Ross Wilson wears a sense of relief that’s currently in fashion inside City Hall and the Boston Teachers Union on Mt. Vernon St.

The 36-year-old assistant superintendent was a member of Superintendent Carol Johnson’s negotiation team that worked to hammer out a teachers’ contract after more than two years of tense talks. Last Thursday, a day after a resolution was announced, Wilson sat in his office, recalling how it came to fruition.

“Two nights ago, we knew, when we were going into it, we felt we were in a good place,” he said. “Because we worked all weekend, this past weekend, and we did all the thinking about it, and we really felt like, ‘Geez, we’re so close.’”

One constant during the various ups and downs of the negotiations was the lack of food. Wilson said the two camps once had an all-night session at the Parkman House on Beacon Hill, finishing at seven or eight o’clock in the morning. “We’re going into this thing, thinking we’re hopefully getting something done, it could be a late night, but nobody had provisions,” he said of the last negotiating session. “I should have packed Spam and my sleeping bag.”

The agreement revamps a performance evaluations system, using language from state regulations instead of the city’s proposed regulations, includes a 12 percent salary increase over six years, and calls for lower class sizes and the hiring of support staff such as paraprofessionals.

The contract, retroactive to Aug. 2010, is expected to cost $160 million over the six years, largely because of the salary increases.

Wilson, who works in the department of teacher development and advancement, has a special focus: “We have this new performance evaluation system which absolutely does speed up the timelines for ensuring we have the best teacher in every classroom and moving out teachers who are not effective,” he said.

The current set-up is a binary system, based on a few observations and deeming a teacher as “meets standards” or “does not meet standards.” But it doesn’t spell out timelines, Wilson said, and it’s wrought with “procedural elements that really has the evaluator focused more on dates and procedures than on giving good valuable feedback to the teachers and supporting growth.”

The new system has four different categories: unsatisfactory, needs improvement, proficient, and exemplary. “We can tell who’s ‘exemplary’; we can tell who is ‘needs improvement’ and needs support,” Wilson said. “So not just wrapping up everybody in these two ratings, but really identifying who our workforce is and how to support them.”

The system will also include multiple observations of teachers over the course of the school year. Every educator also self-assesses about how they’re doing and sets two goals linked to student learning and professional learning.

While some school districts in other states say students should factor into a significant percentage of a teacher’s evaluation, Massachusetts does not have that requirement. Wilson said he supports the Bay State’s stance. “I’m much more supportive of what the regulations state, which is that the evaluator has their professional judgment and they look at a wide variety of evidence, evidence towards those four standards and two goals,” Wilson said. “And student data is involved through the student learning goal, but it does not trump the judgment of the evaluator.”

Asked about Johnson’s description of some aspects of the state’s performance evaluation model as “cumbersome,” Wilson said the department believes they have developed enough tools for evaluators and teachers to handle the more procedural elements of the contract language.

“We cannot have long time lines and durations for educators when they’re ineffective,” Wilson said, noting that he is the parent of three children. “And I think that’s a mutual interest for the Boston Teachers Union and BPS.”

Seniority rules – about which people get laid off first – remain unchanged, Wilson said, since that is in the purview of State House lawmakers.

The proposed contract has drawn fire from critics, including City Councillor At-Large John Connolly, chair of the council’s education committee. In an opinion piece published in this week’s Reporter, Connolly called the contract “status quo” and a “hollow accomplishment.”

Students needed a longer school day, he wrote, and the contract “failed to add a single additional minute of learning time to a school day which rates as one of the shortest in the nation.”

For his part, Wilson seems happy to have his weeknights and weekends back. “It was like 2:30, 3 in the morning,” he said, remembering the last night of negotiations. “And I think we all just shook hands and said congratulations or good work. It was really gratifying. These are the people we’ve all known for a long time and you could put us in a room and we all get along with each other. And everyone’s doing their job. And so it felt really good to not be sitting right across from one another, in intense bargaining. It felt really good just saying, ‘Hey, good work, we’re glad we’re done.’”