Every weekday morning, Merry Jo Kerekes takes her 3-year-old son Jacob from their home in Arlington to a day-care center in Foggy Bottom. They travel by subway, and they begin their journey at Rosslyn. The trouble begins there, too.

The Rosslyn station has an escalator that's approximately 2,546,194 miles long. That's a lot of escalator time for a mother to watch a 3-year-old. It's also a time of daily worry in light of the tragedy that occurred in January, when 3-year-old Melissa Gilbert was strangled on a Metro escalator after the strings on her parka got caught under a comb plate.

Since worrying is no fun, Merry Jo and Jacob take the elevator at Rosslyn whenever they can. But it's often broken. So there they are, in morning rush hour, as the stampede is in full swing, riding the escalator down into the depths.

How should they stand so that Jacob is safest?

Merry Jo has tried keeping him to one side of her. That succeeds only in blocking the "passing lane" and getting either mother or son gored with flying elbows and umbrellas as impatient people push past.

Merry Jo has tried keeping Jacob behind her. But it's hard to see him. She has tried keeping him in front of her. But it's hard to prevent him from running ahead -- and perhaps starting to tumble head over heels.

What does Metro recommend?

Marilyn Dicus of Metro suggests keeping a child either in front of or behind the parent, and holding his or her hand. But even more important is that parents not allow children to sit on the steps, or to run or jump as they get on and off the moving stairs.

"They think it is a ride," said Marilyn. "It isn't."