As with most things, there is much more to the production of TV shows than meets the eye.

It seems trite to compare them with icebergs, with nine-tenths of the bulk hidden, but that is about the size of it.

Consider "Route 66" as an example. Since show biz in the form of filmed network TV series had never before ventured to Cleveland, it seemed worthwhile to put in a couple of days with this roving production unit.

Charley Connors, an off-duty Cleveland policeman helping with the program, put his finger on a problem that I never knew existed.

"We had to tow the stars in their Corvette across the High Level Bridge four times before we got it right," he said. "every time some other kind of car got in the scene and we had to do it over."

The program producers make almost a fetish of showing no autos but Chevrolets in the films. When the policemen, unaware, showed up in Plymouth cruisers, they were sent away, heads hanging, to round up some Chevies. Chevrolet, one of the program's sponsors, is sensitive on this subject.

The crew's propmen are remarkably adept at salvaging situations of this sort. Using tape, they quickly blocked out the word "Police" on a couple of stock Chevies. They even created 1961 Ohio license plates to cover up some Illinois plates that would have mixed up the audience, which is supposed to contain a number of sharp-eyed license plate spotters.

One of the scenes, filmed near the railroad lift bridge at W. 11th Street and Front Street N.W., will amount to about 10 seconds when you see it on your screen at home, probably at 8:30 p.m., Friday, June 16. On location, it took a couple of hours to film.

On hand were supposed to have been a diver and a railroad handcar. Neither showed up on time. The bridge kept going up, to let ships through on the river, and down, to allow freight trains to pass.

At one critical point, a riverbank scene had been filmed. The next scene was a closeup, in the same location. Just then a freight train came along, the bridge was lowered for it, and a Danish merchant ship appeared heading toward the river mouth.

Its captain had to drop anchor to slow it until the bridge could be raised again. Hence it would have appeared in the closeup, but not in the long shot. Production was stopped until it could hoist anchor and sail on, perhaps all the way to Copenhagen.

Only once did the passing freights come in handy for the filming. This was when series heroes, George Maharis and Martin Milner, were supposed to be isolated from the railroad bridge by a passing train. It was not hard to arrange. The camera crew filmed the scenes through the train.

An interesting delay came about when the director sent a stunt man and a double girl climbing to the top of the railroad bridge in an escape scene. They were supposed to represent Nehemiah Persoff and Lois Smith, who have the leads outside the regular stars.

But once up on the bridge, the double girl (apparently twice as good as a single girl) became frightened and another helper had to be sent aloft to aid in the descent.

At one point, after almost two days of filming, I asked one of the crew members how it was going.

"Well, we've got about 3-1/2 minutes of film in the can," he said, with something less than enthusiasm for the waterfront location. Things, he hinted, move a little faster in the Hills of Hollywood.