Case Study

Mask-Wearing Compliance on Buses


The COVID-19 pandemic caused many employees who would typically commute to work to begin working from home. However, scores of essential workers continued to rely on public transit in order to get to work throughout the pandemic. We partnered with the City of Durham Transportation Department and City’s Recovery and Renewal Task Force to develop strategies to promote passenger safety and increase rider mask-wearing on buses. 


Although research has not pointed to a direct relationship between the spread of COVID-19 and the use of public transportation, risks still exist due to the inherently social nature of public transit and reliance on individual rider compliance with public health measures such as wearing a face mask. 

Research strongly supports the need to maintain safety measures such as mask compliance and proper ventilation on transit throughout the pandemic. Other recommendations to enhance safety on transit include creating waiting areas that allow for proper social distancing, encouraging feedback from transit employees and riders, utilizing rear entrances for boarding, and supporting transit planning groups with their pandemic response.

Transit systems must strive for passenger safety in order to continue serving essential workers who rely on transit for their work commutes.


1) Adams et. al. (2020)
2)  National Association of City Transportation Officials (2020)

Prototyping and Exploration

We tested the impact of in-person social regulation and message framing to increase mask-wearing compliance on GoDurham buses.  Because compliance was fairly high to begin with, a high-touch intervention was required. The City of Durham hired Wellness Ambassadors to share positive reinforcements and safety reminders to onboarding passengers as well as those waiting at bus stops. The Ambassadors shared the following messages with riders:

  • Reciprocity-based - “Thank you for wearing a mask over the mouth and the nose.”
  • Social norms-based - “Most people are doing their part to keep us all safe.”
  • Identifiable victims-based - “I care because it’s keeping me safe too.”

Experimental Design

The hypothesis we tested was that the presence of Wellness Ambassadors who provided health and safety reminders to passengers would increase bus riders’ compliance with mask wearing. We assigned six GoDurham routes into treatment and control conditions. The treatment routes had Ambassadors present during both morning and afternoon peak times throughout a two-week testing period. On-board CCTV footage was used to assess the presence or absence of passenger masks.


We found that the presence of Wellness Ambassadors on the treatment routes was associated with a 5% increased mask-wearing compliance compared to control routes. 

Figure 1. Mask-wearing on Durham buses increased in the treatment group with the presence of Wellness Ambassadors.

Various limitations of this study are important to consider. Since we could not randomize individual riders into a treatment and control condition and instead had to randomize bus routes, the characteristics of riders could have varied between routes. Additionally, it wasn’t possible to track individual riders throughout the study although it is likely that some of the same riders were present multiple times in the data. This study was conducted for a limited, two-week period which makes it difficult to determine if the impact of Wellness Ambassadors would remain the same in the long term.

Why It Matters

It is important to identify key strategies in increasing the public’s compliance with public health measures, such as mask-wearing and to work with local governments to design messages that are effective and palatable. These findings suggest that when encouraging mask compliance, in-person prompts to comply are an effective strategy. This insight is relevant in transportation and beyond.