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Suggested Citation:"Chapter 1: Background." National Academies of Sciences, Engineering, and Medicine. 2018. Assessing Interactions Between Access Management Treatments and Multimodal Users. Washington, DC: The National Academies Press. doi: 10.17226/25344.
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Page 1
Page 2
Suggested Citation:"Chapter 1: Background." National Academies of Sciences, Engineering, and Medicine. 2018. Assessing Interactions Between Access Management Treatments and Multimodal Users. Washington, DC: The National Academies Press. doi: 10.17226/25344.
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Page 2
Page 3
Suggested Citation:"Chapter 1: Background." National Academies of Sciences, Engineering, and Medicine. 2018. Assessing Interactions Between Access Management Treatments and Multimodal Users. Washington, DC: The National Academies Press. doi: 10.17226/25344.
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Page 3
Page 4
Suggested Citation:"Chapter 1: Background." National Academies of Sciences, Engineering, and Medicine. 2018. Assessing Interactions Between Access Management Treatments and Multimodal Users. Washington, DC: The National Academies Press. doi: 10.17226/25344.
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Page 4

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1 C H A P T E R 1 : B A C K G R O U N D Background The roadway system must accommodate many types of users—bicycles, passenger cars, pedestrians, transit, and trucks. Increasingly, stakeholders are recognizing that there should be an appropriate balance among the various modes from a design and operations standpoint. There is increasing recognition that the location and design of access to and from roadways impacts all transportation modes. As the emphasis on considering all users grows, there is a need to better understand the effect of access management techniques and treatments on multimodal operations and safety. In addition, suburban and urban land uses continually redevelop, and access management planning for retrofitting corridors should consider the multimodal travel needs, as well as the need to upgrade motorized vehicle performance. Past studies have shown that arterial roadway characteristics such as turning movements, unsignalized and signalized access density, median type, turn lanes, sidewalks, bike lanes, and bus turnouts can affect corridor operations or safety. Studies have also shown that effective access management treatments reduce and manage conflict points along roadways, leading to reductions in delays and crashes. However, there is limited understanding of the effects of access management treatments on multimodal travel operations and safety, particularly for treatments used in combination. Thus, there is a need for research to improve the level of understanding of treatment effect. To obtain this understanding, quantitative relationships need to be developed that could be used to assess the effectiveness of access management techniques based on (but not limited to): average travel speed, travel time reliability, crash frequency, crash severity, or capacity preservation. In addition, practitioners would benefit from having effective guidance on how to weigh, evaluate, and understand the effects and tradeoffs when implementing access management techniques in a multimodal corridor. Research Objective The objective of this research was to identify and determine unknown relationship definitions between access management techniques and the various users or travel modes along multimodal corridors. The deliverable is a final report that documents the conduct of the research and includes quantitative information that can be: (1) incorporated into publications such as A Policy on the Geometric Design of Streets and Highways (AASHTO Green Book) and the Highway Capacity Manual (HCM), and (2) used in the development of simulation software. The end product is intended to be useable by practitioners both for technical analysis and to support their efforts to explain technical findings to non-transportation professionals and public stakeholders. Research Scope This section defines the scope of the research project in terms of the facility types and travel modes that were the focus of study. It also establishes some terms used throughout this report.

2 Facility Types Access management (AM) techniques can be implemented at the systems, corridor, or site level. A site in this research effort is considered to be a street segment or intersection. A corridor is an arterial street consisting of several segments (and the intersections that bound the segments). A system includes multiple adjacent or intersecting corridors. The project scope is limited to the development of techniques suitable for application to sites and corridors in urban areas. Travel Modes There are many AM techniques being used in practice. Most of these techniques have been devised to improve motorized vehicle performance, to manage their conflicts, or both. These techniques are referred to herein as vehicle-conflict-motivated AM techniques. Research that has been conducted for various vehicle-conflict-motivated AM techniques typically focus on the technique’s effect on motorized vehicle safety and operation. These studies often exclude consideration of the effect of the technique on the performance of other modes. As a result, there is relatively little information describing the effect of vehicle-conflict-motivated AM techniques on the performance of the pedestrian, bicycle, transit, and truck modes. To this end, the focus of this project was on the effect of vehicle-conflict-motivated AM techniques on the performance of the pedestrian, bicycle, transit, and truck modes. These four travel modes are referred to herein as multimodal users or non-auto roadway users. Direct Effect of a Technique The research that has been conducted to date has focused on quantifying the “direct” effect of the AM technique (i.e., the effect when a specific technique is implemented in isolation of other techniques). Very little research has been conducted to quantify how the direct effect may be altered when a second or third technique is also implemented at the same time. Nevertheless, the focus of this project was on the direct effect of a technique on the pedestrian, bicycle, transit, and truck modes given the aforementioned paucity of information for these travel modes. The need for supplemental information that describes the combined effect of multiple techniques on these four modes is identified in Chapter 5 as a topic of future research. Technique or Treatment A review of the AM literature indicates frequent use of the phrases “access management technique” and “access management treatment.” The term “treatment” is typically used to describe a planned change in the roadway’s geometric design or traffic control elements. The term “technique” is typically used in a broader sense to include treatments as well as planned changes in AM policies, regulations, or strategies. This convention is retained in this report. Given that the focus of this report is on changes to roadway design and traffic control elements, the terms technique and treatment are used interchangeably herein. Performance Relationship One piece of information that is often needed by practitioners when considering the implementation of an AM technique is the technique’s “performance relationship.” This relationship is defined herein as an analytic model of the effect of an AM technique on the performance of a specific travel mode. A performance relationship can be either qualitative or quantitative (although quantitative relationships are generally more informative). In addition, a performance relationship can be a rule-of-thumb, a constant,

