The MBTA announced Wednesday it has fully restored all of the signalling systems damaged or destroyed in the June train derailment at JFK/UMass.

The announcement means trains should arrive at stations every four to five minutes during rush hours, the T says.

In addition to restoring the Red Line to its past service levels, the finished work means the T has restored the countdown clocks - which used the signalling system - to all Red Line stations.

The T says it actually finished the repairs over the weekend, but spent several days testing the new system before making a formal announcement.

Investigators have determined a snapped axle sent one car off the rails and into "bungalows" that controlled the routing of trains in and near JFK/UMass, where the Ashmont and Braintree branches come together northbound and split southbound.

With the signals out, the T had to bring in workers to manually flag trains in and out of stations between Broadway and North Quincy - some 57 workers at a time. In the week following the derailment, this reduced service to about one train every ten minutes at rush hour.