I'd love to find the guy who designed the escalators for our subway system. I want to ask him why he made sure that only 1.7895 people can stand on any one step at any one time.

This leads to all sorts of comedy, high as well as low. Take, for example, a one-act drama I caught the other day while entering the system at Van Ness-UDC.

Several young people, apparently UDC students, were riding the escalator down. They kept right, as the signs request.

A gent dressed for business tried to pass in "the left lane." But he was not .7895 of a person, so he brushed against one of the students.

The student waited until the gent had progressed out of earshot. Then he muttered, with shocking malevolence:

"Yuppie!"

Then there was the time at Metro Center when my worst fears came true.

For ages I had worried about this, warned about this, counseled public officials about this, offered to testify at congressional inquests about this. But as I predicted, once given half a chance, there was no holding back the dreaded outbreak of . . . .

Briefcase Clash!

B.C. reared its ugly head on a Metro escalator, too. As with the Van Ness incident, it began when one citizen tried to pass another.

But the guy in the right lane was carrying his briefcase in his left hand, and the guy in the left lane was carrying his briefcase in his right hand. With a sickening smash, the two cases collided.

Hasps sprang open. Paper clips flew. As women and children gasped in horror, letter openers and uneaten ham sandwiches scattered everywhere.

It took five minutes for the two antagonists to finish picking up their Texas Instruments calculators and People Express quick-reference timetables. Neither "clasher" called the other a Yuppie, but you could tell from their eyes that they were thinking it.

So boo on you, Mr. Escalator Designer.

May your Texas Instruments calculator develop bum batteries.

May strangers call you a Yuppie to your face.

May your grandchildren be forever trapped in the subway system without change for $20.

You could have given us effortlessness. Instead, you gave us 78.95 percent of it.

Speaking of airlines, they continue to be either very good or very bad, and never anything in between.

Very Good Episode: I'm checking in at Dulles for a flight. So is half the rest of the world. The line snakes off toward the far reaches of Loudoun County. And with its usual scheduling brilliance, United Airlines has five flights leaving within 15 minutes of each other, thus placing 800 people in danger of missing their planes instead of 160.

Often, in such circumstances, one of the gate agents will crack under the pressure. He'll send a Chicago bag to Honolulu. Or a Honolulu bag to Chicago. Or neither bag to either place.

But I got a guy who did something so wonderful I could hardly believe it. He checked my two bags to Denver and then said:

"Will you please watch me put them on the conveyor belt?"

"Huh?" I said, with my customary eloquence.

"Watch me do it," he said. "Sometimes when we get busy I forget to do it. This way, you can doublecheck me."

So I doublechecked him. Four hours later, I reclaimed my bags in Denver, without incident. And I tipped my cap to a gate agent who knew how to massage the system in the customer's favor.

Very Bad Episode: United Airlines check-in counter at Denver. I arrive 45 minutes before flight time. Should be plenty. But it almost isn't.

As is my lot in life, I choose the slowest line of the 15 or so that are open -- behind skiers heading home to South Bend, Ind., behind soldiers trying to stand by for a flight to San Francisco, behind some lady who thought U-N-I-T-E-D spells Delta. I finally reach the counter 10 minutes before flight time, nervous and not hiding it.

The gate agent starts to check me in.

The computer won't let her.

I say something like, "Awwwwwghrrrrh!"

She fiddles and fumbles and punches, but the computer still won't let her.

I say something like, "KEErrrrrrristmas!"

So she calls somebody, and learns that my flight has been canceled.

Worse, she learns that my flight has been canceled for the last two hours. Yet they have only just posted that information on her computer screen, and on the arrival/departure television monitors.

Luckily, Levey is still enough of a sprinter to cover the quarter-mile to the Frontier counter in less than three minutes -- just enough time to make another flight. But surely United should have had agents roaming up and down the lines of would-be checker-innners to warn them that the 3 p.m. flight to Los Angeles was canceled and to suggest that they head for Frontierland instead.