Literature Reviews

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.

Ride-hail may improve general road safety by providing an alternative to drivers who would otherwise drive inebriated. A study from Great Britain found that the introduction of Uber was associated with a nine percent decrease in severe traffic-related injuries, which the authors hypothesized resulted from fewer drunk-driving trips [1]. Dills and Mulholland (2018) similarly found a decrease in drunk driving incidents, fatal car crashes, and arrests for assault and disorderly conduct with the introduction of Uber [2].

Ride-hail services can also provide an alternative travel mode for users who feel safer taking ride-hail trips than public transit [3]. However, safety concerns can also discourage people from using ride-hail services, particularly women [4].

Relative to taxis, a study in Chicago found that ride-hail trips may be more likely to result in minor injury crashes, though equally likely to result in severe crashes [5]. The authors attributed these crash differences to three potential factors: 1) drivers may be more distracted by the ride-hail app that may abruptly change routes for new passengers, 2) taxi drivers may have more experience than semi-professional ride-hail drivers, and 3) taxi driver regulations may encourage safer driving, such as limited overtime [5]. Job insecurity may explain riskier behavior on the part of ride-hail drivers; Lefcoe et al (2023) found that ride-hail drivers juggling multiple jobs engage in riskier driving behavior than full-time ride-hail and taxi drivers [6].

Ride-hail, also known as Transportation Network Companies (TNC), may alleviate the high cost of car ownership and reduce mobility gaps across socioeconomic divides by providing people with car trips on an as-needed basis. While the socioeconomic characteristics of ride-hail users vary by region, studies often find that users earn higher incomes than the average resident [1]. However, a small portion of all ride-hail users in California suggests frequent users, those who ride more than three times per week, are more likely to not own a car and earn low-income than those who ride less or non-users [2]. Trip data suggest that most ride-hail users request service only for special occasions which averages three trips per month or less instead of relying on ride-hail for regular travel.

In addition to supporting mobility needs among car-free or car-light households, ride-hail may also address issues of racial bias among taxi drivers. Brown [3] found that Black users were more likely to have a taxi trip canceled or a longer wait than white users; ride-hail exhibited no such ethnic/racial gap in service quality. However, important gaps in access to ride-hail services remain. The benefits of ride-hail can only be seen in jurisdictions that allow them and in markets that support them. For instance, users in rural areas with low population densities and destinations spread far apart account for a small minority of riders [4].

Ride-hail drivers, part of the gig economy, are contracted as independent employees and often lack legal protection on labor rights and employment benefits that would be offered to traditional employees [1]. Existing research on ride-hail drivers focuses on the labor conditions of the workforce and understanding the motives behind becoming a ride-hail driver. Research reveals ride-hail drivers attract a diverse group of populations. According to Benner [1], 78 percent of the workforce is people of color and 56 percent are immigrants. Hall [2] concludes drivers are attracted to gig work due to schedule flexibility and additional income outside of their full-time or part-time jobs. There is limited research on the interests and capabilities of current workers in order to develop effective workforce development programs that will empower drivers to take collective action [3]. The current research suggests workforce development tools should also be aimed towards individuals outside the gig workforce, self-employed individuals, or platform workers [3]. While the industry lacks widespread collective action among drivers, many drivers have taken to various strategies to advocate for themselves such as business planning, leveraging platform competition, activism through social media, and using technology to manage the workforce [3].

Transportation Network Companies (TNCs), or ride-hail companies, have the potential to reduce emissions by reducing single-occupancy trip distances through pooled rides and reducing the need for private vehicle ownership. Ride-hail services can also support transit use by providing riders with an option to connect to transit stations, and by complementing transit in times and places it does not operate.

Ride-hail services can, in theory, reduce emissions by linking passengers traveling in similar directions. In practice, however, those benefits are limited. Most trips are not pooled; one study found just ten percent of trips were pooled, and 27 percent involved multiple passengers [1]. Deadheading, or trips made with no passenger in the vehicle (often between where one passenger is dropped off and the next is picked up), contributes to additional emissions. A significant portion of ride-hail trip miles (40 percent, from a study of TNCs in Canada) are deadheading trips. Both pooled and unpooled ride-hail trips emit more pollutants relative to trips taken by single-occupancy vehicles [1].

