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Report Number: R-261
Publication Date: 03/04/2026
In 2024, transit buses accounted for approximately 50.4% of total public transportation ridership in the United States, serving more than 3.86 billion riders. In-bus environmental quality plays a critical role in the health and safety of operators and passengers, as well as in overall system performance. Even on short trips, poor indoor air quality can cause discomfort and symptoms such as drowsiness, dizziness, nausea, and fatigue.
This report presents research findings and practical approaches to air management in transit buses to help maintain a comfortable and safe environment for operators and passengers under normal and emergency conditions, including those involving airborne infectious diseases. The report also provides a comprehensive review of existing studies and current air management practices, with a focus on system configurations and their performance.
Low-Impact Frog Design Primer and Research Roadmap
2026
Report Number: R-260
Publication Date: 02/13/2026
Improving Transit Customer Perception of Personal Security
Report Number: S-184
Publication Date: 10/30/2025
Ensuring the safety and security of customers is a core responsibility of public transit agencies. Perceptions of personal safety play a critical role in influencing travel behavior, with fear and anxiety about personal safety acting as major deterrents to transit use.
This report documents the current state of the practice related to customer perceptions of safety and security on bus and rail transit. Drawing from a literature review, a national survey of 35 transit providers, and in-depth case examples of five transit providers, this synthesis highlights strategies to improve customers’ outlook, the effectiveness of those strategies, how the strategies are communicated to the public, and the associated change in customers’ perceptions.
Low-Level DC Leakage and Fault Currents in Transit Systems: Developing a Prototype for Detection and Mitigation
Report Number: R-259
Publication Date: 10/23/2025
Low-level electrical fault currents are a phenomenon found in direct current (DC) traction systems used in public transit systems worldwide. These low-level currents are typically caused by small and sporadic failures of insulation within the electrification system, which makes them difficult to locate, measure, and control. If these faults are left undetected, existing evidence shows extensive damage to infrastructure of transit systems and that of adjacent private/public utilities could result.
This report develops a prototype system that can detect low-level faults in electrified transit systems powered by third rails.
The report is supplemental to TCRP Research Report 211: Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems.
Determination of Actual Derailment Loads on Transit Bridges
Report Number: R-257
Publication Date: 10/23/2025
Derailment loads in nearly all U.S. transit design criteria documents are similar across agencies. However, it is unclear whether horizontal and vertical derailment loads for the efficient and safe design of transit structures are reasonably accurate.
This report provides the transit industry with a reasoned basis for derailment loads on bridges. It also offers methodologies that bridge design engineers can utilize to calculate the horizontal and vertical derailment impact loading.
Use of Automatic Vehicle Monitoring, Vehicle Health Monitoring, and Diagnostic Systems by Transit Agencies
Report Number: S-185
Publication Date: 10/13/2025
Automatic vehicle monitoring (AVM) and vehicle health monitoring (VHM) are becoming more widely utilized by transit agencies across the United States. These agencies are increasingly interested in using predictive maintenance technology (PMT), artificial intelligence (AI), and other technologies, but the overall capabilities and benefits of these technologies are still emerging.
This report explores how AVM, VHM, and other technologies are utilized to monitor an array of onboard vehicle components in order to assist in the early identification of potential mechanical issues, thus supporting effective maintenance practices.
Providing Low-Income Fare Discounts at Public Transit Agencies
Report Number: S-182
Publication Date: 09/24/2025
Over the past decade, public transit agencies across the United States and Canada have increasingly adopted low-income fare discount programs to improve transit affordability and accessibility. The COVID-19 pandemic accelerated this trend, prompting agencies to reevaluate services and expand affordable transit choices. These programs offer various benefits such as fare discounts, free rides, or discounted passes.
This report documents the current state of the practice of low-income fare discount programs offered by North American transit agencies.
