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Traffic analysis has traditionally focused on motorized travel, but transportation agencies increasingly need to assess conditions for people walking, bicycling, and using mobility or micromobility devices. Although multimodal analysis methods are available, limited information exists on how state departments of transportation (DOTs) incorporate nonmotorized traffic analysis into routine planning, design, and operations.

NCHRP Synthesis 671: Traffic Analysis Practices for Nonmotorized Modes, produced by TRB’s National Cooperative Highway Research Program, includes information on how state DOTs define and analyze nonmotorized modes, including pedestrians, bicyclists, mobility device users, and micromobility; the tools, data sources, and performance measures used in practice; and the institutional, technical, and operational challenges associated with integrating nonmotorized modes into planning, design, and operations. The report also documents emerging approaches such as level of traffic stress, multimodal level-of-service methods, statewide count programs, and the use of GIS-based and data-driven analytical tools.

This study develops a transferable framework for the analysis of three low-cost safety improvement projects installed on state highways in Oregon; specifically Rectangular Rapid Flashing Beacon(RRFB), Shoulder Rumble Strips (SRS), and Two-Way to Four-Way Stop Conversion. A before-after EB study was performed for RRFB and SRS. A cross-sectional analysis was conducted for stop control conversion in the absence of installation data. For RRFB, the Crash Modification Factor (CMF) for total pedestrian crashes was found to be 0.481. The total crashes and rear-end crashes were also found to have reduced by 27% and 14%, respectively. The CMF for total crashes and run-off-road crashes in the presence of SRS was found to be 0.72 and 0.73, respectively. The result from the cross-sectional analysis suggested that four-way stops are associated with approximately a 15.7% reduction in crashes compared to two-way stops.

As the existing steel infrastructure inevitably continues to age and deteriorate, engineers are increasingly looking for innovative and effective methods for repairing and maintaining existing steel bridges, which are susceptible to corrosion damage when exposed to aggressive environments and deicing salts. Conventional methods for repairing steel bridges can be labor intensive and time consuming and add considerable weight to the existing structure. One alternative is to utilize carbon fiber reinforced polymers (CFRPs). Many studies have documented CFRP’s ability to enhance the strength of existing structures while having a high strength-to-weight ratio and the added benefit of being noncorrosive. However, most of these studies have focused on the bond behavior between CFRP and steels having a smooth surface condition, which is not representative of deteriorated structures in need of retrofitting. Further research has examined the durability of CFRP-steel bonds but under conditions that do not reflect the service life conditions for typical bridge applications.

This study examined the effects of the surface condition and environmental exposure on the bond between steel and two different CFRP materials, one having a normal modulus and the other an ultra-high modulus. The researchers evaluated the influence of corrosion and simulated corrosion pitting to determine whether structures with non-uniform surfaces are viable candidates for CFRP retrofits. In addition, the durability of CFRP-steel bonded, double-strap jointed specimens was investigated through laboratory hygrothermal aging and chloride exposure, as well as in situ environmental conditioning to multiple environments in Virginia. The study also included a small subset of fatigue-tested specimens, as well as a hypothetical in situ cost comparison to assess the economics of strengthening steel structures using the CFRP materials used in this project.

The results showed that although a corroded steel surface does require a longer bond length compared with a smooth surface, a pitted surface due to corrosion has no negative effect on the bond strength between CFRP and steel. Furthermore, exposure to chlorides does not appear to affect that bond strength. However, strength reduction factors for hygrothermal and environmental aging should be included in the design to account for exposure to given conditions. Nevertheless, CFRP is a costeffective method for strengthening corrosion-damaged steel members with moderate levels of surface pitting. The research can be useful in the development of guidelines that will assist engineers determine if a CFRP retrofit solution is applicable in a given environmental setting and appropriate for the level of deterioration of the structure

Transportation agencies throughout the United States have been steadily designing and implementing a variety of alternative intersections and interchanges (AIIs) to address unique safety and operational problems. However, despite the growing number of AIIs, high-quality crash prediction models and crash modification factors (CMFs) used to quantify the benefits of these designs remain limited.

NCHRP Research Report 1195: Developing Crash Modification Factors for Alternative Intersections: A Guide, produced by TRB’s National Cooperative Highway Research Program, includes an abbreviated literature review focusing on the three types of AIIs studied and potential analysis methods, as well as a discussion of data collection and analytical approaches. It summarizes the results of CMF development and presents a case study on the use of safety performance functions (SPFs) in future analyses. The report also presents the movement-based SPF framework and results, documents a microsimulation case study, and offers suggestions for implementing the CMF findings and conducting future research.

