he PATH train lurched around a bend and emerged from the darkness of a cast-iron tube into the morning sun. Reaching for her husband's arm, Carol Webster, 60, turned to face the exposed guts of ground zero for the first time.

Together, Mrs. Webster and her husband, Morris, took in the slurry wall and the tangle of equipment on the floor of the pit as it inched past. All around them, other rush-hour commuters craned their necks to gape. Mr. Webster, who had tagged along with his wife to lend moral support, whispered a reassurance to her, "When you fall off a horse, you have to get right back on." She nodded but kept her hand on his arm.

Yesterday, on a morning that proved at once painful and uplifting, downtown workers streamed into the heart of the former World Trade Center site for its first rush hour since the terrorist attack on Sept. 11, 2001. For more than two years, Mrs. Webster, assistant director of admissions at Alliance Theological Seminary, has avoided ground zero, even though her office is just blocks away in Lower Manhattan. The last time she was there was when she stepped off the PATH station escalators to the concourse just as the first plane slammed into the north tower. With a stampede of others, she ran for the exits, dodging cascading debris and panicked people. The memories of what she saw outside — people burning, pieces of airplane falling from the sky — haunt her. Yesterday morning, it flooded back as she returned to the rebuilt World Trade Center station, which officially opened on Sunday.

"I didn't expect the openness of it," Mrs. Webster said. "I thought I could walk upstairs and choose to look at it or not."

The station is only temporary. The concourse level that used to bustle with stores is cavernous. It is enclosed by latticework and semiopaque sheeting, adorned with inspirational quotations, that only partly obscure the surrounding trade center bathtub. Although many commuters said yesterday's rush hour was a step toward normal life in Lower Manhattan, many also said normal was close to impossible here.

As workers charged up the escalators and out of the station yesterday, a woman in the concourse gripped a latticework wall and wept. Outside, a woman waited patiently for her husband to arrive on the next train, because they never ride the same train to work anymore.

Numbers on how many rode yesterday will not be available until today, but commuters and Port Authority officials said the figures were much lower than before Sept. 11. Officials pointed out that yesterday was the start of a holiday week and that many of those who used to come through worked at the World Trade Center. They are expecting 20,000 to 30,000 commuters a day by the end of next year, compared with the 67,000 who used to come through.

At 6:30 a.m., before the main rush began pouring through, the station was mostly deserted. A gaggle of police officers stood watch on the mezzanine level, and Maria Gutierrez, manager of the Hudson News, bustled about readying newspapers and tidying up her store. For two years, she has been working elsewhere, but this morning she was back home, around the same spot she where had worked for four years.

In stages, Port Authority workers switched on the array of escalators in the bank known as "PATH Hill." By 7:30 a.m., all eight were moving, groaning and creaking as they delivered growing numbers of commuters to the concourse, where they were greeted by the beeping of construction vehicles at the site.

As the Websters wandered through the concourse a half-hour later, Sean Coughlin, 40, got ready to board his train in Hoboken with a mixture of dread and anticipation.

Mr. Coughlin, a lawyer for Citigroup Global Markets, managed to flee to New Jersey on Sept. 11 aboard the last PATH train to leave the city that morning. After the attack, Mr. Coughlin, who lives in Montclair, N.J., joined the thousands who lined up for ferry service in Hoboken. He later switched to a New Jersey Transit Midtown Direct train, which meant a subway ride downtown. Both options were significantly slower than his old PATH route.

After disembarking yesterday morning, he walked slowly up the stairs, absorbing everything.

"It's all the same layout," he said. "Wow. The same, same thing."

Coming up to PATH Hill, he swiveled his head to look around, clearly stunned. At the top, like many others, Mr. Coughlin was taken aback by how exposed everything appeared. "I worked right over there," he said, pointing off to his left, where 7 World Trade Center once stood.

Also arriving from Hoboken were Anthony Gardner, Bruce DeCell and Patricia Reilly, all wearing yellow ribbons in memory of relatives killed on Sept. 11. Although only Mr. Gardner is from New Jersey, the three, members of the Coalition of 9/11 Families, rode in together yesterday to experience it. Afterward, they wandered to the side of the concourse and gazed down in silence.

By 9:15 a.m., the surge of commuters had begun to taper off, and Lori Manning and her husband, Harlan Greenberg, rode up the escalators, with Ms. Manning dabbing away tears. On Sept. 11, the couple was among several hundred commuters on the PATH train into the World Trade Center that was diverted to Christopher Street by some quick-thinking Port Authority workers. In the last two years, their hourlong commute stretched to two hours.

Even though they had been watching the construction at ground zero unfold from their offices and were eager for the station to reopen, they were not prepared for the close-up encounter with the site. As their train had rolled around the bend, Ms. Manning, along with a woman across from her, broke down. "It's different being in it," Ms. Manning said.