Acting Mayor Kim Janey is hoping a free ride will give her a lift to the polls.

Janey on Monday announced a three-month pilot program that eliminates fares on the Route 28 bus that connects the neighborhoods of Mattapan, Dorchester and Roxbury. The city is paying for the program with $500,000.

The free bus program starts on Sunday, Aug. 29 and runs through Monday, Nov. 29, overlapping with the Sept. 14 preliminary election and the Nov. 2 election. The preliminary will narrow the field of five major candidates to two.

One mayoral rival, City Councillor Michelle Wu, who has pushed for fare-free public transit since 2018, said more than “one free route through Election Day” is needed.

The busy bus route, which carries 13,000 people each weekday, runs along a key economic corridor that includes Grove Hall and Nubian Square, from the Ruggles MBTA Station on the Orange Line, to Mattapan Square, which is the terminus of the Ashmont trolley. Two-thirds of Route 28 riders are classified as low-income residents.

“If there was more money we could obviously extend longer, but we wanted to do at least three months so we could really measure the impact,” said Janey, who took a Route 28 bus from her Roxbury home to a Monday press conference in Mattapan Square to announce the free bus service.

A reporter noted that the MBTA’s statewide governing board controls the public transit system and asked how much power a mayor has to make changes. “Well, one thing I just did as mayor is I’ve offered a free bus,” quipped Janey, the City Council president who became acting mayor in March after Marty Walsh left for the Biden administration. “Did you hear that news?”

Janey, who is running for a full four-year mayoral term, added: “I would love to see free buses all throughout the city of Boston. There’s no secret there. I’ve been advocating for that. We thought it was really important to start with the 28 bus route, given that it has the largest share of riders, given that it is a major economic corridor.”

City transportation officials and the MBTA plan to jointly manage the program, and collect metrics such as impact on travel time, reliability, rider experiences and ridership levels.

“We look forward to evaluating it and learning more about its impacts on ridership and the transit network,” the MBTA’s general manager, Steve Poftak, said in a statement.

Councillor Wu, who joined other elected officials at Monday’s press conference, called the pilot a “small step,” and noted that the city of Lawrence, inspired by her advocacy for fare-free transit, launched a two-year pilot. The city recently extended it for another two years.

“Three months is a blink of an eye and for us to really affect people’s plans, and small businesses, and the potential for economic opportunity to take off, you need to have a little more predictability,” she said.

Route 28 has seen past efforts to improve rider experiences. In 2009, state transportation officials pressed for an express busway, to speed up the time spent on rides. But officials withdrew the proposal, dubbed “28X,” after community opponents complained that it would have eliminated parking spaces and ripped up trees along the avenue.

State Rep. Russell Holmes, a Mattapan Democrat who supported the 28X project at the time, said he’s hopeful that the three-month free bus pilot this fall, with students taking the bus and people returning to offices, the MBTA and city officials will gather a “very good sense” of ridership.

“The 28 is an ideal place to begin, where we think we have the most need,” he said.