALTRIOS was funded by the U.S. Department of Energy’s Advanced Research Projects Agency — Energy (ARPA-E) as part of the LOCOMOTIVES (Lowering CO2: Models to Optimize Train Infrastructure, Vehicles and Energy Storage) program. It received funding of $1.5 million. SwRI helped develop the software with the National Renewable Energy Laboratory (NREL), the University of Texas at Austin, the University of Illinois Urbana-Champaign RailTec and BNSF Railway.

The SwRI Locomotive Technology Center supported the ALTRIOS project by providing an extensive collection of locomotive power, efficiency and fuel consumption data, helping with simulation and modeling work, and sharing locomotive battery testing expertise. SwRI regularly performs locomotive exhaust emission, alternative fuel and engine technology research, development and evaluations for original equipment manufacturers and railroads. SwRI’s work also supports the U.S. Environmental Protection Agency, the California Air Resources Board, the U.S. Department of Transportation and the U.S. Department of Energy.

“Southwest Research Institute has extensive expertise in large-scale propulsion systems technologies and closely collaborated with BNSF Railway to test battery-electric locomotives in California,” said Jason Lustbader, who leads NREL’s advanced vehicles and charging infrastructure research group. “The SwRI team’s collaboration, knowledge and extensive data processing and modeling helped us to make ALTRIOS the first fully validated, comprehensive model for rail decarbonization.”

The largest freight railroads in North America aim to reduce GHG emissions by 40% within the next decade. ALTRIOS is a tool designed to tackle the unique challenges facing the industry’s push for decarbonization, such as propulsion power requirements, assessing scheduling impacts and addressing the wide geographic distribution of fuel and energy supply infrastructure. According to NREL, their researchers have already used ALTRIOS to begin development of real-world decarbonization strategies.  

“It will cost billions of dollars to upgrade existing rail infrastructure for decarbonization,” said Steven Fritz, who leads SwRI’s Locomotive Technology Center. “With that much money on the line, we must carefully evaluate decarbonization proposals­­­­ to ensure they are efficiently and effectively implemented.”

ALTRIOS is publicly available for download under an open-source license and is compatible with Windows, MAC OS and Linux. For more information or to download ALTRIOS, visit Read NREL’s press release,

For more information, visit Powertrain Engineering, Locomotive, or contact Jesús Chávez at +1 210 522 2258, Communications Department, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238-5166.