The interior of the Orange Line mockup car at the T's Wellington yard in Medford.

MBTA OFFICIALS on Tuesday unveiled a three-quarters mockup of the 152 new Orange Line cars that are on order and due to start arriving at the end of this year. The wheel-less mockup allows operators, mechanics, riders, and other stakeholders to explore the vehicle and report any problems that need to be corrected. Here are five takeaways from the tour:

DOORS –The doors, at 64 inches wide, are 16 inches wider than the existing train doors on the Orange Line, so passengers will be able to get on and off much faster.  The doors are also better for wheelchair-bound riders because they come equipped with extensions that pop out from underneath the train that fill the gap between the rail car and the platform.

INTERIOR – The cars are the same width as the existing cars, but they seem roomier. Seats are made of slick plastic, which is utilitarian. Some seats flip up out of the way so someone with a stroller could fit in more easily. The cars also come equipped with screens that inform riders the destination of the train and the next station on the route. “It’s pretty clear this vehicle isn’t 45 years old,” said Gov. Charlie Baker, referring to the existing Orange Line cars, after taking a tour of the mockup at the Wellington MBTA facility in Medford.

FASTER SERVICE – The Orange Line cars are expected to hold more passengers comfortably than the existing cars, but more importantly their braking and propulsion systems will allow the new cars to stop and start more quickly. That ability will allow the trains to come into stations at 4.5-minute intervals, which will boost overall capacity on the Orange Line by 40 percent and reduce the number of crowded trains.

PASSENGER COUNTERS – The T has a big problem tracking how many people use its system. The new Orange Line cars come equipped with two infrared beams in the door systems that track by heat signature who is getting on and off. One official said even babies and pets will be counted with the new system.

BIG BROTHER IS WATCHING – Surveillance cameras in each car will allow T officials in the central command center to monitor passengers inside vehicles in real time.

Bruce Mohl oversees the production of content and edits reports, along with carrying out his own reporting with a particular focus on transportation, energy, and climate issues. He previously worked...