CHAPTER 11

Guide Development

Introduction

This chapter presents how the guide was developed. The guide is based on the current state of practice identified in the literature review, the identified data needs, and the proposed methodology. The purpose of the guide is to assist transportation agencies and practitioners in preventing and mitigating the risk of BrTS by motor vehicles. The guide covers both risk factor identification and countermeasure selection, and the order of operations is important. Specifically, it is critical to identify and understand factors that contribute to BrTS before selecting an appropriate countermeasure to target the underlying issue(s).

Guide Structure and Layout

In developing the guide, the research team balanced the information gathered throughout the project with the need to present it in a way that would be most useful to the readers. To organize the guide, the research team determined that chapters should be organized by key procedures and that each chapter should be able to stand-alone. This design ensures that users looking for specific topics or information do not need to read the entire guide. Readers should be able to quickly navigate to the desired chapter and find the relevant content. After several iterations and rounds of feedback, the following outline and content were agreed upon for each chapter of the guide.

• Executive Summary
• Chapter 1: Introduction
• Chapter 2: BrTS Risk Assessment
• Chapter 3: BrTS Countermeasures
• Chapter 4: Countermeasure Selection Process
• Chapter 5: Post-Implementation Evaluation Process
• Chapter 6: Summary
• References
• Resources

Multiple reviews by members of the research team, peer review team, and NCHRP project panel helped verify that the guide clearly presented the topics in an organizational structure that promoted easy navigation and readability. The rest of the chapter provides a brief overview of each chapter in the guide.

Executive Summary

The executive summary provides an overview of the key points in the guide. It targets individuals who may not have time to read the details (e.g., leadership and managers) but need to understand the importance of the guide for those who support their decisions. The executive summary also helps those responsible for responding to the press.

Introduction

The guide opens with an introduction to BrTS, including the following:

1. Statistics on the magnitude of the problem
   1. Number of crashes
   2. Death and injury toll
   3. Cost of crashes
      1. Cost related to death and injury
      2. Cost related to bridge and tunnel repairs
      3. Other costs (delay)
2. Explanation of the limited success to-date in mitigating BrTS
   1. Why is it difficult to identify specific locations that may warrant further analysis and potential treatment?
      1. Crashes may not cluster at a single location (but crashes across the network may share similar characteristics)
      2. Limited sample sizes and underreporting of BrTS
      3. Data quality issues related to the accuracy and completeness of crash locating
      4. Inadequacies of tunnel-strike reporting; bridge strike reporting is poor, but tunnel-strike reporting is even worse
   2. Why is it difficult to mitigate BrTS?
      5. Describe state of practice for routing oversize loads
      6. Describe state of practice for mitigating BrTS, including engineering, education, and enforcement initiatives
3. Emphasis on the importance of this guide and the related research
   1. Purpose of the guide
      1. This guidance will assist transportation agencies and practitioners in preventing and mitigating the risk of BrTS by motor vehicles. The guidance will cover both risk factor identification and countermeasure selection, emphasizing the importance of the order of operations.
   2. Target audience
      2. Identify the various target audiences. The primary audience includes permitting officials, transportation planners, traffic engineers, maintenance personnel, law enforcement officers, etc. The secondary audience includes trucking companies.
      3. Describe the specific concerns/domains of the audience segments as well as their shared concerns. For instance, shared concerns might include risk factors (e.g., novice drivers). In terms of countermeasures, transportation planners and traffic engineers may be more interested in infrastructure improvements, while law enforcement officers would likely be interested in behavioral measures.
   3. Organization of the guide
      1. A roadmap of the guide
      2. Describe where to find various content and how each target audience will access information from the chapters
      3. Note how different audiences could use the guide for specific initiatives. For example, explain how commercial motor vehicle enforcement officials can use the guide to identify risk factors and implement enforcement techniques and equipment to prevent BrTS
4. Glossary of terms
   1. Define common terminology related to BrTS and risk. BrTS terminology includes the size of loads and types and parts of the structures. Risk is defined by two components: likelihood of occurrence x impact if event occurs.

2. In addition to the glossary of terms, the guide defines terms as they arise in the text and uses callout boxes to highlight/reiterate important terms and definitions

BrTS Risk Assessment

It is critical to identify and understand factors that contribute to BrTS before selecting an appropriate countermeasure to target the underlying issue(s). It is also important to revisit known issues during design or maintenance activities. This chapter focuses on BrTS risk assessment, starting with a review of national risk factors and then describing the data and analysis procedures an agency could use to identify jurisdiction-specific risk factors.

1. Provides an overview of risk-based assessments.
2. Identifies common risk factors identified through the data analysis in earlier tasks. Potential risk factors will be discussed in detail, including the differences among facility types where relevant information is available. This section will focus on practical application of the results.
3. Highlights visualization tools such as risk matrixes (likelihood vs. consequence) or heat maps to prioritize elements. The use of these tools would depend on the type of input an agency has access to (primarily crash and location details). A risk register (i.e., a way to list risks along with corresponding mitigation measures) might be another relevant tool to include in this section.
4. Describes data needs and analysis procedures to identify risk factors and assess BrTS risk using local (state/regional) data.
5. Describes data collection procedures for updating the national clearinghouse. Our model is based on existing data (crash and NBTI). This section could include noteworthy practices and callouts for specific states OR could describe a generic state that is lacking data with an example of how that state could go about collecting or formatting data for future analysis.

