Cold blooded wonderers

I take public transit to work everyday as regular readers know. The mornings are of particular interest to me, since that is the time that has seasonal or climatic variations on the experience. There is a tower clearly visible from the platform with a temperature monitor. It helps me decide how to feel: cold, cool, pleasant or hot.

This particular temperature monitor tower alternates with the digital time display. So, after I've decided that I am shivering, I can count my minutes by looking at the clock to see when I can get into the stationary train with the doors closed resolutely. I find it particularly trying in Winter, because I am holed up in a jacket, glancing at 29 F, and wondering how long it would take for my toes to fall off with frost bite. * I know it doesn't snow where I stay, but you get the drift?*

You are wondering why the train doors are resolutely shut? I formally welcome you to join the esteemed club of cold-blooded wonderers. Here is the series of events that happens in the section of time before the train departs.
* Train comes everyday 5-8 minutes ahead of scheduled departure time. (that is good)

* Train lets people who rode in out of the compartment (still good)

* Said train is a smaller one and must be linked with another half of train that arrives just before departure time. (No unrelated ideas please, it is freezing remember?)
This is where things start to get puzzling:
* The train operator announces loudly, making several jarring noises that the train is out of service, and nobody should board the train. Puzzled first-timers walk in, look around quizzically, fear a lifetime of claustrophobic experiences of being stuck in a train compartment without food or water and come out looking worried.
* Doors close.
* Then, the train operator exits, using the smallest possible timeframe to complete the act. His expression resembles most unsettlingly that of a scuttling rabbit. Any sooner and the operator's hands would jam while they are locking the doors and letting himself out. The fear of people trying to squeeze into the train for an extra minute's warmth is clearly writ large on the operator's face. There isn't a word for this phobia yet - I checked.
* A thousand glares are directed at the operator who let himself out, which he carefully ignores for his own sake.
* Second half of the train arrives devoid of passengers, is linked to the first half and the doors are still closed.
By now people's faces are slowly moving to unmistakable scowling territory.
Finally, the helpful tower flashes the time ( a minute before departure), - some people look like they can kiss the tower at this point, if only they could move their lips.
* The doors open.
* People tumble in - partially to find seats, but mostly because they've lost the senses in their legs from the cold, and are yearning for the warmth inside the train.

I've tried plausible explanations and came up with the following:

1) If somebody complains of knee pain because of the 0.00002 level jerk on the richter scale when the train is attached with more compartments, it is a potential lawsuit.
2) Fresh air is good for the soul, and the longer people enjoy the fresh air, the better it is for their health.
That is why I weighed all the pros and cons and try my best to arrive exactly when the doors open. But it is a fine line between doors opening and the train doors closing-leaving for good.