Power being cut on Luas line could have led to fatalities
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A fatal accident could have occurred when a Luas traffic supervisor cut power to a section of the line for maintenance earlier this year without realising that a tram was still operating in the area, an investigation has found.
The oversight resulted in a “flashover” of electricity into the de-energised section when the tram bridged the gap to an electrified part of the line before losing power and coming to a stop.
A report by the Railway Accident Investigation Unit (RAIU) published this week noted that the traffic supervisor did not report the incident until he had left the premises after his shift, and therefore could not undergo a test for drugs or alcohol.
Maintenance personnel had phoned the supervisor at 1.07am on January 5 to enquire about de-energising a section of the line between Suir Road and Kylemore Road for a planned inspection of the Overhead Contact System (OCS).
The traffic supervisor was dealing with another request at the time, and said to the caller: “Just give us a second there, you always ring at awkward times, God bless you.”
When he was ready, the traffic supervisor de-energised the relevant section at 1.09am to allow the scheduled maintenance to commence.
However, he had not looked at a screen displaying the Automatic Vehicle Locating System (AVLS) and therefore did not notice that Tram 4010 was still on the line and due to arrive at the Red Cow depot at 1.33am via the de-energised section.
Maintenance personnel commenced the process of isolating the line between Suir Road and Kylemore Road, putting signage in place and conducting tests to ensure that power had been switched off.
Tram 4010 passed the Suir Road stop at 1.14am, causing a “large flashover” of electricity into the de-energised section when its pantograph bridged the gap that isolated it from the electrified part of the line.
The driver contacted the traffic supervisor, who then realised that he had de-energised the Red Line section without checking if it was clear of trams, the investigation report stated.
He did not immediately report the incident to the on-call officer or log it on the Traffic Event Database (TED). He notified the Luas duty manager at 6.15am — after he had finished his shift at 6am and left the premises.
As a result, the RAIU report noted, no drugs or alcohol tests were carried out. The supervisor, who had worked in the role for 12 years and was a tram driver for four years, no longer holds the position.
The investigation concluded that “safety-critical communications” were partially to blame for the incident, and the conversation between the traffic supervisor and the maintenance worker did not meet the required safety standards.
It also recommended that section insulators be fitted that prevent electric current travelling from an energised part of the line to a de-energised part when the gap is bridged by a tram’s pantograph.
“Under slightly different circumstances, the events may have led to a serious accident with the potential for fatalities or serious injuries due to infrastructure maintenance staff working on the OCS that should not have been open to tram movement,” it warned.