Document Library

Connected and automated vehicles (CAVs) rely on digitally acquired traffic state information for real-time maneuver decisions, making them vulnerable to cyberattacks that manipulate perceived traffic states or communication channels. Such manipulation can subtly alter vehicle behavior and, in interactive traffic environments, may propagate disturbances beyond the attacked vehicle. The objective of this study is to develop frameworks for (i) detecting abnormal lane-changing under cyberattacks and (ii) enabling robust decision-making under adversarial conditions. For detection, a physics-guided neural network integrating a game-theoretic lane-changing model with LSTM learning is developed and evaluated using the I-24 MOTION dataset under simulated false data injection and denial-of-service attacks. Results show improved prediction accuracy and effective detection of falsified lane-changing behaviors. For robust control, a hierarchical adversarial reinforcement learning framework is proposed for discretionary lane-changing under bounded perturbations. Simulation results indicate improved traffic efficiency while maintaining safety under worst-case perturbations. These findings provide a modeling foundation for cybersecurity-aware monitoring and robust tactical decision-making in CAV systems.

This document supports implementation of system-level transportation asset valuation, helping agencies translate asset inventories and condition data into meaningful measures of asset value. The resource provides case studies, worksheets, and outreach materials that demonstrate how agencies can apply asset valuation methods to support financial reporting, communicate infrastructure needs, and evaluate investment strategies.

Practitioners will gain practical guidance on using asset valuation to track system condition trends, demonstrate the impact of funding decisions, and strengthen transportation asset management (TAM) programs. The materials complement the AASHTO Asset Valuation Guide and include tools that help agencies integrate asset valuation concepts into planning, performance management, and investment decision-making.

This synthesis examines how State DOTs fund, manage, and coordinate the maintenance of Complete Streets infrastructure, including bicycle, pedestrian, and other active transportation facilities. As agencies expand multimodal networks, the report highlights practical challenges such as equipment compatibility, staffing capacity, and ongoing maintenance funding.

Practitioners will find examples of maintenance policies, interagency cost-sharing agreements, and partnership models involving local and tribal governments. The report also identifies strategies for workforce training, equipment procurement, and operational coordination that can help agencies sustain Complete Streets investments over time.

NCHRP Synthesis 659: Automated Traffic Signal Performance Measures: Management, Operation, and Maintenance examines how state departments of transportation are using high-resolution traffic signal controller data to monitor, manage, and improve signal performance. Automated Traffic Signal Performance Measures (ATSPMs) enable continuous, data-driven oversight of traffic operations and maintenance, supporting more proactive and efficient decision-making. While the benefits of ATSPMs are well documented, adoption across state DOTs varies due to challenges such as funding constraints, equipment and technology upgrades, staffing capacity, and organizational readiness. The synthesis highlights current practices, including the use of both controller-based and crowdsourced signal performance measures. It also explores implementation barriers, funding strategies, staffing considerations, and examples of how agencies integrate ATSPMs into day-to-day operational and maintenance workflows.

NCHRP Research Report 1149: Estimating Benefits of Closing Gaps in Active Transportation Networks: A Guide provides practical methods for evaluating the benefits of projects that improve connectivity in walking, bicycling, and rolling networks. Active transportation systems—including trails, sidewalks, bike lanes, and connected roadways—play a critical role in supporting safe, convenient travel for both recreation and everyday trips, yet many communities face fragmented networks with significant gaps. This guide offers accessible analytical approaches that can be applied across diverse geographies and project types, using publicly available datasets and research-based multipliers. Designed for broad usability, the methods rely primarily on national-level data sources to help agencies consistently estimate economic, safety, health, and mobility benefits.

NCHRP Web-Only Document 426, which accompanies the report, documents the development of the guide and summarizes the full research effort behind the recommended methodologies.

NCHRP Research Report 1164: The Business Case for Knowledge Management: A Guide provides state departments of transportation and other transportation agencies with practical tools to assess and measure the value of knowledge management (KM) initiatives. As experienced staff retire and collaboration across disciplines increases, agencies face growing challenges in preserving institutional knowledge and ensuring effective knowledge transfer. The guide outlines approaches for evaluating how KM practices contribute to improved business processes, workforce development, and organizational performance. It helps agencies articulate the return on investment of KM activities and integrate them into broader performance management strategies.

