The launch of Namma Metro’s Yellow Line has been delayed yet again, with sources familiar with the development indicating that the line is now likely to open in late July or even August.

Deputy Chief Minister D K Shivakumar had earlier announced a target of May 2025 for the operational launch of the Yellow Line.

The 19.15-km stretch connecting RV Road to Bommasandra has been held up primarily due to a shortage of trains. In late April, the Bangalore Metro Rail Corporation Limited (BMRCL) submitted documentation to the Commissioner of Metro Railway Safety (Southern Circle) to begin the statutory safety inspection process.

However, a key component — the Independent Safety Assessment (ISA) certification for the train signalling system — remains pending. A senior BMRCL official revealed that glitches in the test datasets have delayed the issuance of this certification.

According to the official, BMRCL has conducted all required statutory tests on the new rolling stock, including multi-train trials. During a review of the datasets, Siemens India Ltd-Siemens AG, the signalling contractor for the Yellow Line, identified software-related issues that need to be corrected.

The official explained that the software manages all critical aspects of train operation — including acceleration, braking, speed control, routing, and train spacing. Therefore, any malfunction in the software must be corrected, tested in real-world conditions, and validated before further progress can be made.

The official also noted that metro systems adhere to Safety Integrity Level 4, the highest standard for safety-related systems. Any failure or glitch prompts the system to switch to a safe mode by default.

The process of resolving these issues has taken longer than expected. The official pointed out that Siemens cannot move forward with seeking the independent assessor’s clearance until all safety tests are completed and verified. While efforts are being made to speed up the process, the situation is currently beyond BMRCL’s direct control.

Siemens has reportedly assured that the ISA certification will be ready by the end of June. Only after receiving this certification can BMRCL formally request the Commissioner of Metro Railway Safety to conduct the final inspection. Based on this timeline, the inspection is likely to take place in July.

On a positive note, BMRCL has completed all static tests on the third train, which arrived in Bengaluru on May 14. Mainline testing of this train is expected to begin in the coming days, the official confirmed.

Train deliveries are also expected to pick up pace. Titagarh Rail Systems Limited (TRSL), the supplier for the Yellow Line, is expected to deliver the fourth train by the end of July. The official mentioned that TRSL has started manufacturing carbody shells in-house under the supervision of engineers from CRRC, the main contractor. With production now stabilised, TRSL is expected to deliver one train per month after July.

The first train, along with the carbody shells for the second and third trains, were all imported from China.