Ride-hail might also reduce emissions by offering an alternative to private vehicle ownership, or by connecting riders to transit stations. The evidence is mixed regarding the extent to which riders substitute ride-hail for public transit, with studies finding that ride-hail reduces net transit ridership between 14 and 58 percent, depending on the city studied and the type of transit [2], [3]. The more abundant and reliable ride-hail becomes, particularly in urban areas with a rich array of alternative travel modes, the more likely people are to willingly shed their private vehicles [4]. Moreover, electrifying ride-hail can go a long way toward reducing greenhouse gas emissions, particularly electrifying vehicles for full-time ride-hail drivers [1], [5].

Ride-hail use varies both by land use and demographics. In general, people are more likely to use ride hail services in dense, urban areas [1], [2]. Ride-hail users in the United States tend to own fewer cars, and are more likely to use public transit, than the average resident [2]. There are exceptions, notably Los Angeles, where ride hailing is popular in both urban and lower-density neighborhoods [3]. A separate study from California found that people in lower density suburban and rural areas who used ride hail services tended to earn higher incomes; in contrast, urban ride hail users tended to earn lower-incomes [4].

Given that ride-hail trips are more frequent in urban areas, it is unsurprising that places with high rates of ride-hail use also tend to have high rates of street parking occupancy [5]. Ride-hail has the potential to alleviate curb congestion if a sufficient threshold of car trips are replaced. Ride-hail users may select the service specifically to avoid cruising for parking where few curb spots are available, and thus free up a longer-term parking spot [5]. However, those freed up spots may quickly be taken up by drivers who would otherwise have parked elsewhere, parked at a different time, or not made the trip by private vehicle at all. Moreover, ride-hail drivers must compete for curb access when dropping off riders, and thus temporarily congest the curb. Additional research is needed to better understand the impacts of ride-hail on land use and curb congestion.

Several researchers have tried to understand the effects of ride-hailing on transportation system performance related metrics such as vehicle miles traveled (VMT) [1], [2], [3]. Most studies are in agreement that Transportation Network Companies increase VMT and decrease public transit ridership [1], [2], [3], [4]. For example, Wu and MacKenzie (2021) used the 2017 National Household Travel Survey (NHTS) along with causal inference to estimate the effect of ride-hailing services on VMT. They concluded that a net 7.8 million daily VMT or 2.8 billion annual VMT were added nationwide due to ride-hailing services at the time of the 2017 NHTS data collection [1]. Other studies have tried to understand the effect of congestion pricing strategies on ride-hailing ridership [1]. For example, Zheng et al. (2023) estimated the effects of ride-hailing congestion pricing policy on ridership in Chicago and concluded that the policy led to a growth in shared trips and a decline in single trips. Some studies have also tried to understand the effects of ride-hailing on transit and other modes of transportation [1], [2], [3].
Current opportunities for future research include: 1) using more updated data (e.g., 2022 NHTS) to assess the effects of ride-hailing on VMT and travel behavior, as the impact of ride-hailing services changes dynamically, and 2) assessing the impact of ride-hailing services in rural areas and less studied regions of the country, which could provide insights for local and state policies.

States, rather than local governments, have largely assumed responsibility for regulating ride-hail companies. Many states regulate how ride-hail companies can be taxed, and limit cities’ abilities to enact taxes and add fees to ride-hailing operations. Municipalities are thus constrained in their ability to leverage ride-hail services to generate revenues [1]. States vary in the extent to which they limit local control over ride-hail fees and taxes; Lehe et al. [2] examined the U.S. market and created a taxation taxonomy of five regimes: the first was a “hands-off” approach, the second, a tax-free regime to enact prohibit local and state taxes, the third, a state tax only system, fourth, a revenue sharing agreement based on state tax distributed to local jurisdictions, and lastly, a local options where local governments may levy a tax regulated by the state.

Clark and Brown found that repurposed parking spaces to accommodate ride-hail pickup and dropoff and falling parking occupancy reduce on-street and off-street parking occupancy revenues, which are often municipally-owned [3]. A study of New York City area airports found single-digit percentage reduction in parking demand attributable to the introduction of ride-hailing services [4].