Over the past few years, considerable roadway damage has occurred in Vermont due to intense precipitation, leading to upslope landslides and debris flows (mixtures of boulders, trees and slurries) spilling onto roadways. Although landslide occurrence has a long history in the State, the debris flow phenomenon addressed in this work is relatively new to Vermont and needs further attention. The work is focused on non-channelized debris flows, that is, debris flows not specifically associated with gullies and channels developed through fluvial processes. Identifying areas susceptible to such debris flows and monitoring of these areas will facilitate asset management, improve roadway safety, potentially reduce the need for emergency road closures and help reduce long-term costs associated with repeated emergency responses. The susceptibility to debris flow is influenced by several factors such as slope angle, slope materials and rainfall intensity. The key outcome of this study was to create a map identifying high-hazard areas (susceptible to debris flow) for awareness, asset management and monitoring. We considered rainfall as the triggering factor to initiate debris flow and merged rainfall data with topographic and soil parameter data to produce a debris flow factor of safety map for a study area comprised of a 152 m (500 ft) buffer zone on either side of national and state routes. Three factor of safety groupings categorize the terrain in the buffer zone into stable, marginally unstable, and unstable, and thereby the debris flow potential in the design rainfall triggering scenario.

The South Dakota Department of Transportation (SDDOT) uses a traditional approach to construction inspection and material testing. Research in the early 1990s, Project SD91-05: Essential Testing and Inspection Levels help set the current inspection and testing program. Due to this report being more than 30 years old, SDDOT has taken steps to review the feasibility of implementing risk-based approaches to construction inspection and material testing. Risk-based approaches focus on the value of each material test and inspection type, helping agencies direct resources to where they provide the most value and reduce the risk to end quality and performance. This, in turn, reduces impacts on cost, schedule, and safety. Therefore, due to limited resources, this research project investigates the current construction material testing and inspection program to determine frequencies and, if appropriate, modify it using risk-based approaches. To accomplish this, the research team conducted an intensive literature review, focus group interviews with SDDOT personnel and third-party contractors and consultants, and case studies with five state DOTs. A risk assessment was conducted using a list of material testing and construction inspection activities. Each activity was rated by 19 SDDOT field personnel, and an average expected value was calculated to identify the top-risky material testing and construction inspection activities. The risk assessment condensed down the list of material testing activities to 72 and construction inspection activities to 35. Then, a quantitative analysis of material testing and construction inspection data for 189 projects from the material sampling and testing (MS&T) was conducted. This analysis confirmed the risk assessment and yielded failure rates for material testing activities. Furthermore, the rankings were validated using construction inspection diaries (287 field events across 51 projects, 2020-2026), with nearly 90% of the top-ranked inspection activities confirmed by field evidence. A staffing analysis of 83 projects found that inspection effort tracks project size rather than activity risk and is concentrated among a few lead inspectors, which reinforces the case for a risk-based program that directs limited resources to where they add the most value. The results of the data collection, review, and subsequent analyses result in a series of recommendations and priorities to adjust material testing and construction inspection frequencies at SDDOT using risk-based approaches.

Although physical visibility is often assumed to ensure driver awareness, relatively little naturalistic evidence describes how drivers perceive vulnerable road users (VRUs) across real-world driving contexts. This study examined roadway and driver factors associated with detection of pedestrians, cyclists, and motorcyclists using synchronized multimodal data. Twenty-four participants completed two naturalistic drives over a fixed route representing rural, suburban, campus, and urban environments. Driver gaze was recorded using Tobii Pro Glasses 3, vehicle data using a CANbus/GNSS-IMU logger, and heart rate using a Polar H10 sensor. The synchronized dataset contained 3,526 annotated VRU encounters. Mixed effects logistic regression identified factors associated with successful detection. Vehicle speed was the strongest factor, with each 1-mph increase associated with an approximately 5% reduction in detection odds (OR = 0.95, p < 0.001). VRUs on the right side of the roadway were twice as likely to be detected as those on the left (OR = 2.00, p < 0.001), and detection was higher in rural than urban environments (OR = 4.55, p = 0.019). Findings support speed management, context-sensitive roadway design, and driver-assistance systems to improve VRU safety.

VDOT is responsible for the routine maintenance of a large crosswalk inventory. As high-visibility crosswalks (HVCs) have higher costs than transverse crosswalks, appropriate deployment is important. This report summarizes existing research regarding the contexts in which HVCs are effective, a survey of crosswalk marking practices in Virginia localities, and a study of HVCs and transverse crosswalks on Virginia roads at signalized intersections.

