The National Academies

NCHRP 08-163 [Anticipated]

Defining Appropriate Design and Accommodation Thresholds for Active Transportation in a Context-Driven Approach

  Project Data
Source: AASHTO Committee on Active Transportation
Funds: $550,000
Staff Responsibility: Jennifer L. Weeks
Fiscal Year: 2023

This project has been tentatively selected and a project statement (request for proposals) is expected to be available on this website. The problem statement below will be the starting point for a panel of experts to develop the project statement.

A common approach to transportation engineering and design is to set minimum accommodations or guidelines for different modal uses, such as a minimum width for a sidewalk or bike lane or a minimum number of bike parking spaces. The concept also is used at the planning level. For example, some Complete Streets policies specify minimum accommodations for pedestrians and bicycles. However, minimum accommodations are frequently used as the default or preferred width, despite the potential impact of local conditions to support goals such as growth in use of walking, bicycling, and rolling, particularly among all types of users and in areas where greater walking, bicycling, and rolling activity is possible. Research is needed on the design flexibility and the different levels of accommodation recommended for different contexts and roadway types.

The objective of this research is to identify appropriate ranges of accommodation for different modes within a specific road and usage context. Specifically, this research should address (1) how the use of “minimum” accommodations actually service the needs for active transportation, and (2) what alternative approaches and design flexibilities may be appropriate for serving different levels of accommodation for different contexts and roadway types to better serve all road users, with a focus on the design and engineering of roadways and intersections. The research should include an empirical analysis of current designs used by state departments of transportation (DOTs), including the extent to which recommended “minimum” right-of-way guidelines are used or exceeded by state DOTs and the reasons for the decisions that are made. The analysis should similarly address conditions that would warrant restricted accommodation, such as situations with constrained right-of-way.

Possible alternative approaches (or contexts) for a multimodal design application may include:

• Focus on desired performance, such as achieving specific mode share goals;
• Focus on the relative level of service and comfort for different modes within different designs (e.g., what percentage of the population would feel comfortable using the facility walking, bicycling, or rolling) and how that would change with different designs; and
• Focus on a safe-systems approach that includes expectations for safety outcomes. This would explicitly acknowledge that some users are at higher risk.

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