Line 4 of Ottawa’s O-train network has been disrupted by a “switch issue” Saturday, according to OC Transpo, the fourth time this month the line’s experienced problems.

Trains are still running in both directions along the three-station line, but only on one platform, a spokesperson told CBC.

The transit agency posted online that route 105 bus service is also running between the airport and South Keys station.

“Bus route 105 service is always available to the airport. Right now, the only thing a customer would experience is being served on a single platform and potentially a slight delay in Line 4 service,” the spokesperson wrote.

Customers would be informed when things go back to normal by text alerts, social media posts and station announcements, they added.

Service on Line 4 has been suspended on three other occasions this month:

Line 4 was also closed due to staffing shortages in May and June.

The issue also comes as OC Transpo is offering free transit over the weekend, coinciding with Ottawa’s 200th anniversary celebrations.