Subway commuters, take note: a portion of Line 1 is scheduled to close earlier than usual on Wednesday and Thursday evenings so crews can do signal upgrades.

On Apr. 24 and 25, Line 1 between Bloor -Yonge station and St. Andrew station will close at 11 p.m.

Shuttle buses "will run frequently and stop outside each affected station," a news release from the Toronto Transit Commission said.

Wheel-Trans will provide service to each affected station for those who need it, the release said.

Wellesley station will also close at 11 p.m., but all other affected stations will remain open for fare sales and to provide access to surface routes.

The closures are necessary so more of the automatic train control (ATC) signalling system can be installed. According to the TTC release, portions of the current signalling system date back to the 1950s, "when the subway first opened."

The new system will improve capacity on Line 1, the release said.

The new system is currently installed on about 40 per cent of the line, between Vaughan Metropolitan Centre and Dupont stations, and will extend to St. Patrick station in the spring.

"While the TTC does most subway maintenance at the conclusion of service each night, it continues to require weekend and early weeknight closures to complete critical infrastructure and ATC upgrades," the release said.