A crowded field of local and state agencies will collaborate on yet another plan for redesigning Morrissey Boulevard, the crumbling and frequently flooded highway that divides Dorchester neighborhoods from the Boston Harbor waterfront. On Thursday, the City of Boston, Boston Planning & Development Agency (BPDA), Massachusetts Department of Transportation (MassDOT), Executive Office of Energy and Environmental Affairs (EEA), and Department of Conservation and Recreation (DCR) announced a new joint planning effort to “evaluate and recommend transportation and infrastructure improvements” with goals that include improved mobility for pedestrians, bikes, transit riders, and motorists, and a more resilient waterfront that can better protect low-lying Dorchester neighborhoods from storm surges and rising tides.