PALMYRA When it's seven degrees outside and Arctic clipper winds are shrieking across South Jersey, Bob Royds still prefers his bicycle to a car.

"It's not as bad as you'd think," he said Friday as he stood with his bike before the snow-heaped base of the Tacony-Palmyra Bridge. "You're much colder waiting for a bus. On a bike, you're moving."

But the slim, bearded Royds - whose shirt reads "Burn Carbs, Not Gas!" - is not moving lately in ways he wishes.

"I've been a bicycle commuter for 10 years," the 44-year-old explained. "I live in Merchantville and run a concrete plant on Castor Avenue" in the Wissinoming section of Philadelphia.

"I'm used to commuting over this bridge five, six, seven days a week."

Since Tuesday, however, snow has blocked the bridge's pedestrian paths, and bridge police are stopping anyone who tries to walk or bike across.

So Royds has been obliged to pedal south to Camden twice each day, cross the Ben Franklin Bridge, and ride north again. The route, he said, has nearly doubled his normal 10-mile ride.

"They shut it down Tuesday at 10 a.m., and it's still not open," he said Friday afternoon. "I'm sorry, but it boggles my mind that police have the right to enforce a closure on the only [24-hour] pedestrian crossway across that river."

As he approached the bridge to show the lingering snow and the gates reading "Pedestrian Pathway Closed," a Burlington County Bridge Commission police officer pulled up to tell him he was not allowed to cross.

"I have six hours to get my sidewalk cleared," Royds told the officer. "I don't understand why you people can leave this for 80 hours."

The officer shrugged. Snow shoveling, she said, was not a police issue.

As the officer drove off, Royds said his frustration with the Tacony-Palmyra was driven in part by the fact that the bridge was usually so pedestrian- and bicyclist-friendly.

"This is Mother Teresa compared to all the others," he said.

Like the Burlington-Bristol Bridge to the north, the Betsy Ross and Walt Whitman Bridges are barred to pedestrian and bicycle traffic. The paths along the Ben Franklin Bridge are clear and open by day, he said, but are closed at night.

"They do a really nice job keeping it clear," he said of the Delaware River Port Authority, which operates the Ben Franklin. "But after dark, I have to take the train across."

Patrick J. Reilly Jr., public safety director for the Burlington County Bridge Commission, defended the decision to close the pedestrian paths on the Tacony-Palmyra.

"Our first concern is the safety of the traveling public," he said, and the commission's priority is clearing vehicular road surfaces. By the time crews attended to those in the latest snowfall, he said, snow on the pedestrian paths had caked "into a half-mile of ice" on either side.

Chipping the ice with pikes and shoveling it off was not a good use of limited manpower, Reilly said, since few people traverse the bridge when weather is this raw.

Barring pedestrians and bicyclists from the paths in current conditions "was a decision to err on the side of caution," added Liz Verna, spokeswoman for the commission. "Imagine if someone slipped up there and fell into traffic."

Commission work crews had been "tireless" in maintaining roadways, she said, "in the face of what has felt like endless storms this season."

Royds said the decision not to clear pedestrian paths seemed a breach of the bridge commission's mission statement to provide "safe, accessible, and affordable bridges." But it appeared he had little choice but to wait for warm temperatures to reopen his route.

In the meantime, driving was not an option for Royds, whose commitment to "green" commuting he traces to reading Henry David Thoreau's Walden in seventh grade.

"I gave my last car to my daughter about three years ago, when she started to drive," he said. "I feel driven to maintain a car-free lifestyle. I wish more people would."