RIDERS’ OPINIONS OF the MBTA plummeted in June, perhaps unsurprisingly, as more than half of the respondents to the T’s regular survey were at least somewhat dissatisfied with the service overall.

The June rating of 2.5 out of 5 is the lowest since that survey began in February 2016, and a striking dip from ratings over the prior 40 months. Previously, the worst month was January 2018, when the rating was 3.01. The best rating so far was August 2017 at 3.5.

“People are unhappy. Service continues to decline,” said Rep. Tommy Vitolo, a Brookline Democrat. “People are frustrated at a deeper level, and it’s going to take more than one or two perfect weeks to get people’s hearts and minds back on board.”

Last month, 53 percent of the 1,261 respondents were at least somewhat dissatisfied with the MBTA, and 19 percent reported they were extremely dissatisfied.

Compare June’s ratings to January 2018, the second-worst month, when only 37 percent of respondents were at least somewhat dissatisfied, and 9 percent were extremely dissatisfied.

The survey was conducted on June 18, a week after a Red Line derailment that knocked out signal systems that controlled miles of track and caused enduring delays on the busiest subway line. That was less than two weeks before fares went up an average of 6 percent, adding to riders’ woes.

Anyone can sign up to take the T’s survey, and those who do will receive a questionnaire every month, according to a T official, who said the data are weighted to match ridership by mode.

There are other data to suggest that riders are fed up. In the weeks after the crash, ridership on the Red Line fell below usual levels.

The MBTA’s performance data dashboard was launched several months after the creation of the MBTA Fiscal and Management Control Board that has overseen the MBTA since the summer of 2015. Gov. Charlie Baker said recently that he regularly consults the data.

“There’s a measure on the T’s website, which I look at every day, which is the on-time performance of all of the commuter rails and all of the rapid transit lines and all of the buses, and I look at it every single day,” Baker said. “And I’m not going to be happy with that until it’s over 90 percent across the board, and we have a lot of work to do to get from here to there.”

In addition to checking in on customer satisfaction, the T uses a variety of different metrics to assess reliability across its various modes. For the subway, the T measures reliability as the percentage of passengers who had to wait less time than the scheduled headway between trains, which is about 4½ minutes during rush hour on the main trunk of the Red Line.

In the 30 days before the crash, reliability on the Red Line had been steadily averaging 92 percent, meaning the vast majority of rush hour passengers had to wait fewer than 4½ minutes for the next Red Line train during rush hour. In the 30 days following the crash, Red Line reliability averaged 75 percent, meaning about a quarter were waiting longer than 4½ minutes. The Red Line countdown clocks that gave estimates about when trains would arrive were knocked out by the crash.

Over the same time periods before and after the crash, Blue Line and Orange Line reliability consistently exceeded 90 percent, while the Green Line slogged along in the low 80s. Reliability on the commuter rail, which runs less frequently than subways or trolleys, has been about 84 percent over that period of time.

Meanwhile, reliability on the buses, which usually need to wade through Metro Boston’s notoriously jammed traffic, is even worse than the Red Line. Bus reliability, which is measured based on how well buses stick to within a few minutes of their schedules, averaged 66 percent in the 30 days prior to June 11 and 69 percent in the 30 days after.

The MBTA handles on average 1.2 million trips per weekday, so riders represent a sizable constituency, and their frustration could galvanize political will to make big changes to the MBTA and the amount of state funding it receives. The Democrats who control the state Legislature are eyeing a big debate in the fall over new revenue sources to finance the MBTA and other transportation priorities.

Perhaps in response to the growing dissatisfaction felt by Bostonian T riders, Boston Mayor Marty Walsh on Monday published an essay about his personal experiences riding the T over the years, the work underway at City Hall to improve transit in Boston, and his demands for more rapid improvements within the MBTA, which is under the control of the governor.

“A world-class city deserves a modern and exceptional transit system, or at least one that is fully operational, reliable, and efficient. That isn’t too much to ask,” Walsh wrote. “With the right investments, Boston and the region can experience the full power of public transit — to connect our city and protect our environment. But we need investment, implementation, and improvement on a faster timeline than we have now.”

In a letter to the MBTA on Wednesday, Walsh called for roughly $9 million in investments from the T in enhanced service to run Red Line trains more frequently during off-peak hours, and run more commuter rail trains on the Fairmount Line, which serves Boston, and on the commuter rail line that serves Quincy and Braintree, according to the State House News Service.

Vitolo said he agrees with Baker’s approach for investing in upgrades to the MBTA over the long-term, but he thinks other changes should happen more quickly – such as giving on-street trolleys and buses priority over cross-street automobiles at traffic signals, creating more bus-only travel lanes, and buying more buses.

Vitolo said Brookline is eager to add more trolley signal prioritization to speed MBTA traffic along and he hopes the town will pursue bus lanes, but the T hasn’t been as responsive as he would like about working on the traffic signals.

“They really do need municipal partners. I’m hopeful that Brookline will be one of them,” Vitolo said.