New Orange Line train cars expected to hit the tracks on Wednesday

New Orange Line cars sit on the production floor of a Springfield factory in late 2018.Lane Turner/Globe Staff/Globe Staff

Riders on the Massachusetts Bay Transportation Authority’s Orange Line can soon expect to see something different rumbling down the tracks during their commute. New and improved — and long-awaited — subway cars are arriving this week.

Steve Poftak, the MBTA’s general manager, announced during the T’s Fiscal and Management Control Board meeting Monday that the first of the new Orange Line trains are slated to enter passenger service by midday Wednesday, with more to follow “in succession.”

According to a report that Poftak delivered to the board, a set of six train cars will be introduced to the system. The next new set, he said, is to launch at some point in September.

The train cars have been in testing for more than a year, to “ensure the functionality and reliability of all systems,” according to the report.

“The 6 new cars entering service this Wednesday have accumulated 3,800 miles” and passed 75 different tests, the report states.

When passengers eventually step onto the trains, they can expect to be greeted by some fancy features. The sleek, shiny stainless steel trains will include much wider doors, LED lighting, LCD displays, automatic passenger counters, closed circuit security cameras, and accessibility improvements, MBTA officials said.

Passengers got a preview of what the train cars will look like last spring, when the MBTA placed a mock-up of the vehicles on City Hall Plaza.

The rollout of the new trains has been hampered by repeated delays. They were first promised to riders by late 2018. The deadline was later bumped to winter 2019, and again to “early spring,” the Globe previously reported. In March, T officials said passengers could expect the trains to welcome them aboard this summer.

The introduction of the new train cars is part of the MBTA’s larger plan to replace the existing Orange Line fleet with 152 new cars in the coming years.