Ride-Pooling & Carbon: Who Actually Cuts Emissions?

The Problem

Is ride-pooling actually green? The answer is: it depends entirely on who you ask.

The environmental case for pooled rides sounds airtight: instead of five people driving five cars, put them in one van. Vehicle kilometres drop. Emissions drop. Problem solved.

The problem is that not everyone switching to a pooled service was previously driving a car. A substantial share of pooled-ride users in cities like Mexico City were previously taking the metro — one of the most emissions-efficient modes of transport that exists. When those riders switch to a shared van, they move from a lower-emission mode to a higher-emission one. The van is more efficient than five cars, but it is far less efficient than a full subway train.

Most previous research on ride-pooling's carbon impact either analyses operational data comparing pooling versus solo ride-hailing, or runs hypothetical mode-shift simulations. None had combined individual user-level data with actual trip records to segment users and calculate segment-specific emissions. This paper does exactly that.

The transport modes from which users switch to ride-pooling, and the differences in CO₂ reduction capacity across users, are crucial to exploring the environmental benefits of ride-pooling.

Using data from Jetty in Mexico City — over 100,000 trips and a detailed survey of 1,118 riders — the researchers applied Latent Class Cluster Analysis to identify five distinct user profiles, then calculated each profile's net emissions impact.

The Five Classes

Not all pooled-ride users are the same — and the differences define the carbon outcome

Click any class to see who they are and what drives their emissions result.

Class 1 · 34% of users

Van-Preferred Travelers ↓ Reduces CO₂

The largest class and one of the two that actually reduces emissions. Young, highly educated full-time workers who prefer Jetty vans, walk or bike to stops, and make shorter trips. They replace a balanced mix of car trips and public transit, so the van genuinely displaces some private car use. Their van preference gives them the lowest per-trip emissions of any Jetty mode. Average CO₂ reduction: −37.9 kg/user across all trips at 0% empty km.

Class 2 · 19% of users

Travel Time-Conscious Travelers ↑ Increases CO₂

Every user in this class rides Jetty buses, and 82% cite travel time savings as their primary reason. The problem is what they are switching from: mostly combinations of paratransit and formal public transit. Their alternative modes had lower emissions per passenger-kilometre than Jetty buses. Male-dominated, working-age, with rigid schedules — they value time, not the environment. Average CO₂ increase: +15.5 kg/user.

Class 3 · 17% of users

Low-freq High-morning-trip Travelers ↑ Increases CO₂

The least frequent riders — 62% use Jetty less than once a month. Almost exclusively morning commuters: 88% make over 92% of their Jetty trips before noon. They replace public transit combinations (paratransit and metro) with buses, resulting in a modest emission increase. Balanced gender split, lower full-time employment than other classes. Their infrequency limits total impact, but the direction is still upward. Average CO₂ increase: +7.1 kg/user.

Class 4 · 17% of users

Frequent Ride-pooling Travelers ↑↑ Highest CO₂ increase per user

The most troubling class environmentally — and the one with the clearest social explanation. This class is 81% women, predominantly without cars or driving licences, and its defining characteristic is that members use Jetty specifically because public transit in Mexico City is unsafe. They replaced public transit and paratransit (53% replaced metro + paratransit combinations). Their shift from low-emission modes to Jetty buses drives the largest per-user emission increase: +45.5 kg/user. The researchers explicitly note this is a direct consequence of Mexico City transit insecurity — these users are not choosing Jetty for comfort, but to escape harassment.

Class 5 · 12% of users

Formerly Private Travelers ↓↓ Largest per-user CO₂ reduction

The carbon star of the study — despite being just 12% of users. This high-income, car-owning segment was predominantly driving private vehicles before joining Jetty. Their switch generates the largest per-user emission reduction: −63.1 kg/user at 0% empty km. They ride frequently, and combining high trip frequency with a large emission differential per trip amplifies the impact enormously. The policy implication is clear: every car-to-Jetty conversion in this class is a significant climate win.

Why Vehicle Choice Matters

The emission factor spectrum explains the paradox

One of the paper's key contributions is a careful calculation of CO₂ emission factors for every relevant mode in grams per passenger-kilometre. The range is enormous — from the Mexico City Metro at under 1 g/p·km to a solo taxi at nearly 384 g/p·km. Where a Jetty vehicle sits on this spectrum determines whether it increases or decreases emissions for any given user.

CO₂ Emission Factors by Mode (g per passenger-km) — Source: Zhi et al. 2025, Tables A.3–A.4

Metro (subway)

0.94

Suburban Train

0.97

Metrobus (BRT)

11.4

Jetty Van ★

35.8

Combi / Microbus

34–35

Jetty Caddy ★

67.5

Jetty Bus ★

95.7

Jetty Taxi ★

114.7

Car driver/passenger

191

Taxi / Uber

384

★ = Jetty modes. The Jetty bus (95.7 g/p·km) is better than a private car (191) but roughly 100× worse than the metro (0.94). That gap explains everything.

This spectrum explains the paradox at the heart of the paper. The same Jetty bus reduces emissions when it replaces a private car, and increases them when it replaces a metro trip. The user's previous mode is everything.

