‘‘As some have noted, including (his wife) Amy, I am not a patient man,’’ Emanuel said after he was sworn in as mayor a year ago. ‘‘When it comes to improving our schools, I will not be a patient mayor.’’

The issue of teacher evaluations has only been on the table in Chicago for a few months, and Emanuel acknowledged this week that his swift push for change could be a factor in why his relationship with the union has been so contentious. In other big cities, a more patient approach has led to success in finding agreement with reluctant teachers.

The deal reached Wednesday in Boston will allow administrators to rely more heavily on student achievement in teacher evaluations and remove from the classroom those receiving poor evaluations within 30 days. That contract came after 400 hours of contract negotiations that spanned more than 50 separate sessions over two years.

‘‘Change is hard and is often hard-fought. But we should make special note that through all the tough negotiations, neither side let their frustrations spill onto the students of the Boston Public Schools,’’ said Mayor Thomas Menino. ‘‘I tell you, this is a contract that’s great for our students, works for our teachers and it’s fair to our taxpayers.’’

Slowing down the timeline for implementing the evaluations has also led to success elsewhere.

In Cleveland, the city’s school district made its deal with teachers by agreeing to a loose framework for the new evaluations that would take four years to implement. The school system and the union spent a year constructing the evaluations, and then began a two-year pilot process that will not incorporate student test scores. That will come for the first time in the 2013-14 school year.

‘‘This is complex work and it takes time to build it thoughtfully and carefully,’’ said Cleveland schools CEO Eric Gordon. ‘‘It really has been a joint commitment in the beginning. We all believe that this is the right (approach).’’

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Associated Press writers Christina Hoag in Los Angeles and Rodrique Ngowi in Boston contributed to this report.

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