A major extension is in the works for Toronto's shortest subway line, the Line 4 Sheppard, and Metrolinx is asking the public to help shape the line's future path.

Opened in 2002, the truncated Sheppard line has been criticized as a 'stubway,' and a pet project of former Toronto (and North York) mayor Mel Lastman.

Running just 5.5 kilometres with only five stations, the line has never lived up to ridership projections, mostly because it doesn't really go anywhere.

However, the line could get a second wind with a long-discussed extension for the Sheppard subway now just around the corner.

Plans to expand Line 4 were resurrected in 2023, and Metrolinx is now working on the extension's Initial Business Case (IBC).

As part of the IBC process, the transit agency has released four concept routings that offer a glimpse at how the Sheppard line could look decades into the future.

Concept 1 contemplates an eastern extension of the line that would see a mixed-grade subway constructed from the current terminus at Don Mills to a new station currently under construction at Sheppard/McCowan as part of the Scarborough Subway Extension.

This concept would add six new stops to the network, with connections to the upcoming Scarborough line and a link to Agincourt GO at a new Line 4 station planned at Sheppard and Kennedy.

Metrolinx

Concept 2A would extend the line in both directions, with a mixed-grade subway extension from the current western terminus at Sheppard-Yonge to the western leg of Line 1 at Sheppard West Station, and east from the Don Mills terminus to Sheppard/McCowan on the Scarborough Line.

This concept would add eight new stops to the existing line, including new connections to two subway lines and a GO station.

Metrolinx

Concept 2B follows a similar approach as 2A, adding eight stops with a mixed-grade extension to the east and west, but with the eastern terminus moved slightly south to the upcoming Scarborough Centre Station on the Line 2 Scarborough extension.

Metrolinx

Concept 3 focuses on an easterly extension and would add nine stops to Line 4 with a mixed-grade subway from Don Mills to Sheppard/Morningside. While this plan would be the biggest win for a transit-starved Scarborough, extending further east than any other rapid transit line in the city, it and Concept 1 both lack key connections to the west.

Metrolinx

The planning process for the new subway extension is still in its early stages.

Metrolinx's latest report on the proposal states that the plan is currently in the first of a six-stage process, where concepts for the line's expansion are being analyzed. If approved and funding is secured, a second stage will involve further consultation, detailed community impacts, and environmental studies.

In the meantime, Metrolinx is seeking public feedback on the extension and will hold two public meetings on June 18 and June 20, where locals can weigh in on the concepts.

Those unable to attend are encouraged to take an online survey that will remain open until July 25.