CEDAR RAPIDS — Life in downtown will change in a fundamental way late this summer when sections of one-way Second Avenue and one-way Third Avenue turn to two-ways, including on the bridges across the Cedar River.As part of the change, the experiment of back-in angle parking on the bridges will end with parking spaces there to revert to the more-conventional, front-in angle parking.The conversion to a two-way street on Second Avenue will extend from Sixth Street SW across the river to First Street SE and on Third Avenue from Sixth Street SW across the river to Third Street SE.At this week’s City Council meeting, Scott Olson, chairman of the council’s Infrastructure Committee, said it was “critical” that the city make sure it had streets properly lined and marked to lessen any confusion for motorists as sections of the busy avenues change to two-way and change back to one-way.Olson and council member Monica Vernon said the conversion is part of the city’s longer-term master plan to change an assortment of one-ways to two-ways.