Accompanying the report, NCHRP Web-Only Document 437: Assessing and Measuring the Business Value of Knowledge Management documents the research effort and provides additional detail supporting the guide’s development.

This publication explains how the FHWA Long-Term Pavement Performance (LTPP) database underpins modern pavement performance modeling and performance-based investment decisions. For practitioners, it outlines how LTPP data are used to calibrate and validate Pavement ME design procedures, establish national data collection standards, and support statistically robust performance comparisons under real-world conditions. Agencies interested in strengthening pavement performance forecasting, improving lifecycle cost estimates, or validating local design assumptions will find this a useful overview of available data tools and access points.

This research presents a quantitative framework to help agencies evaluate trade-offs between safety, efficiency, and equity when redesigning urban streets for multimodal operations and connected/automated vehicle (CAV) integration. The study introduces two complementary tools: a Network Fundamental Diagram (NFD)-based optimization model for system-level performance planning and a multi-agent simulation platform that evaluates real-world interactions among vehicles, pedestrians, cyclists, micromobility, and emerging modes.

Practitioners will gain insight into how to move beyond qualitative Complete Streets guidance by applying measurable objectives—including accessibility gaps, sufficiency thresholds, and maximin equity principles—to corridor and network design. The framework also incorporates advanced safety metrics (e.g., Time-to-Collision and impact severity) to evaluate both conflict likelihood and consequence. Case studies demonstrate how agencies can transparently compare design alternatives and make evidence-based decisions when trade-offs are unavoidable.

Alternative URLs for accessing the report:

https://figshare.com/articles/preprint/Making_CAV_Deployments_Compatible_with_Complete_Streets_Objectives_for_Safe_and_Efficient_Operation_Phase_II/31021405?file=60862168

https://www.dropbox.com/scl/fi/i5ozwm8a4tlje16u6hwjq/Making-CAV-Deployments-Compatible-with-Complete-Streets-Objectives-for-Safe-and-Efficient-Operation-Phase-II-Final-Report.pdf?rlkey=yajzaiq1q36osh1zkiclhv69w&e=1&st=8ofgbte4&dl=0

PIARC: Impact of the Development of Active Transport Modes in Road Tunnels – Current Situation Report and Case Studies examines the growing integration of active transportation modes—such as pedestrians, cyclists, and other vulnerable road users—within road tunnel environments. As cities seek to improve mobility, accessibility, and emissions outcomes, tunnel owners and operators face new safety, design, and operational challenges when authorizing active modes in these confined facilities. This international report compiles and evaluates case studies from around the world, highlighting how tunnels are being constructed or retrofitted to safely accommodate active users through infrastructure adaptations, equipment upgrades, and revised operational procedures.

The document categorizes examples into four approaches: tunnels with safety galleries usable by active modes, tunnels with protected spaces for active users, tunnels with specific geometric or operational adaptations, and tunnels dedicated entirely to active mobility. Drawing on global expert contributions, the report outlines the state of practice and identifies key considerations for safety, risk management, and coordination with emergency services. It provides a foundation for future recommendations to guide decision-making by tunnel owners, designers, safety professionals, and transportation agencies considering active mode integration.

This conduct of Research Report for NCHRP Project 20-44(40) was submitted July 2025. It accompanies the Transportation Agency Capability Building Web-Based Guide in order to support implementation efforts and build upon the framework established in NCHRP 20-24(95) and facilitate the use of ACB guidance by transportation agencies. Practitioners may also find the Performance Management Reporting Peer Exchange Final Report – NCHRP Project 20-24 Task 124 (2019) of interest as well.

The Using Performance Management to Respond to Uncertainty Peer Exchange was a collaborative forum designed to facilitate the sharing of noteworthy practices and lessons learned in applying transportation performance management (TPM) approaches to manage unexpected disruptions and changes. The peer exchange brought together State DOTs, FHWA, and other transportation agencies to discuss the latest strategies, tools, and resources for improving transportation agency adaptation. The peer exchange aimed to apply and advance TPM practice to help agencies respond to uncertainty, foster a collaborative environment to improve outcomes using performance management, and engage in peer-to-peer problem-solving, sharing noteworthy TPM practices, and exploring innovative solutions to enhance transportation agency adaptability in the face of uncertainty. This summary details the content, discussions, and resources shared during the peer exchange.