Literature Reviews

The introduction and potential proliferation of highly automated vehicles (AVs) present the classic challenge of balancing the freedom of private manufacturers to innovate with the government's responsibility to protect public health. AVs raise many public health issues beyond their potential to improve safety, ranging from concerns about more automobile use and less use of healthier alternatives like biking or walking, to concerns that focusing on autonomous vehicles may distract attention and divert funding from efforts to improve mass transit. There are, additionally, issues of access, especially for the poor, disabled, and those in rural environments [1].

As the classic Code of Ethics for Public Health recommends [2], public health advocates can advocate for the rights of individuals and their communities while protecting public health by helping to establish policies and priorities through “processes that ensure an opportunity for input from community members.” Public health thought leaders can ensure that communities have the information they need for informed decisions about whether and how autonomous vehicles will traverse their streets, and they can make sure that manufacturers who test and deploy autonomous vehicles obtain “the community’s consent for their implementation.” Finally, public health leaders can work for the empowerment of the disenfranchised, incorporating and respecting “diverse values, beliefs, and cultures in the community” and collaborating “in ways that build the public’s trust” [2].

Emerging micromobility options such as e-bikes and e-scooters can improve accessibility and connectivity for vulnerable population groups, such as those with physical limitations or without access to a car [1], [2]. Compared to biking or walking, electric micromobility (EMM) vehicles are often more accessible to users with lower interest in or capacity for physical activity, while still providing exercise and outdoor enjoyment [1], [2], [3]. For instance, e-bikes are favored by older adults as a form of physical activity and can encourage micromobility use for distances over 3 miles typically covered by cars [4], [5], [6]. An observational study found that starting to e-bike may increase overall biking frequency among older adults, potentially extending the number of years they are able to bike [4], [5], [6]. Despite being less physically demanding than conventional biking, e-biking offers many of the same cardiovascular benefits [5], [7].
In addition to health benefits from access, physical activity, and outdoor enjoyment, increased EMM vehicle usage has the potential to reduce air pollution from cars by substituting car trips and improving access to public transit. EMM vehicles can address the first-mile-last-mile problem, supporting the use of public transit [8], [9]. They also provide an alternative mode of transportation for short trips, which can help alleviate overcrowding on public transport and support social distancing when necessary [8]. Moreover, EMM vehicles may contribute to noise pollution reduction, which is linked to adverse health effects such as cognitive impairment in children and sleep disturbance [9]. However, studies indicate that not all EMM vehicles have the same environmental health benefits; e-scooters, for instance, may have a negative environmental impact compared to the modes they replace (for example, they may replace pedestrian trips) [9], [10], [11]. Additionally, the collection vehicles used for relocating and charging EMM vehicles in shared vehicle programs can contribute to emissions, particularly in less densely populated areas [9].
Safety remains a primary concern for public health regarding EMM usage, and is discussed in more detail in the section devoted to safety impacts. Cyclists, including e-bike users, are vulnerable to injuries and fatalities from collisions with cars. Electric scooter usage can also result in serious injuries, especially head and limb injuries, exacerbated by low helmet usage [9], [12]. Injuries to pedestrians from e-scooter riders on sidewalks are another significant concern [9]. Providing separate, designated infrastructure for EMM can enhance safety [1].
Future research could include the development of best practices for maximizing public health benefits of micromobility programs, as well as further analysis of the health impacts of different micromobility modes.

Demand-responsive transit and microtransit can benefit public health by improving accessibility. Microtransit services are often more direct or even door-to-door and can serve users with limited mobility. They typically target users whose transportation needs are not met by traditional public transit, including shift workers, low-income individuals, the elderly, disabled, and communities with low levels of fixed-route public transit service [1], [2]. A study on demand-responsive microtransit programs’ return on social investment found that social benefits can outweigh costs by 4 to 6 times, due to their ability to increase access to essential services, foster social inclusion, and improve sustainability [1].
While there are some case studies on microtransit programs, there is limited research on public health impacts. Additional research is needed to understand the extent to which microtransit can meet transportation needs that are not filled by public transit, and how it can best serve different populations and uses, and how it impacts public health. Some of this research is in progress. For example, the "Safety and Public Health Impacts of Microtransit Services" research initiative at the University of Massachusetts Amherst is currently evaluating safety and public health impacts of microtransit services [3].
Finally, on-demand transit/microtransit programs are often meant to improve equitable access, but there is little research on how to design programs to best meet that goal. Survey data from four US cities found that men, younger riders, the highly educated, and transit riders were more likely to be interested in using microtransit. Additional research is needed to understand who on-demand transit/microtransit most frequently serves, and how that impacts public health across demographic groups.

Carsharing may reduce air pollution (and thus provide public health benefits) by complementing public transit use and providing a substitute for private car-ownership. While some people use carsharing to replace public transit, more people increase their public transit and non-motorized trips (like walking and biking) after joining carsharing [1]. A case study of carsharing in Palermo showed a 25 percent reduction in particulate matter (PM10) and 38 percent reduction in carbon dioxide emissions from the shift from private to shared cars [2]. Survey-based estimates have shown that a carshare vehicle tends to replace roughly 15 private vehicles [3], [4].
Carsharing may have also provided public health benefits related to the COVID-19 pandemic. At the beginning of the COVID-19 pandemic public transit was seen as high-risk for exposure, and people with high incomes disproportionately switched from public transit to cars [5], [6], [7]. Carsharing may have provided an alternative for people without a private vehicle, as surveys show that car sharing was preferred over public transit and taxis due to reduced exposure risk [8].
Areas for further research include the impact of carsharing on access to healthcare and other basic needs and services, as well as accessibility of carsharing across groups.

