Metro identifies issue with on-board intercoms when certain railcars are paired
Engineers identify cause of problem; Fix to be implemented
Through extensive diagnostic testing, Metro railcar engineers have identified an issue with on-board intercom systems not functioning under certain conditions when 6000-series rail cars are the lead car. Specifically, engineers determined that in circumstances where 6000-series cars are at the front of the train, intercoms in 1000-series or 4000-series cars farther back on the train will not function.
Metro engineers have been working on the issue of reported intercom failures for months in response to passenger and employee reports, as well as a request from the Tri-State Oversight Committee.
"Now that the issue has been identified and verified by engineering staff, we are taking appropriate action to immediately mitigate the situation and resolve it as quickly as possible," said General Manager and CEO Richard Sarles.
After being briefed on the matter yesterday, General Manager and CEO Richard Sarles ordered the following immediate actions:
Railcar intercom signals are passed from one car to the next through a cable called the "train-line," which carries the audio for PA announcements and intercoms, electronic commands to open and close doors, and data for LED signs.
In their analysis of the intercom issues, engineers found that the current level was too low on the 1000-series intercoms for the signal to be recognized when the controlling cab in a 6000-series car. The technical fix involves replacing certain electronic boards within each 6000-series communication control panel. The new electronic boards have different resistors that will allow the 6000-series control panel to recognize the lower-current 1000-series intercoms.
In addition, 4000-series railcars were determined to have an issue communicating with 6000-series railcars at the front of the train due to software in the 4000-series cars.
News release issued at 12:46 pm, June 19, 2013.