The TTC says it has successfully tested a new signalling system that will eventually allow it to increase capacity on its busiest subway line by up to 25 per cent.

The transit agency concluded a 13-day test run of the system, known as automatic train control (ATC), on Saturday morning. During that time trains in regular service on the section of Line 1 (Yonge-University-Spadina) between Dupont and Yorkdale stations operated under ATC.

TTC Chief Operating Officer Mike Palmer said the agency is “extremely happy” with how the new system performed.

“It exceeded our expectations, and it bodes well for the future,” he said.

There were some glitches, however. The TTC originally planned to start the in-service testing in mid-September, but unexpected reliability problems pushed back the date.

Once the system went live, 37 malfunctions over the test period caused delays averaging 14.2 minutes per day. But Palmer said the TTC addressed most of the issues and by the final day there were only five minutes worth of delays.

He said the transit agency is on track to have ATC installed on all of Line 1 by 2019, at a cost of $562.3 million.

Parts of the TTC’s signalling infrastructure date back to 1954, when Line 1 first opened. The original signalling is known as a “fixed block” system. In order to keep trains a safe distance apart, the tracks are divided into different sections, or blocks. Only one train at a time can travel through a block, and the blocks both in front and behind it must also be kept clear.

The system limits how close subways can get to each other, and restricts the number of trains the TTC can operate.

By contrast ATC is a “moving block” system, in which trains use radio signals to communicate their speed and location to a computerized control system in real time. The automated system then dictates how fast the trains travel in order to keep them a safe distance apart.

Because the system can more accurately pinpoint the location of trains and closely control their movements, it allows the TTC to run them much closer together.

Once ATC is installed on the entirety of Line 1, the TTC will be able to run trains one minute and 55 seconds apart, instead of the current minimum of two minutes and 30 seconds.

The system is already in place on the new extension of Line 1, which will open on Dec. 17.

ATC in the section between Dupont and Yorkdale has been shut off while work is done at the complex interchange near the TTC’s Wilson Yard. It will be turned back on in the fall of 2018, after that work is finished. Then the entire length of Line 1 between Dupont and Vaughan Metropolitan Centre will operate under ATC.

Palmer said this is the first time in Canada that a new signalling system has been retrofitted onto an operational subway line, which made its installation extremely challenging.

Crews were required to perform work after hours on weekdays, and during weekend subway closures.

“When you build a new line, you have all the time in the world to do your signalling,” Palmer said.

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“We’ve achieved everything we’ve done, including near flawless two weeks of performance, with nighttime closures and weekend testing. And that’s what makes it so phenomenal.”

The TTC also plans to install ATC on Line 2 (Bloor-Danforth) by about 2030, subject to funding availability.