Evaluation of Sidewalk Autonomous Delivery Robot Interactions with Pedestrians and Bicyclists

Gehrke, Steven Robert; Russo, Brendan J.; Phair, Christopher D; Smaglik, Edward J. · 2022 · ROSA P / METRANS Transportation Center (Calif.)

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Summary

This study investigates the safety and comfort implications of deploying Sidewalk Autonomous Delivery Robots (SADRs) on shared-use pathways, a practice that has expanded rapidly due to increased demand for contactless deliveries. The research addresses the potential for conflicts between SADRs and human pathway users, such as pedestrians and bicyclists, who share infrastructure originally designed for active travel only. Conducted at Northern Arizona University (NAU), the report comprises two studies: one assessing objective safety through observed interactions and another evaluating perceived comfort through self-reported data. The first study utilized field-recorded video collected over five days at ten high-traffic sites on the NAU campus. Researchers analyzed 187 hours of footage to identify interactions between SADRs and human users, employing Post-Encroachment Time (PET) as a surrogate safety measure to quantify conflict severity. PET was calculated as the time difference between the departure of the first user from a conflict zone and the arrival of the second. Interactions were categorized as dangerous (PET ≤ 1.5 seconds), moderate (1.5 < PET ≤ 3 seconds), or normal (PET > 3 seconds). An ordered logit regression model was used to analyze how conflict-level and site-level characteristics, such as pathway width and intersection presence, influenced severity. The second study assessed perceived comfort by administering a tablet-based survey to an NAU population with experience using automated delivery services. Respondents evaluated their comfort levels using five-point Likert scales in response to stated choice experiments visualizing evasive maneuvers to avoid SADR collisions. The analysis modeled comfort levels as a function of socioeconomic attributes and prior SADR-related experiences. Key findings indicate that moderate and dangerous conflicts cluster near sites with intersecting and narrow pathways lacking clear space delineation. Conflict severity increased when an SADR crossed a human user’s intended trajectory, often prompting evasive action. Regarding perceived comfort, pedestrians generally reported higher comfort levels than bicyclists. However, individuals who had previously altered their paths due to SADRs or reported discomfort were less comfortable with the need to evade robots. Conversely, frequent adopters of autonomous food delivery services demonstrated greater comfort in taking evasive actions. These results provide empirical evidence to inform facility management strategies and regulatory frameworks for the safe integration of SADRs into multimodal transportation networks.

Key finding

Moderate and dangerous SADR-involved conflicts tend to cluster near sites with intersecting and narrow pathways without any delineation of what space human pathway users should occupy, and individuals who have frequently adopted autonomous food delivery services tended to be more comfortable in taking evasive actions.

Methodology

mixed_methods

Sample size: 201

Provenance

The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed. Discovered via bulk_ingest_rosap on 2026-05-23 (6 acquisition events logged).

Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• last mile delivery
• ehmi external hmi