They voted to have the City Manager investigate the issue, and start discussions with the DCR and MassDOT.

"ORDERED: That the City Manager is directed to work with the Law Department and the Traffic, Parking and Transportation Department to investigate how to ban turns on red Citywide; and be it further ORDERED: That the City Manager is directed to contact the Massachusetts Department of Conservation and Recreation, and the Massachusetts Department of Transportation, to begin discussions of banning turns on red movements on roadways in Cambridge controlled by those state entities; and be it further ORDERED: That the City Manager be and hereby is requested to report back to the City Council on this matter in a timely manner."

I'm not sure if this text reflects the amendments they passed.