Line 4 (O-Train)

Line 4 (French: Ligne 4), also known as the Airport Link (French: Antenne de l'Aéroport), is a diesel light rail line on the O-Train network in Ottawa, Ontario. The line provides a connection between Line 2 (also known as the Trillium Line) at South Keys station, and Ottawa Macdonald–Cartier International Airport. The four-kilometre (2.5 mi) line opened on January 6, 2025.^[1]

Line 4
Line 4 at Airport station
Overview
Other name(s)	Airport Link
Status	Open
Owner	City of Ottawa
Locale	Ottawa, Ontario
Stations	3
Website	Line 4 (OC Transpo)
Service
Type	Diesel light rail
System	O-Train
Rolling stock	Alstom Coradia LINT 41
History
Opened	January 6, 2025; 6 months ago (2025-01-06)
Technical
Line length	4 km (2.5 mi)
Track gauge	1,435 mm (4 ft 8+1⁄2 in) standard gauge
Operating speed	50–80 km/h (31–50 mph)
Route map Line 4 highlighted in blue Show interactive map Legend to Bayview Southeast Transitway to Hurdman South Keys Hunt Club loop to Limebank Airport Parkway Uplands Airport All stations are accessible This diagram: view talk edit Show route diagram

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.^[2] 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.^[3] 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.^[4][5]

Construction of the line began in 2019.^[6] The line was initially considered to be part of the Trillium Line but was given its own number and colour in November 2020.^[7] Construction of Airport station was completed in 2023.^[8]

On January 6, 2025, Line 4 opened, the same day as Line 2's reopening.^[1] Line 4 began with a 5-day service week, expanding to a 6-day service week on January 25,^[9] and finally reached a 7-day service week on March 16.^[10]

Stations

Main article: List of O-Train stations

There are three stations on Line 4, with a connection to the Line 2 at South Keys station.^[4][11]

Station	Notes
South Keys	The eastern terminus; this station provides an interchange with Line 2 in a fare-paid zone and access to the Transitway nearby.
Uplands	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.
Airport	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.

Rolling stock

An Alstom Coradia LINT 41 train at South Keys station

The line uses Alstom Coradia LINT 41 diesel multiple units. Line 4 has 60-metre-long (200 ft) platforms, which are shorter than the 80-metre (260 ft) platforms on Line 2. The difference in length is due to the use of single-car trains instead of two-car vehicles, because of the line's lower projected ridership.^[4][11] The land and station construction at Uplands and Airport station have been reserved and protected for a potential future extension of the platforms, to accommodate 80-metre trains.^[12]