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Through the Digital Right-of-Way (ROW) and Mobility Improvement Project, the City of Philadelphia developed and implemented a set of new technologies to test digital management of the right-of-way (ROW). Traditionally, as in other cities, Philadelphia issues regulations on how roadways and sidewalks may be used or blocked, and posts physical signs that users must read, interpret, and follow to use the street safely and legally. The Smart Cities team, in partnership with the Streets Department, Open Mobility Foundation, and several vendors, tested communicating these right-of-way regulations and closures digitally, such that a user’s phone or vehicle could receive them, parse out relevant information for specific location/day/time and turn it into guidance for the user - for instance, should the user park or not, and if a user is blocking a bike lane or not.

One of the most important deliverables for the project was the development of the Right-of-Way Data Specification (ROWDS), a formal way to standardize and structure City ROW rules for computers to use, and its implementation through Road Rules, a software product by the company INRIX. These technologies have helped increase the spatial resolution (the level of detail for mapping small areas) of the underlying basemap to match what the Streets Department needs to operate. The project also demonstrated that higher spatial resolution can help the city better manage street-closure permitting. As this project is operationalized through a citywide deployment, it will pave the way for an improved user experience for everyone who uses the roads and a more efficient permitting system for the City of Philadelphia.

This report investigates vulnerabilities in New Zealand’s strategic road network that could cause disruptions. The project identifies critical vulnerabilities that impact the national freight network and strategic supply chains, incurring significant costs to end users, and identifies mitigation activities to reduce these vulnerabilities. The analysis includes crucial nodes and linkages, predicting the impact of their unavailability on supply chains. The report highlights the importance of competition in the freight sector, noting that an oligopolistic structure often drives inefficiencies and increased costs. We identify short-term (up to 1 day), medium-term (up to 1 month) and long-term (3 months or longer) closure timeframes as defined by users, outlining their respective impacts and contingency plans. In short-term closures, contingency plans typically involve dynamic decisions, carrying safety stock and delaying shipments. Medium-term closures see a shift towards using rail and sea transport and offshore storage in containers for warehousing. Long-term closures emphasize sea transport and adaptive decision making even more, with significant variations in response based on the specific business and level of uncertainty involved. We use economic impact computable general equilibrium modelling and stakeholder engagement to inform the need to strengthen or build redundancy into the freight system, focusing on road transport. Findings indicate regional variations in freight cost impacts and suggest the importance of adaptive planning for deeply uncertain events. The report emphasizes economic impacts, not financial costs, and provides insights into contingency plans and their effectiveness in different scenarios.

Corrosion of buried steel, a critical component of American transportation infrastructure, remains one of the most insidious challenges due to the uncertainty associated with its estimates. Predicting when and how this corrosion happens is very difficult. This uncertainty grows exponentially with time, making corrosion estimation in the long term even more challenging, especially with buried steel and steel structures, which cannot even be monitored visually. While significant advancement has been made to understand the effect of the various corrosion parameters on soil corrosivity, there is a lack of a comprehensive understanding of how these factors collectively contribute to corrosion as they vary simultaneously and continuously with time. This project evaluates soil resistivity and corrosivity in controlled, constant conditions, considering the various key parameters that contribute to corrosion of buried steel. The project involved devising a new experimental protocol and developing and implementing a comprehensive experimental program by varying one testing parameter at a time. The results of the testing program showed the potential of the experimental approach to provide the necessary data to develop empirical prediction models for soil resistivity. Additionally, a new experimental method was piloted for this project to capture the variation in soil resistivity in a continuously varying environment. Finally, the researchers compiled a large digital database of real-world corrosion measurements and site information. Using advanced data analysis techniques, they created a model that can help predict corrosion in buried steel structures and estimate the level of uncertainty in those predictions. Better predictions of corrosion can help engineers and infrastructure managers identify risks earlier, plan maintenance more effectively, and extend the life of critical infrastructure such as pipelines, bridges, and transportation systems, therefore helping to reduce costly failures, improve safety, and support more reliable systems.

Spray-on rejuvenators are pavement preservation treatments intended to mitigate oxidative aging of asphalt binder in the nearsurface region of asphalt pavements. Although several highway agencies have evaluated these treatments, reported performance outcomes vary, and the Virginia Department of Transportation (VDOT) has limited documented experience with their use. Prior to this study, VDOT did not have an established specification or standardized evaluation framework for spray-on rejuvenators. This study was conducted to evaluate the feasibility and short-term field performance of spray-on rejuvenators under Virginia conditions and to support the development of guidance for potential future implementation. The scope included a comprehensive review of published literature, agency specifications, and state-of-practice documents, along with field trials conducted in the Lynchburg and Northern Virginia districts. Following completion of the Lynchburg District field trials, a special provision was developed to guide spray-on rejuvenator application practices and was implemented for the Northern Virginia District field trials.

