Testing and commissioning (T&C) is an important phase that every transit project must go through to ensure it is safe and reliable for customers.

In the first part of this two-part series, we went through the T&C basics and broke down the first two steps. Now we’ll explain the final phases of T&C.

The T&C process is being carried out by Crosslinx Transit Solutions, the project constructor and was created in line with worldwide industry practices for other major infrastructure projects.

System Integration Testing

After the team has completed site acceptance testing (explained in part one) on two or more subsystems that are required to work together, they can perform the first phase of system integration testing (SIT).

This is where Crosslinx crews take two or more subsystems and operate them together through various scenarios to verify that the two systems are passing the required information between them and that any cause-and-effect requirements are occurring properly. 

An example would be integrating a fire alarm with an escalator. Upon the fire alarm activating, the escalator must come to a gradual stop to provide people with a safe way to exit.

Integrated System Testing

When the T&C team has performed enough system integration tests, they will conduct the first in a series of integrated system tests. 

The integrated system tests are important as they confirm that there are no unexpected conflicts between the integrations of various subsystems that may not normally be expected to affect each other.

When there are subsystems that are critical to safety, relevant fail-safe testing is performed at this stage to validate that the system functions safely as expected in failure scenarios.

Recovery & Reliability Testing

The last stage of testing is reliability and recovery testing. 

While the two types of tests are different, they are both normally performed during this phase so that the outcomes are not influenced by a subsystem that may not be operating correctly.

Recovery testing is performing scenarios that would be required to bring the system back to normal during and after a serious service-affecting event.

For example, if a train becomes disabled and needs to be towed back to the maintenance facility, recovery testing helps the team verify that all the correct subsystems are powered by the emergency system, and that it can stay on for the required amount of time.

Reliability testing is performing scenarios that could occur during revenue service where there are redundant systems that take over to ensure there’s no detriment to revenue service.

An example of reliability testing is where an antenna on the vital network goes offline, but coverage is still available for the system due to the overlap of other antennas.

Revenue Service Demonstration

After the T&C process is substantially complete and no major issues are remaining, the team will move into the phase of demonstrating the rail service capabilities for the project.

TTC, Crosslinx Transit Solutions and Metrolinx will review the performance, identifying all areas of concern and work together to resolve any outstanding issues.

Testing & commissioning continues

As a key part of bringing any new transit project safely online, testing & commissioning is critical.

Crews are working every day, testing everything from trains and station announcements to outdoor switches, and even the air quality inside the tunnels, to make sure everything is working correctly and safely for when customers first step aboard.

Keep an eye on this channel, as well as the Metrolinx and Eglinton Crosstown LRT project social media channels for regular progress posts.