Line 4 (O-Train)
Line 4, also known as the Airport Line, is a diesel light rail line on the O-Train network in Ottawa, Ontario. The line provides a connection between Line 2 at South Keys station, and Ottawa Macdonald–Cartier International Airport. The line opened on January 6, 2025.
History
Initial plans for expansions of the Trillium Line in 2013 considered an expansion to Ottawa Macdonald–Cartier International Airport. However, these plans were discarded due to lack of funding and a focus on attracting ridership from the south of Ottawa. In 2016, the Ontario provincial government committed $1 billion to O-Train expansion, providing half the required funding for an extension to the airport, with an additional station at the EY Centre. Additional funding was acquired for the Airport Link through federal funding and the airport authority, who constructed the airport station for approximately $20 million, with $6.4 million from the federal government.Construction of the line began in 2019. The line was initially considered to be part of the Trillium Line but was given its own number and colour in November 2020. Construction of Airport station was completed in 2023.
On January 6, 2025, Line 4 opened, the same day as Line 2's reopening. Line 4 began with a 5-day service week, expanding to a 6-day service week on January 25, and finally reached a 7-day service week on March 16.
Stations
There are three stations on Line 4, with a connection to the Line 2 at South Keys station.| Station | Notes |
| The eastern terminus; this station provides an interchange with Line 2 in a fare-paid zone and access to the Transitway nearby. | |
| Located east of Uplands Drive next to the EY Centre and features two platforms. It is the location of the only passing loop on the line. | |
| The western terminus; it is located at the Ottawa Macdonald–Cartier International Airport and built into the renovated and expanded terminal at the departures level. |