Senate President Therese Murray and other Legislative leaders vowed today to use political muscle to fight the powerful police union and limit details at some construction sites.

The proposal to use lower paid civilian flagmen in some work zones could, according to Murray’s office, help save $100 million over 20 years, which is $5 million annually. The police details have long been cash cows for officers. Lawmakers revealed few specifics, but said it would be studied over the next several weeks. They said the intent is not to eliminate all police details, but to spell out instances where they don't need to be used, such as dead ends or on less congested streets.

Murray outlined the plan and a number of other transportation reforms at a press conference today in the Senate Reading Room as she was flanked by dozens of lawmakers, including Governor Deval Patrick and House Speaker Salvatore F. DiMasi.

The proposals also include a plan to streamline construction projects, a crack down on retirement and pension plans at the MBTA, and a measure that would force the Massachusetts Turnpike Authority to explore getting rid of more manual toll collectors by adopting electronic tolling systems.

But the police detail changes, which would allow lower paid civilian flagmen to direct traffic, are expected to be the most controversial. Critics of the police details have long argued the state and local municipalities should be allowed to save money by using flagmen, especially on less congested streets.

The guidelines could be in place within months.