argue that notice is the basis of a lawsuit against the agency. The agency, in its defense of a dangerous condition allegation, will often be forced to answer a question such as this: “If you knew or could have known (the condition alleged in the lawsuit) could happen at this location, why wasn’t it addressed before the crash occurred?” This digest seeks, in part, to assist the agency in answering that question.

B. Legal Issues Relating to the Collection of Data

Notice

Once data is collected, it is part of the agency’s records. The agency’s review and analysis of that data also becomes part of the records of the agency. Many times, data can be found on the agency website, where the agency describes trends or explains the need for a project or a particular traffic calming technique. That information, because it has been made available to the public, may be released in response to public records requests and during litigation.

Reasonable Actions

If an agency has data that indicates a road improvement could improve the functionality and safety of a road, and the agency does not complete (or begin) that improvement before a crash occurs, how can the agency defend those actions? The answer can be found in the law. The agency is required to act reasonably. Every governmental agency has limited funds. No governmental agency can fund all the recommendations or improvements identified in its planning process. Those agencies must make informed, deliberate decisions based on the best and most accurate information available to them at the time their budgeting and planning decisions are made. One such reasonable approach, adopted by many agencies, is incorporation of the concept of incremental improvements in their guidance and practices, which allows them to make small or inexpensive changes to a roadway to address a feature that needs remediation, rather than take on a larger, expensive project immediately.

Emerging Legal Areas

It should be noted that some of the cases that are referred to or cited within this digest are unreported or slip opinions as very few reported cases address the issue of using cumulative collision or predictive data in litigation. The cases are used to illustrate the concepts and to suggest a framework that could be used in the defense of claims that include elements of the use of the data described in this digest.

As an illustration of this point, few reported cases refer to the Highway Safety Manual (HSM)⁵ in the context of tort liability, even though the HSM is guidance that is generally accepted in the industry and provides a framework for data-driven safety management.

The court in Paradise Ridge Defense Coalition v. Hartman,⁶ during an environmental review process, found that the Idaho Department of Transportation and the Federal Highway Administration had not been arbitrary and capricious in their highway location selection, which was based upon the HSM’s methodology. Paradise Ridge is one of the very few reported cases that refer to the HSM as a reference or resource, although the HSM is referred to as a resource in several state laws, as discussed in a later section of this digest. As the HSM and other methods described herein become more familiar to the legal community, the law in this area will develop.

This digest explores the legal issues relating to collecting, storing, and using data collected by the state transportation department and provides guidance to transportation professionals who use cumulative, proactive, and predictive data to guide their asset management decision-making process. This digest is also intended to assist legal counsel in defending claims related to these issues.

II. SUMMARY OF RESEARCH AND RESOURCES

This section contains a summary of the findings of this digest. The concepts are further defined and illustrated throughout the digest. As noted, predictive and cumulative data is not yet commonly used in the prosecution or defense of tort claims, at least as noted in the reported cases. It is an area that merits further research and review as trends and cases evolve.

A. Data

Data is one tool in the engineering judgment toolkit. It is not a new tool, but data is more abundant than ever before. The data varies in quality and relevance. In order to be incorporated into the decision-making process, it must be reviewed methodically and used along with engineering judgment to select and prioritize treatments to achieve the goals of the agency. Data-driven prioritization processes are discussed extensively in this digest.

B. FHWA Guidance

FHWA guidance sets out a process that a state transportation agency can use to methodically incorporate data into its strategic planning mechanisms.⁷ The seven-step process includes:

1. development of a plan for a safety governance program,
2. assessment of the current safety data program,
3. establishment of a governance program,
4. development of tools and technology for data management,
5. development of an action plan,
6. documentation of the business plan, and
7. implementation of the business plan.

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⁵ AASHTO, HIGHWAY SAFETY MANUAL, https://highways.dot.gov/safety/data-analysis-tools/highway-safety-manual (last visited Dec. 10, 2025).

⁶ 757 F. App’x 536 (9th Cir. 2018).

⁷ FHWA, Safety Data Management and Governance, FHWA SAFETY PROGRAMS, https://highways.fhwa.dot.gov/safety/data-analysis-tools/safety-data-management-and-governance (last visited Dec. 1, 2024).

C. Safe Systems Approach

The Safe Systems Approach (SSA) is flexible and context sensitive—it does not require the state to include every conceivable strategy or countermeasure in a project. Within the framework, multiple strategies are suggested to address intersection, interchange, and other system enhancements. When it incorporates evidence of its consideration of multiple strategies or countermeasures for the locations it sought to improve, the state can develop its defense to a lawsuit.

