Bevan M. French of Chevy Chase was puzzled by his ride on an L-7 express bus a few days ago and asked me to help him get some answers.

French's bus had left Chevy Chase Circle at 7:20 a.m. and "crawled down Connecticut Avenue at a top speed of 10 to 15 miles an hour," although traffic conditions would have permitted a much faster pace.

When an impatient passenger asked whether the driver couldn't go any faster, she "announced in a loud, firm voice that she was exactly on schedule, that she was due at Connecticut and K at 7:48, that she was not going to arrive there any earlier than that, and that if anybody was going to be late for work as a result, he should have taken an earlier bus."

What made matters worse, said Bevan, was that en route to K Street his "express" bus was passed by many others, including locals. Naturally, he wanted to know how Metro explains such service.

I was pretty sure I knew the answer to Bevan's question, but to get an official reply I took the question to Cody Pfanstiehl, who can explain even the inexplicable.

In mass transit jargon, a bus or train that runs ahead of schedule is "running hot" -- and running hot is one of the greatest sins an operator can commit. A passenger who knows that a bus is supposed to arrive at his corner at 7:31 is likely to be infuriated if he gets to the bus stop 15 seconds before 7:31 only to see the bus pull away without him. It does no good to tell that passenger there is supposed to be another bus along in 10 minutes. He's mad as hell and isn't interested in listening to explanations.

So Cody says the bus driver did nothing wrong. She was merely following her strict orders not to "run hot."

Although it is not pertinent to the point at issue here, there is an interesting sidelight to this story.

Bevan's bus arrived at Connecticut and K at 7:52, not 7:48. After all that crawling, it was late.

The bus had remained on schedule at outlying pickup points, but then had fallen four minutes behind schedule when it hit heavy traffic downtown.

A transit company understands traffic delays; they afflict all of us and cannot be avoided. A transit company does not understand running hot and thereby denying service to people who were at their pickup points on time. Running hot can be avoided. POSTSCRIPT

Incidentally, Cody Pfanstiehl made some interesting comments about Metro's bus routes in general. He said:

"When Congress told the public to take over the four ailing bus systems in this area in 1973, we inherited a network of routes that looked like a can of spaghetti thrown against a wall. As the routes are coordinated with the growing rail system, we are trying to simplify things. In 1973, Bevan French and you and I inherited 750 bus routes with 1,500 variations. Today we are down to 371 routes and 888 variations."

Another thing Cody wishes we'd keep in mind: "Metro does not tell the District or Arlington or Montgomery or any local government how many buses it will have, where they will run or how often. Each of our eight local jurisdictions subsidizes its own bus service. They tell us how much, where and when."

See what I mean about Cody being a good explainer? ADDENDUM

Having begun today's column with Metro, we might as well take note of a few other public utility items.

In June, Washington Gas will begin sending you completely redesigned and more detailed bills. The postcard bill that has been in use since 1956 is being scrapped. Your new gas bill will measure 7 inches by 8 1/2 inches and will require an envelope.

If you live in a distant suburb and didn't get one of the new "D.C." telephone books, here's why: Last year, 1,952,000 copies of the Washington white pages were distributed. If the same distribution policy had been followed this year, more than 2 million copies would have been needed.

To save money, C&P conducted a survey that indicated what surveys are supposed to indicate, namely that it's a good idea to do whatever it was you wanted to do in the first place. The C&P survey indicated that "residents in farther removed suburban areas don't make that much use of the D.C. white pages," so distribution will henceforth be limited to neighborhoods near the District of Columbia. About 573,000 copies will go to District subscribers, 316,000 to nearby Maryland neighborhoods, and 243,000 to nearby Virginia. The amount that will be saved has not been made public, but you can bet it will be substantial.

I'm not complaining, mind you. Any dollar C&P can save is a dollar it does not have to ask us to repay in rate increases.