Some types of geometric improvements that the Virginia Department of Transportation (VDOT) has begun to build in the past two decades, such as the reduction in the number of arterial access points, the replacement of a traditional four-way intersection with a roundabout, or a restricted crossing U-turn, or left-turn prohibitions, have elicited expressions of concern from businesses that operate on property adjoining the improvements. The business operators’ concern is that the improvement, by creating more circuitous access for motorists, will reduce customer traffic, with a consequent effect on the business’s revenue or on the value of the affected commercial parcel. VDOT has never compiled a quantitative, Virginia-specific dataset on how access changes have affected adjacent businesses. This study sought to fill that deficit by estimating the effects of changes in access on assessed parcel values before and after a VDOT reconstruction that altered the geometrics of an intersection or a road segment. Although business impacts could ideally be measured as taxable sales, such data were not feasible to obtain, and thus, assessed parcel values were the study focus. The study compiled information on 91 commercial properties fronting VDOT reconstruction projects and on 67 similar commercial properties nearby, not fronting the projects, at 30 VDOT projects in 16 counties and three independent cities. Information collected included two different measures of the change in motorized access—the number of additional turns and additional distance traveled—that resulted from construction and assessed real estate values during a nine-year window from four years before the year construction was completed to four years after the year of construction completion. This nine-year window was sampled to have a strong opportunity to capture the lagged effects of changes in access in case such changes were not immediately reflected in project assessments. The analysis found that, within the nine-year window, the changes in access that the investigators measured had no statistically distinguishable effect on the property value assessments of the commercial properties fronting the VDOT reconstruction projects.

A previous study by Blomberg and Cleven (1998) developed a pedestrian safety zone approach in Phoenix, Arizona, and Chicago, Illinois, focusing on pedestrian safety countermeasures in subsets of the cities that had experienced a high number of crashes involving people 65 and older. It proved efficient deploying countermeasures, significantly reducing the targeted pedestrian crashes in Phoenix. This original zone process, however, still needed significant resources to address the entire city, and required a relatively long time to plan and implement. The primary objectives of the present study included adapting the previous zones approach to be implementable quickly by cities using their resources and demonstrating the resulting low-cost pedestrian safety zones approach in several cities. Three cities—Gainesville, Florida; Kalamazoo, Michigan; and Saint Paul, Minnesota—agreed to demonstrate the low-cost zones approach. Each site prepared a case study report documenting the activities reported here. The approach appeared flexible and effective in all three cities. The discussion section of this report includes ideas for supporting more widespread use of the technique.

Fatigue failure of highway sign structures due to sustained wind-loading events has been recognized in many states. In fact, the American Association of State Highway and Transportation Officials specifies that the structural component should be designed for infinite life by maintaining wind-induced stress below their constant amplitude fatigue threshold. However, because existing structures are typically not designed for fatigue, the condition of all critical and fatigue-prone components must be evaluated for safety. Visual inspection requires extensive time and effort and may not detect unnoticed fatigue cracks, so growing attention has focused on analytical inspection tools to examine all critical members and connections for remaining fatigue life to ensure public safety. The reliability of these analytical tools depends on the accuracy of wind-loading models applied during the life span of the structure. This study devised a fill-interpolate-extend approach to furnish a wind-loading data ensemble for the duration of analysis. The ensemble established a reliable synthetic wind model to generate fatigue cycle counts. In addition, a comprehensive analytical framework, including structural modeling, stress extraction/processing, and fatigue damage simulation, was integrated to yield an affordable tool that is applicable to various sign structures topologies. The resulting software for non-cantilever overhead structures as well as cantilever and butterfly assemblies were successfully verified to predict real cases for fatigue damage, reflecting the in-situ condition of the structures.

Traditional crash-based intersection monitoring fails to capture the critical near-miss events that precede collisions involving vulnerable roadway users (VRUs). To provide a proactive alternative, this report investigates how emerging roadside LiDAR and AI/ML technologies can enhance intersection safety observability through three interconnected research thrusts. First, an infrastructure-based sensing survey identifies LiDAR as a premier primary modality due to its high geometric precision and robustness under varying lighting conditions. Second, a systematic study simulating vertical beam loss across six 3D detection architectures establishes a critical 20% beam-loss maintenance threshold. Beyond this point, VRU detection deteriorates rapidly, with concentrated, contiguous beam loss from sensor occlusion proving far more detrimental than dispersed loss.

Building upon these foundational insights, the third thrust introduces a real-world application via an end-to-end, auditable safety-analysis framework deployed at a signalized intersection in New York City. Utilizing a newly established, manually annotated 8,000-frame roadside dataset, the framework integrates 3D detection, tracking, stabilization, and structured human-in-the-loop quality assurance to convert raw sensor data into defensible near-miss evidence. A heavy vehicle-bicycle interaction case study demonstrates that contrasting direction-agnostic and longitudinal time-to-collision (TTC) metrics can successfully isolate lateral-intrusion conflict mechanisms that single-metric approaches miss. Together, these efforts validate roadside LiDAR as a scalable, interpretable, and highly defensible tool for proactive traffic safety management.

State and local transportation agencies increasingly rely on proactive safety analysis to inform roadway design and improvement decisions before crashes occur. However, uncertainty regarding the potential use of proactive safety methodologies, manuals, and guidance in tort litigation has raised concerns about increased exposure to liability.

NCHRP Legal Research Digest 95: Addressing Liability Issues of Proactive Safety Improvements, produced by TRB’s National Cooperative Highway Research Program, examines the legal considerations facing transportation agencies that adopt proactive, data-driven approaches to roadway safety. The digest reviews relevant statutes, case law, and agency practices; identifies litigation in which proactive safety concepts have been raised; evaluates defenses and outcomes; and documents strategies used by transportation agencies to mitigate liability concerns. Based on this analysis, the research explores potential legal, administrative, and policy approaches that may support the use of proactive safety methods while preserving established processes for prioritizing and funding roadway improvements.