3 an equation, or a procedure used to predict the effect of an AM technique’s implementation on the change in performance of one travel mode. Finally, a performance relationship can stand alone serving one specific purpose (e.g., a constant that defines the percent reduction in crash frequency due to a specific change in driveway design) or it can be embodied in a predictive methodology that estimates site or corridor performance as a function of one or more variables (e.g., a procedure for predicting the effect of turning vehicle speed and volume on bicycle safety). Research Plan The research plan consisted of two phases. During the first phase, information was gathered and used to develop an analytical framework for the development of performance relationships that describe the effect of an AM technique on pedestrian, bicycle, transit, or truck travel. Also, a data collection plan was developed to facilitate calibration of performance relationships. The information used to develop this framework was gathered from a review of the literature and a survey of transportation agencies. During the second phase of the project, performance relationships were developed for two AM techniques. Each relationship was calibrated, tested, and refined. Then, they were incorporated in the Guide for the Analysis of Multimodal Corridor Access Management. Achievement of the research objective required the completion of 12 work tasks. Tasks 1 through 6 are associated with the first phase of the project. Tasks 7 through 11 are associated with the second phase of the project. These work tasks are identified in the following list.  Task 1: Amplified Research Plan  Task 2: Literature Review  Task 3: Identify Interactions Between Access Management Techniques and Travel Modes  Task 4: Survey of Agency Needs to Quantify Modal Access Management Enhancements to Corridors  Task 5: Assess Data and Information Needs  Task 6: Submit Interim Report  Task 7: Corridor Selection and Data Collection  Task 8: Development of Quantitative Measurement Tools  Task 9: Development of Multimodal Access Management Best Practices and Identification of Further Research Needs  Task 10: Development of the Guide for the Analysis of Multimodal Corridor Access Management  Task 11: Prepare Final Report  Task 12: Access Management Multimodal Analysis Implementation Support The key work activities associated with this project are identified in the following list:  Reviewed the literature on AM techniques and their potential effects on roadway users (see Chapter 2 and Appendix A);  Surveyed transportation agency staff, consultants, and university researchers on the need for additional knowledge of the impacts of AM techniques on various travel modes (see Chapter 2 and Appendix B);  Developed a process for prioritizing the AM techniques to be studied as part of the research (see Chapter 3 and Appendix C);  Designed the data collection and analysis plan (i.e., study design) for the high-priority AM techniques (see Chapter 3 and Appendix E)

4  Using the collected data, developed tools for predicting the performance of high-priority AM techniques (see Chapter 4 and Appendix G);  Documented the findings of the research (see Chapter 4); and  Documented the conclusions and suggestions for future research (see Chapter 5). A separate document produced by this research, Guide for the Analysis of Multimodal Corridor Access Management, identifies more than 70 access management strategies and documents the known quantitative and qualitative performance relationships between these strategies and the motor vehicle, pedestrian, bicycle, bus, and truck modes. The Guide also incorporates the new findings documented within this research effort.

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TRB’s National Cooperative Highway Research Program (NCHRP) Web-Only Document 256: Assessing Interactions Between Access Management Treatments and Multimodal Users describes operational and safety relationships between access management techniques and the automobile, pedestrian, bicycle, public transit, and truck modes. This contractor's report may help assist in the selection of alternative access management techniques based on the safety and operation performance of each affected travel mode.The roadway system must accommodate many types of users—bicyclists, passenger cars, pedestrians, transit, and trucks. This report examines the interactions between multimodal operations and access management techniques and treatments, and the trade-off decisions that are necessary.

NCHRP Research Report 900: Guide for the Analysis of Multimodal Corridor Access Management accompanies this report.

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