New Delhi, Dec 6 (UNI) Delhi Metro on Thursday said signaling issue which had affected train services for past two days pertaining to the Blue Line appeared to be a software related problem.
However, the train services are now running normal on the 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.
Signalling issue continued to affect Delhi metro services for the second consecutive day on Thursday on its Blue Line section.
'In view of the signalling issue which surfaced intermittently between 0900 hrs to 1100 hrs on Thursday on Yamuna Bank to Vaishali section of Blue Line affecting punctuality of services on the entire Line, DMRC from 1050 hrs onwards introduced train movement on the entire Blue line, to provide the best possible frequency,' a DMRC spokesperson said.

Train services on a major portion of the Blue Line that is from Dwarka to Noida City Centre are being run in a seamless manner in one go with a frequency of around 4 minutes 30 seconds on automatic mode through central control (OCC).

Train services on a minor portion of the Blue Line that is from Yamuna Bank to Vaishali are being run in an independent loop with a frequency of around 5 minutes 30 seconds through local control (station level).

The signaling team has already carried out the rectification work on the signalling system by noon today.
'However, it is still under observation and the original train operation plan will be reintroduced on the entire Blue Line once the system stabilises,' the spokesperson said.
At present, there are 17 interlocking sections on the Blue Line to maintain train operations through automatic signalling.
There are two systems (one as 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 afternoon, the view and control of the signalling and Automatic Train Control system on Blue Line (Dwarka Sec-21 to Noida City Centre/Vaishali) at Operations Control Centre (OCC) was intermittently getting lost between Karol Bagh and Dwarka section.
As a result, trains were being locally controlled as and when such view loss was happening resulting into intermittent bunching/hold up of trains for brief spells.
Between 1500 to 1530 hrs, the loss of view was for entire Blue line which created bunching on overall Line before being restored again at 1530 hrs.
The issue was resolved at 1623 hrs but intermittent signalling issue resurfaced again around 1900 hrs on Wednesday evening.
'On December 5, there was a technical failure resulting in both the systems at interlocking stations behaving erratically (restarting automatically and switch off) resulting in intermittent disruption of communication with the OCC. As a result, the train services on the Blue Line were available at a frequency of 5-8 minutes,' the spokesperson said.
On the night of December 5th/6th, 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 signalling issue on the remaining interlocking sections between Yamuna Bank to Noida/Vaishali (Yamuna Bank, Anand Vihar and Noida Sec-16) section of the Blue Line have been also rectified today.
In the interim, the software logs have been sent to Germany (Siemens) for online review.
On December 5, 16 trips were cancelled and 20 were delayed on Blue Line (out of 786 planned) due to this issue.
“The signaling issue pertaining to the Blue Line appeared to be a software related problem and M/s Siemens, whose system is operating on this line has been informed about this and log of the erratic behavior of the signaling system has been also sent to their headquarters in Germany for further detailed analysis to help us understand the cause for this fault,' the spokesperson said on Thursday.
The DMRC has adopted a fail-safe system for running of Metro services keeping passenger safety supreme. In the eventuality of any failure on any part of the system, the trains have to follow a set protocol for providing/continuing the services in manual mode with restricted speed in the affected section(s) thereby leading to bunching of trains but ensuring full safety.
'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 spokesperson added.
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