BACKGROUND

A pedestrian can safely cross a street only if one of two conditions is met: either a vehicle comes to a full stop for the pedestrian or an adequate gap in traffic occurs that allows the pedestrian to cross without conflict. To assess such gaps, a pedestrian needs adequate visibility to make the decision.

Currently, evaluating sight distance for crosswalks is typically done from the perspective of a driver’s ability to stop for a pedestrian using stopping sight distance (SSD). However, limited guidance exists on how to evaluate pedestrian decision sight distance. Pedestrian sight distance can be assessed by modifying methodologies from the American Association of State Highway and Transportation Officials’ (AASHTO) A Policy on Geometric Design of Highways and Streets (hereafter the AASHTO Green Book) or Guide for the Development of Bicycle Facilities. However, criteria are not specified to determine the pedestrian crossing time in certain cases, such as Case B3 outlined in the AASHTO Green Book.

Research is needed to establish procedures and methodologies to support state departments of transportation in assessing and ensuring adequate pedestrian decision sight distance during the project development process.

OBJECTIVE

The objective of this project is to develop a framework for assessing sight distance for pedestrian crossings across various roadway contexts and pedestrian types.

Accomplishment of the project objective will require at least the following tasks.

TASKS

Phase I - Planning

Task 1a.  Conduct a literature review of research on pedestrian sight distance and sight lines. This review should include exploring methodologies for assessing pedestrian sight distance, the characteristics and abilities of different pedestrian users (e.g., wheelchair users, children, older pedestrians), pedestrian gap acceptance for crossing roadways of various widths, emerging technologies, and existing or alternative sight distance models applicable to pedestrians. This task may include state and local regulations (e.g., California Daylighting Law), published and unpublished research conducted through the NCHRP and Federal Highway Administration, and other national, international, state, and pooled-fund sponsored research.

Task 1b. Conduct a practice scan and survey of transportation agencies to (1) examine how they incorporate pedestrian sight distance into their project development processes and (2) gather insights on their successes and lessons learned in implementing pedestrian sight distance methodologies. The survey questions and list of potential respondents need to be reviewed and approved by the NCHRP. 

Task 2. Analyze the information gathered in Task 1 to identify gaps and best practices in existing sight distance methodologies as they apply to pedestrians. This task shall include:

• Accommodation of diverse pedestrian characteristics, behaviors, and decision-making processes;
• Various crossing scenarios and traffic control conditions;
• Limitations of current vehicle SSD and intersection sight distance methodologies and assumptions (e.g., pedestrian crossing speed, object height, lateral pedestrian position) when applied to pedestrians;
• Environmental and infrastructural factors that affect pedestrian sight distance;
• Understanding used data, identifying limitations, and exploring data that has not been utilized but could support the new assessment framework;
• Integration of the Safe System Approach principles in pedestrian sight distance assessment; and
• Understanding how design speed, operating speed, posted speed limit, and statutory speed limit will affect the pedestrian sight distance assessment. 

Task 3. Develop a comprehensive research approach based on the findings from the literature review and identified gaps to be executed in Phase II to achieve the project objective. At a minimum, the proposed research approach shall describe the following proposed research activities:

• Identify scenarios in which pedestrian sight distance, sight lines, and pedestrian gap acceptance need to be assessed;
• Validate and adapt existing sight distance methodologies for pedestrian application or develop new methodologies in which gaps exist, incorporating perspectives from pedestrians, drivers, and practitioners; and
• Provide recommendations on variables used for sight distance assessments, such as pedestrian crossing speed, object height, lateral pedestrian position, and pedestrian reaction time, based on user characteristics and roadway contexts.

Task 4. Develop an annotated outline of the draft framework. 

Task 5. Prepare Interim Report No.1, which documents Tasks 1 through 4 and provides an updated work plan for the remainder of the research. The updated work plan must describe the process and rationale for the work proposed for Phase II.

PHASE II – Execution and Deliverables

Task 6. Execute the work plan based on the approved Interim Report No.1.

Task 7. Prepare and submit the draft framework to the NCHRP for review and approval.

Task 8. Prepare draft language in a format and structure specified by AASHTO to conduct pedestrian sight distance assessments, which may be considered by AASHTO for the next update of the Guide for the Planning, Design, and Operation of Pedestrian Facilities (hereafter AASHTO Deliverable). The AASHTO Deliverable will be reviewed and approved by the NCHRP.

Task 9. Present the approved draft AASHTO Deliverable to relevant AASHTO committees for feedback and propose any necessary revisions to the NCHRP. The research team shall anticipate making two in-person presentations to at least two appropriate AASHTO committees, such as the Committee on Design and the Council on Active Transportation. Following the presentations, the research team shall revise the draft framework document and AASHTO Deliverable to incorporate feedback.

Task 10. Prepare the final deliverables. At a minimum, the final deliverables shall include:

• A framework for assessing pedestrian sight distance;
• A final report documenting the entire research effort;
• The AASHTO Deliverable;
• A technical memorandum titled “Implementation of Research Findings and Products”; and
• A presentation slide deck with presenter’s notes summarizing the project and clearly illustrating for the audience how the research can be applied in their organization.

STATUS: Proposals have been received in response to the RFP. The project panel will meet to select a contractor to perform the work.