BrTS Countermeasures

Once an analyst has identified the factors that contribute to BrTS, the next step is to identify appropriate countermeasures to target the underlying issue(s). This process starts with a larger list of options that are pared down to the preferred alternative through more detailed alternatives analysis. This chapter focuses on the first part of the process (general countermeasure identification).

1. Presents a summary of common BrTS risk factors with applicable countermeasures.
   1. Countermeasures and strategies include a discussion of roadway dimensions, oversize vehicle routing systems, routing compliance for oversized loads, pilot car escort guidance, and roadside and onboard vehicle technologies among others identified in the literature review.
2. Describes each countermeasure in detail, including information such as cost, effectiveness, service life, and other considerations.
   1. Countermeasure summaries include one-pagers or multipage descriptions.

Countermeasure Selection Process

There are often multiple options for addressing crash contributing factors. Given a list of potential countermeasures, the next step is to perform a more detailed alternatives analysis to identify the preferred alternative. This chapter describes quantitative and qualitative measures for selecting and prioritizing countermeasures, focusing on alternatives analysis.

1. Provides a discussion of countermeasure selection concepts such as targeting risk factors, mitigating risk to other road users, mitigating societal costs, and return on investment.

2. Provides quantitative methods for prioritizing countermeasures (e.g., benefit-cost analyses, Safe System approach). There are several related resources. As such, we do not envision recreating these materials in this chapter. Instead, we plan to provide an overview of the concepts and direct readers to readily available resources for more information. Relevant resources include FHWA’s Highway Safety Benefit-Cost Analysis Guide and FHWA’s guide Selecting Projects and Strategies to Maximize Highway Safety Improvement Program Performance.
3. Identifies qualitative considerations in selecting and prioritizing countermeasures (e.g., right-of-way impacts, long-term maintenance, etc.). Other considerations may include bridge/tunnel design, policy and operation, and the use of technologies to prevent BrTS. It may be useful to develop a flow chart or decision matrix to assist practitioners in selecting appropriate countermeasures or mitigation strategies. For instance, if a bridge is at high risk of being struck and a BrTS would have significant operational impacts, then this could indicate the potential to install turnarounds.

Countermeasure Evaluation Process

Countermeasure implementation is typically the end of the project, aside from maintenance, but it is not the end of the roadway safety management process. This chapter focuses on countermeasure evaluation.

1. Describes the importance of evaluating countermeasure effectiveness (post-implementation) to determine if the countermeasure performed as intended. This can help to identify policies, programs, or countermeasures that are working particularly well (and those that are not) as well as situations where certain types of countermeasures perform better or worse (e.g., bridges/tunnels, rural/urban areas, high/low volume roads).
2. Provides an overview of fundamental concepts for evaluating countermeasures, including measures of effectiveness and the data to track before, during, and after implementation. This will include a brief summary and comparison of applicable methods (e.g., simple vs. rigorous before-after studies).
3. Provides quantitative methods for evaluating countermeasures (e.g., simple to rigorous before-after studies). Several resources for performing post-implementation evaluations exist, therefore we do not envision recreating these materials in this chapter. Instead, we plan to provide an overview of concepts and direct readers to available resources for more information. Resources include FHWA’s A Guide to Developing Quality CMFs and FHWA’s Highway Safety Improvement Program (HSIP) Evaluation Guide.
4. Identifies qualitative considerations in evaluating countermeasures (e.g., sample size issues, potential sources of statistical bias, etc.). One common concern is the number of years pre-and post-implementation that would be needed, especially when attempting to detect potentially small changes with relatively limited numbers of BrTS per site. This would also discuss the use of appropriate methods to adjust for regression-to-the-mean and selection bias.

Summary

Conclusions from the research are documented in this final report. The guide targets practitioners. As such, it concludes with an overall summary to capture the key points from each of the prior chapters, focusing on the importance of the order of operations (identify risk factors before selecting countermeasures) and general considerations in mitigating BrTS.

References

This section provides a list of sources cited in the guide.

Resources

Beyond references, there are several tools, reports, guides, and other potential resources that may be of interest to the reader. This chapter includes a summary of other applicable guides and tools that could support implementation of the methods (e.g., benefit-cost analysis and post-implementation evaluation).

Summary

This chapter describes how the guide was developed. Agency and panel members supported the research team in identifying the content that was most important and necessary for the guide. The research team then worked to identify the best way to present the content through multiple iterations and feedback from the panel. These reviews and cycles of feedback resulted in a comprehensive guide that is easy to read and navigate. The research team believes that the guide will provide information for identifying and mitigating the risk of BrTS.