MTA Testing its Broken Signals
"The MTA has tested signals on about 90% of the subway system since September," discovering 91 malfunctioning signal timers.
Once the Save Safe Seconds program has completed its testing, "[t]ransit officials plan a program to fix malfunctioning signals. They’ll start on the 1 and Q lines. Then they’ll move on to the D, N and R lines in Brooklyn’s Fourth Ave. line. They also plan to fix signals on the J, M and Z lines on the Williamsburg Bridge and east of Essex St. so they’ll be in shape before the L train shutdown in April."
The article includes more details on the process MTA is using to test the signals, the effect of malfunctioning signals on system performance, and the effect of repaired signals on train speeds.