Service
February 27, 2026
Modeling Safety: Union Pacific’s High-Tech Physics Train Builder Helps Build Safer, Smarter Trains
Union Pacific invests in cutting-edge technology to deliver unmatched service, safeguard people and communities, and enhance operations – and tech tools like Physics Train Builder (PTB) are helping reimagine what’s possible.
PTB uses advanced physics modeling to simulate the movement of thousands of trains traveling across hundreds of miles of track every day – recommending the safest, most efficient train builds. By optimizing weight, car position, grade and locomotive placement, PTB helps create strong, fuel-efficient trains ready to tackle steep mountain grades and winding urban routes before freight ever leaves the rail yard.
Along with being a valuable training tool for employees, PTB also serves as a real-time safety monitoring system. It issues alerts to Operating experts, who radio locomotive engineers with guidance on adjusting trip plans and track speeds to help ensure employees and customer freight arrive safely at destination.
“PTB gives me clear information I can share with crews and managers,” said Steven Terrell, senior manager-Operating Practices. “When I recommend a speed change or check a train build, it’s backed by simulation results, not just opinion. That builds trust and speeds up decision-making.”
Insights are then sent back into the system, increasing its detailed capabilities with every trip.
“Having a tool that can quickly analyze risk in detail is a game changer. Before PTB, we relied on a vendor and waited weeks for results,” Terrell said. “Now we do it in-house in minutes, which means faster learning and quicker corrective action.”
Across Union Pacific, PTB is helping teams work safer and smarter by using real-time modeling to agilely adjust to changing business needs when traffic increases or routes shift; issue alerts to reduce potential risk in daily operations; and pair locomotive engineer feedback with analytical insights to strengthen outcomes.
“PTB has streamlined many processes,” said T.J. Weisbeck, senior director-Operating Practices. “We can now finish root-cause analysis in about five minutes, and predictive analysis in a day – and it’s an easy tool to use. We can be far more efficient.”
Visit UP.com/innovation to learn how Union Pacific continually advances technologies that aid employee decision-making, enhance safety and improve efficiency. In 2026, Union Pacific plans to invest $3.3 billion to enhance its infrastructure, technology and network reach.
