Denver RTD's Zero Fare for Better Air program reduced greenhouse gas emissions

The Denver Regional Transportation District's (Denver RTD) final evaluation report to the Colorado Energy Office outlines the overall impacts of the agency's two-month Zero Fare for Better Air (ZFBA) initiative. The final report shows an increase in customer boardings and estimates a reduction of approximately 9 million vehicle miles traveled during July and August. Additionally, estimates show more than 6 million pounds of greenhouse gases were eliminated when individuals opted to use public transit instead of a single occupancy vehicle.

To assess the environmental impact of the 2023 ZFBA initiative, Denver RTD partnered with the Regional Air Quality Council (RAQC). RAQC is the lead air quality planning agency for the nine-county Denver Metro/North Front Range Ozone Nonattainment Area. RAQC’s analysis utilized the Greenhouse Gases, Regulated Emissions and Energy use in Transportation (GREET) model to estimate the initiative’s overall impact on the region’s air quality.

According to RAQC, the ZFBA initiative helped reduce both ozone precursors, volatile organic compounds and nitrogen oxides, which in the presence of heat and sunlight, combine to form invisible but harmful ground-level ozone.

"When public transit is easy to use, people use it more,” said Mike Silverstein, RAQC executive director. “Increased public transit use also reduces the top two sources of ground-level ozone precursors in the Front Range: Emissions from cars and light trucks and fuel production by the oil and gas industry to fill those tanks. Denver RTD’s Zero Fare for Better Air initiative helps reduce both our fossil fuel use and the demand for its production, making a positive impact on our local air quality during peak ozone season.”

During the zero-fare initiative, Denver RTD conducted a comprehensive intercept survey of individuals using the system to better understand ridership decisions, commuting trends and customer behaviors. The survey directly engaged Denver RTD’s customers onboard buses and trains and at key stops and stations. The intercept survey was distributed across the entire Denver Metro region to align responses with ridership numbers. One of the survey questions asked what mode of transportation a customer would have used had they not taken Denver RTD for that specific trip. Responses to the question were used as an input into the GREET model.

Based on the GREET model, which used ridership data and survey responses among other variables as inputs, the RAQC estimates Denver RTD’s zero-fare initiative led to a total reduction of 9 million vehicle miles traveled, 2,583 pounds of volatile organic compounds, 2,385 pounds of nitrogen oxides and 6 million pounds of greenhouse gases, equating to a daily reduction of 145,393 vehicle miles traveled and 99,383 pounds of greenhouse gases. For context, the Denver Regional Council of Governments estimated the daily vehicle miles traveled in the Denver Metro region were approximately 83 million in 2022.

“The second year of the Zero Fare for Better Air initiative affirmed extensive support for public transit. Moreover, staff garnered valuable lessons related to travel patterns, security resource deployment and customer preferences for mobility options,” said Denver RTD General Manager and CEO Debra A. Johnson. “I once again extend my thanks to the Colorado Energy Office, whose assistance and partnership made this second year possible.”

The ZFBA initiative also experienced a 10 percent increase in the overall number of boardings on bus, rail and paratransit services. When compared with the same period last year, the agency had an additional 1.1 million customer boardings on Denver RTD’s system during July and August 2023. Boardings during the two-month initiative reflect the largest number of customers Denver RTD has had on its system since the COVID-19 pandemic impacted ridership in March 2020.

In comparison with the same period last year, mode-specific highlights include:

• Bus saw a 16 percent increase in boardings
• Commuter rail experienced a 14 percent increase in boardings
• Ridership on the A Line increased 14 percent year-over-year and accounted for nearly 75 percent of commuter rail’s boardings during July and August
• Light rail saw a 13 percent decrease in boardings, much of which can be attributed to months-long planned maintenance projects that impacted the E, H and R lines
• Paratransit saw a 50 percent increase in boardings

Major findings from the customer intercept survey include:

• 74 percent of respondents said the zero-fare initiative influenced their decision to use Denver RTD’s services on the day they were surveyed
• 84 percent of respondents said cost savings was an important factor regarding their decision to use Denver RTD’s services
• 85 percent of respondents indicated the environmental benefits of the initiative influenced their decision to take a bus or train
• 72 percent of respondents planned to increase their usage of Denver RTD’s services during the initiative
• 33 percent of respondents said the primary purpose of their trip was work related
• 23 percent of respondents indicated they would have driven themselves if they were not using Denver RTD’s services

The collaborative, statewide initiative was funded through a grant program created by Colorado Senate Bill 22-180 in an effort to reduce ground-level ozone during peak periods by increasing the community’s use of public transit. In 2023, Denver RTD expanded its zero-fare offering from one month to two, to align with Colorado’s highest ozone months of July and August and leveraged available state funding appropriated for the Ozone Season Transit Grant Program.

Denver RTD’s ZFBA 2023 Evaluation Report is publicly available on Denver RTD's website.