OAKLAND — With ridership at record highs and constant delays on the aging system, satisfaction with BART is at a 20-year low, according to the transit agency, which presented its biannual customer survey results Wednesday.

The agency’s overall satisfaction rating plummeted 15 percentage points in the past four years, from 84 percent of customers responding they were either “very satisfied” or “somewhat satisfied” in 2012, compared with 69 percent in 2016. And, over the past two years, the number of people saying they would “definitely” or “probably” recommend BART to a friend dropped 4 percentage points, while the proportion of people who said BART was a “good value for the money” also fell 4 percentage points.

Rebecca Saltzman, the president of BART’s governing board, said the results were far from surprising.

“Even for myself, it’s been frustrating,” she said. “This past week, every single day I’ve taken BART, there has been a delay.”

2016 was a difficult year for BART, which got off to a tumultuous start with a fatal shooting on a BART train and the subsequent revelation that most of the cameras in the train cars are fakes. That was followed by several weeks of equipment problems and mysteriously disabled trains because of electrical surging issues near the West Oakland station in late February and between the North Concord and Pittsburg/Bay Point stations in mid-March.

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Then, in April, the power went out on a new test car, which ran off the tracks at the Hayward maintenance facility and drove into a sand bank, revealing possible problems with the power system in BART’s new fleet.

Driving passenger dissatisfaction is the screeching noise of BART wheels grating against the tracks, the lack of available seats and constant breakdowns of elevators at stations, according to a staff report. And, as might be expected, riders who were forced to stand during at least part of their ride gave lower satisfaction ratings than those who found a seat.

At the same time, the number of people piling onto BART trains each day has steadily increased, putting more pressure on infrastructure that is aging and more susceptible to failure, two factors BART staffers said in a report were the primary cause of the lower satisfaction ratings.

But, Saltzman said, there is light at the end of the tunnel. A new fleet of train cars is expected to begin rolling out later this year and are supposed to ease crowding and improve riders’ experience. The recently passed $3.5 billion bond measure is dedicated to increasing train reliability, and investments in the system’s elevators and escalators, which are prone to breakdowns, should help relieve customers’ ire at stations. The agency is also planning to remake the wheels on BART’s train cars, which is expected to reduce the familiar ear-splitting screech.

“Fortunately, we have a very good plan for how we will increase capacity and improve service in the next few years,” Saltzman said. “Unfortunately, most of that work hasn’t happened yet.”