Interactive Tool

Model the CO₂ impact yourself

Emission outcomes depend on user class, vehicle type, and the rate of empty kilometres — the distance vehicles travel without passengers between routes. Adjust below to explore the range mirroring Table 6 in the paper.

CO₂ Impact Calculator

FROM TABLE 6 · ZHI ET AL. 2025 · UNIT: ×10³ G CO₂ PER USER ACROSS ALL TRIPS

User class

Empty km rate (deadheading)

—

Select options above

Choose a user class and empty-km scenario to see the estimated per-user CO₂ impact.

The Hardest Finding

The public transit security failure has a measurable carbon cost

Class 4 — the Frequent Ride-pooling Travelers — generates the most CO₂ increase per user. But it also has the clearest and most troubling explanation. It is 81% women, predominantly without cars or driving licences, and its defining characteristic is that members use Jetty specifically because public transit in Mexico City is unsafe.

These users were not choosing between a car and a van. They were choosing between a bus they fear and a slightly safer service they can afford. The greener option — the metro — was not a real option, because riding it means exposure to theft and sexual harassment so severe that Mexico City metro is considered one of the most dangerous urban rail systems in the world.

The insecurity of public transport has a direct impact on CO₂ emissions — and the people paying both costs are overwhelmingly women.

The implication is direct: the environmental sustainability of pooled rides cannot be separated from the social sustainability of public transit. Making metro systems safer for women is not just a human rights issue — it is, measurably, a climate intervention.

Key Variables

Income and empty kilometres are the system's two decisive levers

Users with personal income above 30,000 MXN/month reduced total CO₂ by 5.73 million grams across their trips — despite representing only 19% of the sample. Why? Because high-income users disproportionately replace private car trips (43% would have driven if Jetty were unavailable). From a climate policy perspective, the most carbon-valuable pooled-ride users are wealthy car owners choosing to leave their car at home. Low-income users, by contrast, tend to replace public transit, so their adoption increases net emissions. This creates an uncomfortable but important equity-environment tension that policymakers must confront directly.

Deadheading refers to distance driven by Jetty vehicles without passengers — drivers taking vehicles from home to route start points, or vehicles waiting between peak periods. The paper models four scenarios: 0%, 10%, 20%, and 30% empty-km rates. At 0%, the system reduces emissions by 8.53 million grams. At 20%, this flips to an increase of 2.04 million grams. At 30%, the net increase reaches 7.33 million grams. Efficient depot placement and route scheduling are therefore not just operational improvements — they are direct climate interventions.

Jetty vans (35.8 g/p·km) achieve better climate outcomes than Jetty buses (95.7 g/p·km), even though buses carry more passengers. The reason is modal substitution, not vehicle efficiency. Van users more often replaced car and taxi trips; bus users more often replaced metro and paratransit. A van carrying 8 people who would otherwise have driven is a climate win. A bus carrying 15 people who would otherwise have taken the metro is a climate loss. The finding from the first paper in this series on VKT is mirrored here in the emissions analysis: vans win on both traffic and carbon metrics, not because of their size, but because of who rides them.

Looking at individuals rather than class averages: 40% of Jetty users reduce CO₂ emissions with their pooled trips, and 60% increase them. Of those who reduce emissions, 57% are from Class 1. The distribution is heavily skewed: some users reduce by up to 900 kg, while others increase by up to 330 kg. This individual-level heterogeneity — especially within Class 5 — suggests that even within user segments there is significant variation driven by the specific mode being replaced. One-size-fits-all policies will be insufficient.

Policy Implications

Five targeted actions — one per user class

01

Class 1 — Expand van coverage and invest in pedestrian and bike-friendly egress

Van-Preferred Travelers are the largest class and the biggest aggregate CO₂ reducers. Grow this class: expand van fleet coverage for routes under 21.7 km, invest in cycling infrastructure near van stops, and create corporate ride-pooling subsidy programmes targeting this educated full-time-employed demographic.

02

Class 2 — Dedicated bus lanes and off-peak incentives

Travel Time-Conscious users chose Jetty buses for time savings. Improve bus operational efficiency through dedicated lanes and real-time scheduling to enhance the time advantage while reducing emissions intensity. Off-peak fare discounts could shift trips away from congested, high-emission periods.

03

Class 4 — Make public transit safe. This is a climate intervention, not only a social one.

Women who use Jetty to escape harassment are driving the largest per-user emission increases — not because of anything wrong with their choices, but because the formal transit system has failed to provide basic safety. Emergency response systems, improved lighting, security staff at stations, and dedicated carriages are simultaneously a gender equity intervention and a carbon reduction strategy.

04

Class 5 — Target car owners with premium incentives and carbon credit programmes

Formerly Private Travelers deliver the highest per-user carbon reduction. Personalised carbon credit programmes, employer subsidies, and guaranteed seat-booking services targeting this high-income car-owning demographic can amplify the aggregate climate benefit enormously. Every car-to-Jetty conversion in this class is worth far more than a transit-to-Jetty conversion.

05

All classes — Minimise deadheading through smart fleet management

At 20% empty kilometres, the entire system flips from net climate benefit to net climate harm. Route optimisation, strategic depot placement near route endpoints, and dynamic repositioning algorithms are the highest-leverage operational decisions an operator can make for climate outcomes.

Ride-pooling can cut carbon — or raise it. It depends entirely on who is riding.