Aimed at improving safety along Chicago’s popular Lakefront Trail bordering Lake Michigan, a new flyover structure will miss its scheduled 2018 completion date by at least a year, likely boosting the project’s original $60-million cost. City officials blame the delay on extensive repairs underway on an 80-year-old bascule bridge that carries North Lake Shore Drive over the Chicago River. The bridge will support the third and final segment of the 16-ft-wide flyover, a project begun in 2014 to bypass several hazardous, congested street-level crossings around Chicago’s famed Navy Pier.