I don't recall riding the Alford St. Bridge but do ride North Washington St across the Charlestown Bridge. The bridge is a little dicey with the metal surface, high curbs and slippery sidewalks. You can walk across the Charles River Dam just west of the bridge. Once across the bridge, jog east a block and take Main St. to go north to Alford St.
There is talk about adding bike paths to cross the river with the train tracks out of North Station but for now there is the beautiful crossing under the Zakim on the north side connecting to Paul Revere Park.boston charlestown Everett.jpg