Name-checking the successful grassroots effort that stopped the Southwest Expressway, City Councilor Charles Yancey told a sometimes raucous crowd of about 175 that he wants to make sure neighborhoods outside JP, notably Mattapan, don't suffer from ills he sees in the massive project. Yancey, who represents District Four, said he'd soon announce a date for a City Council hearing he's sponsoring for an "urgent review of the impacts" on the city's neighborhoods. Yancey was among the many voices at Thursday's construction information meeting at English High School who called the whole effort into question. Transportation officials have struggled at each of the three construction meetings this year to limit discussion to practical questions about carrying out the project. The District 4 councilor wants a series of public hearings on the traffic and environmental impacts of neighborhoods all along Route 203.