Ever feel like you're the last person left on Earth?

The blank stone facade, punched by a huge, dark opening, greeted us at the bottom of a gentle slope. We screeched our bikes to a halt to listen: silence. A clammy breeze blew out of the darkness into the humid summer afternoon, fogging the tunnel entrance. An empty hawk's nest teetered on rusted beams overhead.

The post-apocalyptic vibe of the road was slightly chilling, despite the 90-degree heat. It felt like the set of a cheesy horror flick, eerie and ominous. Then I turned around and watched my husband suddenly vanish into a mile-long, pitch-black tunnel.

Within earshot of the Pennsylvania Turnpike, we were pedaling an empty eight-mile stretch of asphalt rolling through -- and under -- the Allegheny Mountains. Thanks to a local conservancy, bikers can cruise the Pike to Bike Trail, which used to be the turnpike -- the first limited-access superhighway in the country, no less. No EZ Pass is required (though, as we later found, the risk of a summons still exists). And off-highway, Bedford County offers miles of other pleasantly deserted routes to explore over a summer weekend of biking.

The Pike to Bike became an appendix to the state's main east-west artery in 1968, when the turnpike (I-76) was rerouted through bigger four-lane tunnels. Between the old ones, Sideling Hill and Rays Hill, the discarded stretch of road was relegated to highway researchers and underage boozers. But since the Southern Alleghenies Conservancy took it over in 2001, recreational cyclists -- a few hundred each weekend -- have reclaimed the roadway (also known as the P2B or Superhighway Trail).

This freeway-to-yourself fantasy began, unpromisingly, in the Bedford area near the Maryland border.

The county has plenty of red-brick, 18th-century charm, with one exception: the mile of Route 30 in Breezewood, whose slogan "The Town of Motels" is depressingly accurate. It's 100 acres of highway cloverleaf, garnished with neon and devoid of pedestrians. The new trail modestly boosts local family attractions beyond indoor pools and free HBO to become a stop worth making in a place where most people make only pit stops.

In a town obsessed with signage, the P2B is as yet completely unmarked. We had been told to park in a gravel lot next to the Ramada Inn Breezewood and to "follow the path down the hill," where a yellow gate limply hung open. With that vague welcome, we headed east. Twenty yards later, we plunged into a secluded green valley, and the growls of downshifting big rigs faded away.

Like most trails that follow old railroad rights of way (as the turnpike originally did), the P2B is generally level. We arrived at the Rays Hill Tunnel, two miles east of Breezewood, in minutes. The three-quarter-mile passage showed a squint of light at the far end -- not enough to pedal by, but enough to be reassuring.

Inside, the 55-degree damp and a few drips from the ceiling felt blissful. When we reemerged, blinking, into Buchanan State Forest, the heat enveloped us again; we looked forward to the Sideling Hill Tunnel four miles ahead. But when it finally loomed in front of us, the prospect seemed a bit more ominous -- like an amusement-park dark ride, testing our nerve.

At 1.3 miles long, the Sideling Hill passage features a slight rise in the middle, one that you feel in the legs rather than see. I tried to steady myself by sighting my headlamp along the double white line. My husband called from 20 feet back, "I can't even see you!"

I began to ponder what kinds of wildlife were attracted by tunnels. Then we heard a yell.

"Hellooooo!" echoed a youthful voice. A swarm of flashlights danced toward us. Even as we passed the teenagers holding them, we barely glimpsed their faces. For another 10 minutes, we pedaled in damp, Stygian gloom, laughing. Nervously.

"Whether the tunnels should be lighted is a really fierce debate," trail project manager Branden Diehl told me later. The plan for trail improvement calls for dim tunnel lights and repaving, including a lane for in-line skating and a small skate park at one trail head.

For now, the trail is too bumpy for bladers and skateboarders. But on some weekends, it's taken over by real-life road warriors: Convoys of the Army's 99th Regional Readiness Command use it for Iraq training maneuvers.

Trail improvements can take years, and in the case of the P2B, that may be a good thing. The opportunity to brave the dark tunnels, before lights are installed, was a thrill that set the trail apart.

Jersey barriers blocked the eastern end of the trail at Hustontown. But seeing a tempting expanse of trail beyond, we lifted our bikes over and pedaled on. Two state police cars idled as their drivers chatted; they gave us a friendly wave. A mile later, we could see turnpike traffic dead ahead -- and another state trooper glaring at us.

"Do you know you're trespassing?" he began. Er, yes, officer. He warned us that by venturing past the barriers onto official turnpike property we were liable for a summons, which he seemed ready to issue. So we turned back, Ramada-bound.

Riding country roads, by contrast, was completely legal. And rewarding. Though Bedford County is banked with steep ridges, its valleys compensate, with plenty of quiet, well-paved lanes.

We had chosen our 17-mile covered-bridge tour from a dozen on the local visitors bureau Web site. Armed with a downloaded map and chatty point-to-point directions ("This is a great place for a picnic!"), we started off from the Fishertown Country Store.

After a mile of gaspingly hard climbing, we got our reward: a panoramic view of a valley carpeted in lush cornfields. The rest of the run, along Dunnings Creek and Bob's Creek, was easy and flat. When the skies finally opened in earnest, we waited out the storm on the front porch of the Osterburg Country Store, lounging on two dining room chairs and reading back issues of the Bedford Gazette.

About 10 miles west of Bedford, we took an evening swim at Shawnee Lake in a pleasant state park. And for the next day's box lunch, we sought out a local legend. The Road Kill Cafe may have one of the greatest restaurant names, but by the time we arrived in Artemas, a rolling 25-mile drive south of Bedford, it seemed as far as another planet. It may be the only retail establishment in three townships, which is why it sells sandwiches, hardware, gasoline, hunting gear and, of course, a full selection of Road Kill T-shirts (some bearing the slogan "You Kill It, We Grill It").

Armed with a few tasteful garments and a few turkey subs, we headed north. The road wound around Gabriel's Knob, a gloriously wooded mountaintop, and we thought how the humidity would fade into a glorious warm October. It would be a good time, we agreed, to have this corner of Earth to ourselves.

Near Breezewood, Pa., the Pike to Bike trail comprises eight miles of abandoned highway. At right, cyclists pedal toward the Rays Hill Tunnel.