This study evaluated the differences between AASHTOWare Pavement ME Design (PMED) Version 2.6 and Version 3.0 using
representative Indiana pavement structures and traffic conditions. PMED Version 3.0 introduces several major updates, including
adoption of the MERRA-2 climate database, revised rigid pavement slab-base interaction models, updated calibration coefficients,
and support for Multiple Stress Creep Recovery (MSCR)-based asphalt binder grading. Because the Indiana Department of
Transportation (INDOT) currently uses PMED Version 2.6 with locally calibrated distress models, evaluation of Version 3.0 was
necessary prior to implementation.

A total of 114 pavement design files representing full-depth asphalt pavements, asphalt overlay pavements, and Portland cement
concrete (PCC) pavements, were analyzed using both PMED Version 2.6 and Version 3.0. Level 1 and Level 3 analyses were
conducted, and predicted pavement distresses, including International Roughness Index (IRI), ruting, fatigue cracking, thermal
cracking, faulting, and transverse cracking, were compared.

The results indicated that PMED Version 3.0 generally produces pavement performance predictions consistent with those from
Version 2.6 for most distress indicators. The largest differences were observed in thermal cracking predictions, particularly for
asphalt overlay pavements, where Version 3.0 generally predicted higher cracking levels than Version 2.6. For PCC pavements,
Version 3.0 predicted lower IRI values and moderate differences in faulting and transverse cracking. MSCR-based asphalt binder
grading was successfully implemented in Level 3 analyses; however, software errors occurred during Level 1 analyses.

Overall, the study demonstrated that PMED Version 3.0 Level 3 analyses can be implemented for pavement design applications in
Indiana because the overall pavement performance prediction trends remain generally consistent with those from Version 2.6.
However, implementation of Level 1 analyses is recommended after appropriate thermal cracking input properties are developed
and validated through the ongoing SPR-4912 study

Time allowances and recovery margins in rail scheduling are incorporated into travel time estimation and minimum headways to prevent delays from affecting subsequent trains. These margins act as a buffer against service irregularities, such as variations in station dwell times and train performance, and they are a key factor in rail capacity calculations. Most contemporary tools used to analyze or construct timetables calculate running times specific to each train. However, the factors influencing running times are inherently uncertain, including human behavior, weather conditions, train composition, ongoing infrastructure projects, rolling stock, and route conditions. To accommodate these uncertainties, transit planners and agencies incorporate time allowances into running time estimation, while applying operating or recovery margins to minimum headways to limit delay propagation.

TCRP Research Results Digest 122: Operating Margin and Recovery Factor Practices for Travel Time Estimation and Rail Scheduling, produced by TRB’s Transit Cooperative Research Program, explores the methodologies used by transit agencies to estimate more robust runtimes. These methodologies, among other elements, help establish operating margins and recovery factors in rail scheduling. This research informed updates to Chapter 8 of the TCQSM 4th edition. The digest describes one of 12 small research tasks conducted to support the development of new content for the 4th edition.

The article describes the Washington State Department of Transportation’s (WSDOT) efforts to implement wildlife crossing structures, which aim to improve habitat connectivity and reduce wildlife-vehicle collisions. It highlights the state’s data-driven prioritization framework, established under the Washington Habitat Connectivity Action Plan, to identify and target high-risk highway segments. Additionally, the text underscores the importance of long-term monitoring, often done in partnership with universities, to document the ecological and safety successes of these structures.

Adverse weather conditions such as rain, snow, fog, and high winds pose significant challenges to roadway safety and mobility. These conditions not only increase the risk of crashes but also contribute to travel delays, congestion, and unpredictable driving behavior. To mitigate these risks, transportation agencies are increasingly deploying variable speed limit (VSL) and real-time warning (RTW) systems, which use real-time data to dynamically adjust speed limits and provide timely hazard alerts.

NCHRP Research Report 1176: Real-Time Warnings and Variable Speed Limits— Safety and Travel Reliability During Weather Events, produced by TRB’s National Cooperative Highway Research Program, is a guide designed to support transportation professionals in understanding, evaluating, and implementing these systems in response to adverse weather conditions. The strategies and case studies included in this guide are intended to help transportation agencies enhance roadway safety, improve traffic flow, and ensure drivers receive accurate, timely information to navigate hazardous conditions effectively.

The same project that produced NCHRP Research Report 1176 also documented its methodology and findings in NCHRP Web-Only Document 447: Evaluating the Impacts of Real-Time Warnings and Variable Speed Limits on Safety and Travel Reliability During Weather Events.