My mail correspondents tell me that some Metro passengers are getting stuck in the train car doors, or trapped in cars, or are unable to enter from the outside because doors have closed.

Here are some of your specific complaints, along with responses from Lisa Farbstein, spokeswoman for Metro.

Dear Dr. Gridlock:

I have had doors close on me twice in Chinatown. Once I was caught halfway into the doors, and later I was just stepping in. I had to struggle to free myself. There has to be a better way for Metro to monitor when to close the doors.

Marcie Lovett

Olney

Ms. Farbstein: "When the chimes start, the doors will close 3.8 seconds later. The operator has a schedule to keep . . . and will press the 'Close' button when it is time to go.

"If someone gets stuck, or an item like a backpack gets stuck, the operator can open the doors enough to free the object. The train will not move with a door ajar."

Dear Dr. Gridlock:

Some train operators seem to be in too much of a rush to close the doors. I've seen the "door closing" announcement while people were still exiting the car. I would hope the operators could provide sufficient time for the passengers at least to exit.

Michael Richmon

Bethesda

Ms. Farbstein: "We encourage people on the platforms to make way for the people getting off. And for people bunched at the doors to step aside and let passengers off."

Dear Dr. Gridlock:

I've often watched those doors slam shut the very second of the chimed warning, and wondered how in the world anyone is supposed to have time to react to the warning before getting caught in the doors.

I've had suitcases on roller wheels, a briefcase and umbrellas caught because the doors close simultaneously with the chimes.

Linda Meyers

Arlington

Ms. Farbstein: "When you hear the chime, step back. The chimes work like a yellow traffic light. Caution. The doors won't snap back, like in an elevator."

Dear Dr. Gridlock:

This morning was a new one for me. A Blue Line train to Largo pulled into Farragut West, and the operator forgot to open the doors! Then the train moved on to McPherson Square, with no explanation or apology.

I'd be interested in knowing Metro's explanation.

Jessie Sackett

Arlington

Ms. Farbstein: "That suggests a problem with the doors. Passengers should press the intercom and inform the driver."

Dr. Gridlock here. With Metro straining to accommodate record loads -- more than 600,000 trips daily -- getting on and off is only going to get more difficult.

Some suggestions: Reconfigure the cars to discourage bunching up at the doors (being done on new cars); adjust the braking so each train can stop at a precise spot (being looked at); enter at the center and exit at the ends (being looked at).

I suspect you will have follow-up questions. Fire away.

Saving Time in a Rescue

Dear Dr. Gridlock:

I am 68 with a few chronic ailments. I wear a MedicAlert bracelet. However, I thought it would save time for emergency personnel, should I get involved in an accident, to make a copy of my medical records, including the medications I take, and put the information in an envelope and paste it on the dashboard of my car.

This could be a lifesaver, since the emergency personnel would not have to call the MedicAlert number and would save precious minutes.

Jim Koricki

Rockville

This seems like a good idea. Note your blood type, medications and ailments in large type on the cover page, and hope it's never used.

Transportation researcher Diane Mattingly contributed to this column.

You can write to Dr. Gridlock at 1150 15th St. NW, Washington, D.C. 20071. He prefers e-mails at drgridlock@washpost.com or faxes at 703-352-3908. Include your full name, town, county and day and evening telephone numbers. Dr. Gridlock cannot take phone calls.