Nearly one out of every ten San Francisco Municipal Railway bus and light-rail riders are not paying fares, according to a new agency study to be presented to the Muni board on Tuesday.

Fare evasion costs the agency, which struggled to close a $129 million budget deficit this summer, an estimated $19 million each year, according to the study.

Muni averages about 700,000 riders each weekday.

“As essential as Muni is to San Franciscans, there is a widespread perception that many of its customers do not pay their fare to ride the system,” the study said.

The perception “has a negative impact” on the agency, “reducing public confidence in the system and making it more difficult to increase public funding and implement new initiatives for service improvements,” it said.

The study, conducted April 30 through July 23 aboard more than 1,100 bus and streetcar trips throughout the city, found at least 9.5 percent of riders didn’t have proper proof of payment. Cable cars were not part of the study.

Most of those surveyed — 68 percent–had either no fare receipt or transfer, or an invalid one. Another 8 percent jumped off the vehicle, or remained at the stop without boarding, as soon as they saw a fare inspector.

Fare evasion happens more often at night, and is more common on buses than on light-rail vehicles, the study found.

Violations can result in a $75 fine.

The agency has recently redeployed some of its fare inspectors from light-rail vehicles to certain bus lines that have been identified as having particular problems with fare evasion, according to SFMTA spokesman Judson True.

Saturation inspections by Muni inspectors and San Francisco police, begun in late July on buses and light-rail vehicles, yielded 1,900 citations, according to the agency.

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