I did the two-stop shuffle on the T just before the afternoon rush, got off at Steel Plaza and took a walk up the hill to see if Bigelow Boulevard really does hate pedestrians.

It sure does.

There is no record of anyone attempting to walk the sidewalk along the boulevard from Oakland to Downtown. Americans don't go in for long urban walks much anymore. But anyone fool enough to try would discover, not long after he got past the big french fries sculpture in Frank Curto Park, that the sidewalk ends on the cliff overlooking Downtown.

Former Mayor Tom Murphy, who now teaches a class in environmental studies at Chatham College, was telling his students about this last week at an evening lecture I crashed.

Murphy guesses the sidewalk disappeared in the mid-1980s about the time these students were entering the world. PennDot was extending Crosstown Boulevard and building the Veterans Bridge then. Including a sidewalk wouldn't have cost much compared to a multimillion bridge and highway, but "people assumed nobody would ever want to walk in from Oakland.''

Walkers are, at best, pests to traffic engineers. There's a reason morning traffic reports don't bother with what sidewalks are out. Cars rule.

I own a car and can't imagine living without one, but in recent years I've begun noting places like Bigelow's Walk of No Return.

I began my mental collection about a half-dozen years ago when I noticed an intersection in Cranberry where it was illegal to walk across the street in any direction at any time. If you ever reach the corner of Route 19 and North Boundary Road without a car, you better go back and get one or you'll be stuck there forever. Red-slash-through-the-pedestrian signs are in all directions.

Though the township's leaders have been doing yeoman's work in requiring sidewalks with new development, they're bucking a cultural tide. The last time I checked, PennDot had more than one intersection of Route 19 marked with signs saying, essentially, no bipeds allowed.

I once tried to cross the intersection of Routes 8 and 910 in Richland because a townhouse developer there had said the Gibsonia post office was within walking distance. I hadn't realized that "walking distance'' was a North Hills figure of speech like "stone's throw.'' There were no sidewalks at that intersection because nobody was any more expected to walk than they were to throw stones.

So what's the problem? Well, it's probably nothing. We've sprinkled places like this across the landscape for decades, to no great ill effect apart from expanding waistlines and that oil addiction the president mentioned.

But a movement in California (where else?) is warning that our built environment is about to bring us down. A Web site called "Life After the Oil Crash'' begins:

"Dear Reader, Civilization as we know it is coming to an end soon.''

They argue that the world's oil production is about to peak, if it hasn't yet. We will be forced to adjust in a hurry as demand outstrips supply in an ever larger, more industrialized world. There aren't enough alternative fuels, hybrid cars and arctic oil patches to keep that from happening.

"The issue is not one of 'running out' so much as it is not having enough to keep our economy running,'' writes Matt Savinar, the man behind the Web site.

The U.S. Senate's recent decision to raise the national debt ceiling to $8.96 trillion, the fourth increase in the past five years, means we can continue to borrow $2 billion a day from foreigners to finance government spending. That means our current model of using Arab oil to drive to the mall to buy Chinese goods so they can buy our bonds is in no immediate danger. It's just hard to see that as a model built to last.

The "peak oil'' Cassandras are a bit reminiscent, of course, of the Y2K crowd with its doomsday scenarios. You get the sense that some of them are rooting for a crash for the sheer thrill of the spectacle.

I guess that's a long way from Murphy and his tale of discovering Bigelow's Walk of No Return the hard way. He was running on the sidewalk seven or eight years ago when it came to a sudden end, leaving him with a terrifying 100-yard run along the highway before reaching Downtown.

The end of cheap oil won't be so sudden. Signs are everywhere. We drive past them every day.