The Navy Pier Flyover, a bike and pedestrian path that was finally expected to fully open at the end of 2019, has pushed back its completion date by a few months into spring 2020.

The century-old bridges and outdated infrastructure has made repairs take much longer than expected, said the Chicago Department of Transportation (CDOT). City engineers and workers have had their challenges, especially having to cut through two bridge houses built in 1937.

“Safety is our paramount concern as we continue work on the Navy Pier Flyover, which has been a complex project both in terms of construction and staging,” CDOT said in a statement.

The agency expected to work on the eastern sidewalk, but made the decision to focus on structural repairs on the western side of the path for safety reasons. Work on the center bay is planned to begin in November, when that wraps up at the end of the year construction on the east bay of the bridge will start. The structural repairs to the bridge will continue until the fall of 2020.

The flyover, which first began construction in 2014, replaces a previously unsafe section of the Lakefront Trail where bikers and pedestrians were close to busy vehicle traffic. This summer the 16-foot wide path partially closed twice for weeks at a time so crews could connect sections and start work on the final third phase.

The work that remains in phase three involves retrofitting the Lake Shore Drive Bridge with a cantilever structure that will widen that trail and remove any possible bottleneck areas plus the rehab of a movable bascule bridge.

While construction continues, a single lane will be open for cyclists and pedestrians. When the project is finished, the 2,160-foot flyover will carry visitors across Illinois Street and Grand Avenue on the Lakefront Trail (about 100,00 per day on summer weekends, according to the city).