Railroad crews and heavy equipment including tie inserters and extractors have been moving along the Newburyport/Rockport Commuter Rail Line between Lynn and Salem.
They were working this past weekend on the rail section behind Essex Street and on Tuesday were at work near the Swampscott Train Station.
In addition to replacing railroad ties — to improve reliability and performance — crews are conducting routine maintenance at train stations.
"We expect work on the entire project to be completed in early October," said Rhiannon D'Angelo, a spokeswoman for the Massachusetts Bay Commuter Rail (MBCR) Company. "Commuters can expect delays of between 5 to 10 minutes across the line as trains will lower speeds to travel over areas where newly replaced tracks are settling in."