Commuters faced problems travelling in the Delhi Metro's Blue Line Thursday morning as train services were affected on the entire stretch owing to a signalling issue apparently due to a "software problem", a day after the corridor faced a similar technical snag twice.
The DMRC also said that "16 trips were cancelled and 20 were delayed on the Blue Line (out of 786 planned)" due to the signalling issue Wednesday.
The Blue Line connects Dwarka to Noida and Vaishali and is one of the busiest segments of the Delhi Metro network. Vaishali section branches off from Yamuna Bank, an intersection station.
"There was some signalling issue which intermittently surfaced on the Yamuna Bank to Vaishali section of the Blue Line between 9 AM to 11 AM, affecting punctuality of services on the entire Blue Line," a senior DMRC official said.
The DMRC from 10:50 AM onwards introduced temporary arrangement for train services till the problem was solved.
He said a temporary arrangement for train services was made till the problem is solved.
"Train services between Dwarka and Noida were run in one go with a frequency of around 4 minutes and 30 seconds on an automatic mode through central control, i.e., Operations Control Centre," the official said.
The regular frequency of trains on Dwarka-Noida line is 2 minutes and 30 seconds, he added.
"Services between Yamuna Bank and Vaishali stations were being run in an independent loop with a frequency of around 5 minutes and 30 seconds through local control (at station level)," he said.
Several commuters took to Twitter and complained of delays. Many said that their trains were stuck for as long as 30 minutes.
"The metro was standing at Nirman Vihar for around 30 mins today morning and the Noida metro was also moving very slow," tweeted Priya Singh, a commuter.
Another commuter tweeted, "...I used to reach my destination BVP college from Vaishali metro in 60 minutes. Today I was struck in between many times and even didn't reach half my destination in 60 minutes."
Executive Director, Corporate Communications, Anuj Dayal said, "The signalling issue pertaining to the Blue Line appeared to be a software related problem and the company, Siemens, whose system is operating on this line, has been informed about this."
"The log of the erratic behaviour of the signalling system has been also sent to Siemens headquarters in Germany for further detailed analysis to help understand the cause of this fault," he said.
A senior official said the signalling team had carried out the rectification work on the signalling system by noon. However, it was under observation until the rectification was don for the entire Blue Line.
"The train services are now running normal on entire Blue Line with a frequency of 3 minutes 30 seconds on Dwarka-Noida section and 5 minutes 30 seconds on Yamuna Bank-Vaishali section," the official said.
Train services were affected twice on the Blue Line Wednesday due to signalling issues in different sections of the corridor.
The first technical snag had occurred around 3 pm. The issue was resolved at 4:23 pm and train services were started as per schedule. However, the snag recurred around 7 pm at another section.
At present, there are 17 interlocking sections on the Blue Line to maintain train operations through automatic signalling.
There are two systems (one as a back-up) simultaneously operating at all these interlocking stations which manage the signalling communication of Metro trains with the Operations Control Centre (OCC).
On Wednesday, there was a "technical failure" resulting in both the systems at interlocking stations behaving erratically (restarting automatically and switching off) resulting in intermittent disruption of communication with the OCC, he said.
"On the night of December 5-6, the signalling team had been able to completely rectify the signalling issue on the five interlocking sections from Barakhambha to Dwarka Sec 21 section," the official said.
