The Monongahela Incline could reopen as early as Wednesday, pending state inspection, Pittsburgh Regional Transit officials said

The 156-year-old funicular unexpectedly stopped Thursday night, leaving two passengers stuck about 80 feet from the stations. Pittsburgh public safety personnel rescued the trapped passengers.

The incline has remained closed since the incident.

Pittsburgh Regional Transit’s maintenance and engineering teams have since been troubleshooting the issues, officials said.

They determined moisture in an emergency stop button caused the shutdown.

The transit authority has since conducted dozens of successful test trips over the past 12 hours. A Pennsylvania Department of Labor & Industry inspection is scheduled for Wednesday morning.

PRT officials said service could resume later in the day Wednesday if the incline passes inspection.

“While we’re happy to see this current issue resolved, we will continue assessing the long-term reliability of the system and determine what additional steps may be necessary to ensure safe, reliable service moving forward,” PRT Chief Maintenance Officer Don Rivetti said in a written statement.

In November, 27 people got stuck on the incline when both cars stopped shortly after leaving the stations.

Dating to 1870, the Monongahela Incline is the oldest continuously operating railway system of its kind in the nation. According to PRT, it transports more than half a million riders each year.