His hobby, or rather his obsession, is climbing bridges.

For years he did it under cover of darkness, the thrill of achieving such heights underscored by the even more exquisite thrill of getting away with it.

Today, getting caught is the least of his worries. Peter Rose, 32, an independent filmmaker and assistant professor at Philadelphia College of Art has a $10,000 grant from the National Endowment for the Arts to film his own ascent of the formidable Golden Gate Bridge in San Francisco.

He also has the permission of bridge authorities -- something not easily come by.

"Initially they said no," explained Rose, an agile, bearded man whose training as a dancer stands him in good stead when he is climbing steel cables. t

"They said no for a long time. At first they wanted me to take out $1 million in liability insurance [later reduced to $500,000]. They brought it up before their board of directors, who voted it down."

Rose was not the first to be turned down by San Francisco bridge authorities -- Italian filmmaker Lina Wertmuller and many Hollywood directors have been rebuffed over the years.

To overcome such entrenched resistance, Rose turned to the celebrated Romanian artist Christo, whose wrapped buildings and other large scale projects have required extensive cooperation from public officials.

"He shepherded the whole project," Rose said. "He cornered the commissioners, and advised me to make a presentation at the Nov. 30 board of directors' meeting."

The strategy worked, and for the first time a layman will climb the bridge legally. Rose plans to do so in March, when the weather should be favorable. Bridge authorites have stipulated that Rose must wear a safety harness and hire an ironworker -- at union scale -- to go up with him.

How did he come by such a spinetingling mania?

"I grew up near two bridges -- the Throgs Neck Bridge and the Whitestone Bridge," Rose said. The two bridges, on the north shore of Long Island, "were fairly potent landmarks. Bridges were where we used to go as adolescents. They were free zones. We used to go there at 2, 3 in the morning.

"A bunch of us, when I was 15, climbed up the hinges of a little powerhouse underneath this bridge. Then we crawled along these pipes. We crawled and crawled for about an hour. Suddenly we came upon a catwalk under the highway -- about 150 feet high.

"We got inside that thing and went all the way over" to the other side. "We decided since we got that far, we really ought to think about going up the cables," Rose said.

"The next thing you know, you're up there about 600 feet! When you get up to the top, these towers are honey-combed with tiny little rooms, thousands of them, with ladders between some of them. You can get lost in there."

Rose described climbing a bridge as "a very humbling experience.

"I don't do it by any means lightly," he said. "I approach it with caution. When you go up, the scale of your movements relative to the scale of the bridge is minuscule. You're moving, but nothing is changing. You get kind of lost in space. Because of it, something hits you in your gut."

Scaling a bridge is an act of mythical proportions and, Rose said, "it's a very ritualistic thing.

"I'll spend a couple of weeks thinking about it, and most bridges I spend a lot of time looking at."

Only after deliberately sizing them up does Rose climb them. He explained: "I like to set challenges for myself. It gives me a feeling of conquest, of power. The physical challenge definitely meets some kind of physical need.

"Certain kinds of things are not well looked-upon these days. To encounter something large and inspiring, and do it in such a blatant way -- it's an act of ambition and conquest that I, among others, have been trained to sit on a little bit.

"Our lives are constrained by all kinds of things," he continued. "The idea that you can do something that is large and unbounded exposes you to a lot of anxiety."