The SSA encourages the transportation agency to build layers of protection into the road system and plan for the possibility of human error; however, the highway agency is not the only element in the system. The SSA assumes that the traveling public and other participants in the process, such as vehicle manufacturers and medical experts, will take reasonable steps to protect themselves and other users of the transportation system. The SSA, along with the Highway Safety Manual and other similar methodologies, proposes strategies and countermeasures that have not been generally accepted by the transportation industry until recently. Some of those methodologies continue to be under review and subject to testing in the field. As state departments of transportation (DOTs) systematically improve their roadways and test the new methods, the newer strategies with merit can be incorporated into transportation infrastructure.

D. Incremental Improvements by the State Agency

Government agencies operate on a budget and have a duty to be responsible with their limited funds. They must use a deliberate and reasonable approach in determining where money is to be spent. A reasonable public agency considers its budget and financial obligations and other issues when it becomes aware of a condition in need of remediation. Incremental improvements can be made to a location before expensive large-scale improvements can be funded and built. Use of those incremental improvements may address the conditions or address accident history at the location without the attendant expense.

E. Liability Neutral Language

The language used in internal technical publications and guidance can be framed to provide technical solutions with flexibility in design and field practices. This concept is referred to as “Liability Neutral Language.”⁸

Technical guidance could contain references to the Federal Highway Administration’s highway design guidance, which references the use of “practical and feasible” design concepts.⁹ Similarly, the Highway Safety Improvement Program (HSIP)¹⁰ outlines the steps used by the state to conduct a vulnerable road users (VRU) analysis. The HSIP contains language that encourages the agency to balance policy interests such as budget and engineering priorities. Rather than “policy” or “standards,” refer to guidelines as “resources” or “reference materials.”

Language used in technical guidance—such as “the design concepts, procedures, and technical information are presented as guidelines and are intended to be applied with the use of sound engineering judgment and attention to the specific needs of the context of the project or improvement”—encourages the practitioner to develop context-sensitive solutions when locations that can be improved are found. That language also decreases the likelihood of creating liability by providing a range of treatments rather than one specific solution to a problem.¹¹

F. Technical Publication Reviews

The agency can benefit from regularly scheduled reviews of its guidance and other resources. Some of the basic items to consider include an evaluation of whether the practices identified in the guidance are feasible and reasonable and the “tone” of the guidance. The use of an implementation period for new guidance (i.e., a goal of 10 years to replace chevrons needed for 12,000 miles of road) is a reasonable way to implement new requirements. As a reference, the use of an implementation plan, based upon the agency’s priorities, is outlined in the 2024 edition of the Manual of Uniform Traffic Control Devices (MUTCD)¹² as an option for compliance.

G. 23 U.S.C. § 407 Protections

23 U.S.C. § 407 protections from litigation for data collected for safety purposes can be preserved by the agency.¹³ Practices for protection include restricting the release of data outside of the organization and watermarking or otherwise marking every page of data or a report with the legend “this information is protected from use in discovery and litigation by 23 USC § 407.”

H. Documentation of the Engineering Judgment Process

Documentation of the engineering judgment process of the agency can be used to defend claims relating to the actions of the agency because it shows the actions of the agency were reasonable. Evidence of compliance with internal and industry guidance can be shown using the documentation of the agency’s decision-making process.

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⁸ See Terri Parker, NCHRP Legal Research Digest 83: Guidelines for Drafting Liability Neutral Transportation Engineering Documents and Communication Strategies, Transportation Research Board, Washington, D.C. (2020).

⁹ 23 C.F.R. § 625.2.

¹⁰ 23 U.S.C. § 148(l).

¹¹ Additional information on this concept can be found here: Darren Torbic, Karen Dixon, Ingrid Potts, Elizabeth Wemple, Daniel Cook, Douglas W. Harwood, John Campbell, Brelend Gowan, and Jennifer Ogle, NCHRP Research Report 1140: Quantitative Safety Analyses for Highway Applications, Appendix A: Style and Usage Guide of Terms and Phrases to Be Used and Avoided in HSM2, Transportation Research Board, Washington, D.C. (2025).

¹² FHWA, Manual on Uniform Traffic Control Devices for Streets and Highways, MANUAL ON UNIFORM TRAFFIC CONTROL DEVICES (MUTCD), https://mutcd.fhwa.dot.gov (last visited Dec. 10, 2025).

¹³ 23 U.S.C. § 407 (Discovery and admission as evidence of certain reports and surveys).