As Toronto impatiently awaits the long-delayed Eglinton Crosstown LRT, Metrolinx continues to press away with the testing and commissioning of the future (or so they say) Line 5.

The transit agency has been offering glimpses behind the scenes of the project in an apparent bid to calm mounting public anger over the undelivered 19-kilometre light rail line, most recently sharing a look into the testing and commissioning process currently underway.

In the first of a two-part blog post shared by Metrolinx on Monday, the transit agency explains that, though major construction works on the line have been completed, "extensive testing and commissioning" must be carried out before passengers can hop on their new $12.58 billion (and climbing) ride.

Testing and commissioning, or T&C, is a key step in preparing the line for revenue service, where crews are able to identify any faults or issues and address them prior to the Crosstown's opening.

Metrolinx describes the work as "an unpredictable phase of any project," which is a bold claim for a major infrastructure project that has been plagued by unpredictability from the start. Lots can go wrong during a T&C phase, as inspectors painstakingly confirm that all elements of the line were properly designed and installed for integration into the broader LRT system.

This process begins long before trains are tested, going all the way back to the start of the line's engineering phase, where the T&C team collaborates to test procedures, proving the line runs as intended.

Metrolinx describes the process like that of purchasing a new car, explaining that "you start with a list of requirements you want your new car to have. The test procedures and associated reports provide evidence that each of the cars you test drive meets those requirements."

That car purchase comparison continues, explaining that after you buy a car and it's been delivered to a dealership, the dealership will verify that "it's the correct model, has the right number of seats, it's the right colour and is in the proper condition."

Similarly, the T&C process after test procedures are in place involves verifying the equipment and the manner it is installed — a form of quality control check before the equipment is powered up.

Metrolinx states that almost 90 per cent of this post-installation checkout process has been completed. This work has been followed up by in-field checks from component manufacturers to make sure everything starts up smoothly for the first time, in a process aptly titled start-up.

Metrolinx once again relies on the car comparison to describe its start-up process — possibly because many would-be Eglinton Crosstown users are commuting via car three years after the line was initially intended to open.

"This is like where a car dealership starts up your new car and takes you around it to show that all the features work properly and explain how they use them."

Once the start-up phase is complete, the next step is called site acceptance testing, which has nothing to do with the public accepting the fact that the site will be undergoing testing for the foreseeable future.

During this stage, crews test out LRT equipment or subsystems under power, but before they are integrated into the broader system.

And, yes. Metrolinx has another automobile comparison to remind you that driving remains a more viable option than their overdue LRT, explaining that site acceptance testing "is equivalent to you starting your new car for the first time. You check the radio, sunroof, windows and start the car to check that there are no unexpected noises or vibrations."

This phase of work is now over two-thirds complete and paves the way for the final steps in the T&C process.

Later phases in the T&C process include the recovery & reliability testing stage, and the almost-at-the-finish-line step of revenue service demonstration before the Crosstown finally enters revenue service.

Metrolinx has still yet to share an official date or even a vague window as to when the Crosstown will carry its first customers.

Construction began in 2011 and was initially scheduled to be completed in 2020. Several delays and ballooning project costs have turned the Line into a political hot potato, and transit riders are just about out of patience with Metrolinx.

After ten years of construction and several delays, Metrolinx CEO Phil Verster announced in September that the line would not open any time soon, stating, "We will announce an opening date once the high-risk testing phase is completed."