A Toronto transit advocacy group has filed a complaint to the city's auditor general, asking her to investigate last summer's Scarborough RT derailment.

On Wednesday, TTCriders said it wanted to know if the issues surrounding the July 2023 Line 3 derailment constituted a breach of public trust. The group added that it is taking this action to ensure this incident never happens again.

The group laid out eight key questions in the complaint, mainly focusing on the information from four independent consultant reports that looked into the SRT derailment.

In February, TTCriders accused the TTC of "quietly" publishing the reports, saying they revealed that the transit agency was warned in early 2023 about issues with how defects were prioritized and how inspections were happening on the SRT.

The group wants the auditor general to investigate some of the following questions: What steps did the TTC take after being informed about the issues, and were the defects addressed prior to the derailment?

TTCriders also wants to know if the TTC cut or curtailed necessary maintenance on the SRT before it derailed and if that contributed to the incident.

"When you add up all of these incidents and pieces of information together, we don't have a lot of trust in whether the TTC did everything it could to keep the RT safe and well-maintained," said Shelagh Pizey-Allen during a news conference on Wednesday.

She added that the group launched the complaint because "there hasn't been enough transparency."

"We're worried about the state of the TTC, and we're asking for the Auditor General of Toronto to investigate," Pizey-Allen said.

MORE: Read the full TTCriders complaint

The SRT was taken out of service after a train car derailed near Ellesmere Station on July 24 and sent five people to the hospital with minor injuries.

The TTC later revealed that defective bolts caused the derailment.

In February, TTC CEO Rick Leary denied TTCriders' claim that the reports were intentionally buried.

"When the report came out, there were elements of the report we wanted to do more due diligence to, and that's what we're doing now," Leary said at the time.

Meanwhile, in response to the complaint, the TTC reiterated that the derailment was unrelated to maintenance.

"Safety of our customers and our employees is the TTC's paramount concern. We will only ever run service when it safe to do so," the statement read.

"Maintenance and state of good repair are integral to ensuring [the] safety of our system and are always kept current."

The TTC noted that the consultant reports will be presented and debated at the April 11 board meeting.

Councillor Jamal Myers, the chair of the TTC board, said he is looking forward to the meeting, where he can ask authors of the reports.

"The TTC Board, the City of Toronto, and TTC take the safety and reliability of public transit seriously which is why the 2024 budget for TTC included an increase in funding towards state-of-good repair as well as a fully funded Scarborough RT Busway. Collectively, we remain committed to providing a safe, comfortable, and reliable service to TTC customers, which keeps our City moving," Myers said in a statement.

With files from Codi Wilson