Rising rents are pushing low-income transit-dependent households awy from strong public transit and out to Gateway Cities, where service is less frequent. These residents have just two costly options to get to back to better paying jobs in Boston: driving or taking the commuter rail. Compared to the subway, with its flat fare of $2.25 per ride, riding commuter rail can cost up to $12 each way from Gateway Cities like Fitchburg.

This challenge isn’t particularly unique to Boston. Around the country, large metropolitan economies are flourishing because strong transit allows them to access workers with all the varied skills required in a knowledge economy. Yet funding for these systems hasn’t kept pace with economic growth. This puts public transit agencies in a bind when trying to combat the gentrification forces that accompany centralized growth. Rather than finding ways to make travel more affordable, like the MBTA, these systems are mostly raising fares. Some notable exceptions offer models for Massachusetts policymakers concerned with providing more equitable access to economic opportunity:

1. SFMTA/Muni: Lifeline (San Francisco, CA)

First introduced in 2005, Muni’s Lifeline program is among the longest-running low-income fare programs in the country. San Francisco residents with incomes below 200 percent of the federal poverty line can purchase a $38 card for a month’s worth of unlimited rides on the city’s transit system. This is nearly half off the regular monthly fare of $78. The Bay Area’s Metropolitan Transportation Commission (MTC) provides funding for Lifeline through a combination of dedicated state taxes and federal grants.

Residents can purchase cards through social services organizations by providing proof of income. They must recertify eligibility annually. In 2016, 20,000 of Muni’s 350,000 daily riders (6 percent) utilized Lifeline passes. Lifeline only serves riders living and traveling within the city of San Francisco. The pass has not been integrated with the regional BART system.

2. ORCA LIFT (Seattle, WA)

Starting in March 2015, the ORCA LIFT program allows low-income residents of Seattle and King County to ride public transit at a discounted price. Participants can buy an unlimited monthly pass for $54 or pay $1.50 per ride (normal fares are $2.50 to $2.75). ORCA LIFT cards can be used on multiple transit systems in the region, including the King County Water Taxi, Seattle Streetcar, express buses, and Sound Transit’s light rail.

Similar to Lifeline, individuals can apply for ORCA LIFT passes online, by mail, or at social service organizations, such as foodbanks and health clinics. Residents with household income below 200 percent of poverty ($47,000 for a family of four) are eligible. Funding comes from the King County Transit Authority, which estimates about $4 million in lost fare revenue and $3 million in start-up costs.

As a region-wide program, ORCA LIFT serves a much larger population than most low-income fare programs. A survey of ORCA LIFT cardholders found that 44 percent of riders used transit more frequently than they had before, while 47 percent were taking the same number of trips at a reduced cost, averaging about eight per week. A 2016 assessment of the program reported that 25,000 residents were enrolled countywide and made 3.7 million trips using the card in its first year of availability. There was also a reported improvement in passenger boarding speeds with use of card-based payments as opposed to cash.

3. Transit Assistance Program (Twin Cities, MN)

Beginning this year, Metro Transit in Minneapolis-St. Paul will allow qualifying low-income riders to pay a fare of $1 per ride. Metro Transit piloted this program, known as TAP, in 2015 with just a few hundred riders. Following the system’s first fare increase in 10 years, it is expanding the program to all eligible riders with additional revenue from the fare hike.

The three examples above are limited to light rail and bus systems serving cities rather than commuter rail systems serving larger regions. Examples of low-income fare programs for regional and commuter rail services are harder to come by in the US.

The one model we found is administered by a private transportation management association for its members (as opposed to a public transit agency offering the fare directly to all eligible riders): Palo Alto Transportation Management Association (PATMA) offers free monthly passes on the Caltrain system for employees working at member companies earning less than $50,000 per year. PATMA will also subsidize shared Lyft rides to and from rail stations up to an amount of $150 per month. In order to receive these benefits, eligible workers must jointly file an application with their employer.

For examples of regional transit agencies with low-income fare discounts, we must look beyond the US. In Greater Paris, for instance, residents qualifying for basic income, health, and unemployment benefits can ride the Réseau Express Régional (RER) rail system at a reduced rate under the Tarification Solidarité Transport program. Eligible riders receive 50 to 100 percent discounts on fares, which can run up to 18 euros per trip. As of 2013, 668,000 people were enrolled in the program (participation has increased steadily every year since it began in 2005).