The rise in ride-hail apps and Transportation Network Companies (TNCs) has had mixed effects on public health.
One benefit of TNCs is the enhanced mobility they offer to people who have difficulty driving or navigating public transit, such as seniors and people with disabilities [1], [2]. Access to transportation constitutes a significant obstacle to medical care, particularly for older, lower-income, and non-white patients [3]. Piloted TNC non-emergency transportation initiatives have shown promise in addressing this issue [3]. One study found that ridesharing services make it easier for certain groups—young, low-income, and non-critical patients—to get to the emergency room [4]. Subsidized TNC programs can also help fill gaps in public transit service, providing a way to access medical care and groceries for lower-income travelers [5]. While there is potential for the use of TNC services in transit and special needs ride programs, significant barriers remain. For example, most vehicles cannot accommodate a full wheelchair and require the use of a smartphone app to request a ride [1], [6], [7]. Additionally, drivers may lack training in assisting people with disabilities [8].
Studies have correlated TNC ridesharing availability with decreased fatalities from alcohol-related collisions, particularly if ride subsidy programs are available [9], [10]. However additional research is needed, as there is not a consensus in the literature [11].
Driver health is a significant concern when it comes to TNCs. Health risks include stress, fatigue, musculoskeletal disorders, and urinary disorders [12], and are compounded by job insecurity and the absence of traditional employment benefits [12], [13]. The absence of designated rest areas akin to taxi-stands further exacerbates these challenges [12].

Further research is needed regarding the TNCs’ potential for filling gaps in non-emergency medical transportation, as well as mechanisms to protect driver health and wellbeing.

Researchers have theorized about potential effects of Mobility-as-a-service (MaaS) programs and public health. A study in Transportation Research highlighted health concerns related to possible reductions in active transport like walking and biking, since MaaS products are based on monetizable modes of transport and emphasize door-to-door service [1]. However, another study in Research in Transportation Business & Management argues that MaaS has the potential to incentivize use of active transport [2].

There is a lack of research studying how MaaS models have impacted public health in practice.

A scoping review of public health impacts from on demand food and alcohol delivery published in SSM Population Health found that on-demand delivery services increase geographical access to food but tend to market unhealthy and discretionary foods, and are likely increasing existing health issues and inequities [1]. The review also highlighted concerns over poor age verification processes potentially allowing minors to access alcohol more easily [1].

When electrified, automated heavy-duty trucks can have dramatic reductions in air pollutant emissions that harm human health. A lifecycle analysis study found that the health impact costs of an automated diesel heavy duty truck were twice that of an automated electric heavy-duty truck, and that the automated electric truck caused 18 percent fewer fatalities compared to the automated diesel truck [1].

A 2024 study modeled reductions in damages from air pollution from the introduction of automation and partial electrification in long haul trucking, finding that for long haul routes under 300 miles, electrification reduces air pollution and greenhouse gas damages by 13 percent, and for routes above 300 miles, electrification of only urban segments facilitated by hub-based automation of highway driving reduces damages by 35 percent [2].

To date, much of the research related to health and vehicle automation has focused on passenger vehicles. Additional research is needed to understand potential health impacts of heavy-duty vehicle automation beyond reductions in air pollution, as well as of different types of heavy-duty vehicles and adoption scenarios.

No studies were found looking at the direct impact between connected vehicles (CVs) and public health. However, a great deal of literature has studied how various CV applications, such as eco-driving, traffic signal optimization, and platooning, can reduce carbon dioxide emissions and various pollutants. For example, research indicates that eco-driving can lead to a reduction in fuel consumption by up to 10 percent [1]. Traffic signal optimization through Vehicle-to-Everything (V2X) communication can reduce fuel consumption and emissions by approximately 15 percent [2]. Additionally, platooning can reduce fuel consumption by up to 8 percent for trailing vehicles due to decreased aerodynamic drag [3]. The US Department of Transportation also developed a suite of eco-CV applications, including eco-approach and departure at signalized intersections, eco-traffic signal timing, and eco-lanes, which collectively could reduce carbon dioxide emissions by up to 12 percent [4]. Among these applications, half of them rely on human responses to various messages while the other half relies on automation. Emission reductions are primarily achieved through enhanced situational awareness (e.g., traffic signal status) ahead of time, allowing vehicles or humans to respond in a more eco-friendly way.

Pourrahmani et. al [5] conducted a health impact assessment of connected and autonomous vehicles (CAVs) in the San Francisco Bay Area, finding that road traffic injuries and deaths could be reduced significantly, that emissions could be reduced by CAV-enabled mechanisms like eco-driving, platooning, and engine performance adjustment. However, the study also found that CAV adoption could create negative health effects from reduced physical activity due to mode shift to car travel, in the absence of policies/efforts to mitigate potential health-related risks [5].

Universal Basic Mobility (UBM) may improve access to active transportation modes like bicycling. UBM may also improve health outcomes by increasing accessibility of health care and supportive services, especially among senior populations with limited existing access to mobility. A region’s health is related to its choice in transportation options - policies which provide better access to active transportation modes, such as cycling, or transit, which often requires walking to stops, may improve health outcomes, but the effect is likely to be marginal. At present, health is not a targeted outcome of any UBM programs, and research is needed to clarify the relationship between recipients of UBM and health outcomes.