As dawn broke crisp and clear Tuesday over a hushed Boston, trains rolled steadily through the city, largely without incident or delay.
Commuters spoke in whispered tones, stared into phones, or peered over the shoulders of their neighbors to eye the horrific images from the Boston Marathon on the pages of newspapers.
“Obviously, you don’t really want to take public transportation right now,” said 23-year-old Shelby Zawaduk, who said she feared trains could be a target. Waiting at Park Street Station for a Green Line train, she eyed men in military uniforms stationed on the platform. “But seeing the guards definitely makes me feel better.”
For many of the day’s commuters, the sight of Boston police officers, state troopers, SWAT teams, National Guard members, and police dogs at MBTA stations brought a small measure of relief to a region trying mightily to go about the business of regular life.
Every subway car, trolley, and bus was checked before the start of service Tuesday morning, said Joe Pesaturo, spokesman for the Massachusetts Bay Transportation Authority. Train operators on the Green Line informed commuters that Copley Station would be closed all day.
At stations around the city, law enforcement officers paced up and down train platforms, rifles in hand. At Arlington Station, National Guardsmen asked commuters heading into the station to open their duffels and purses for a security check. “No guns, no bombs?” asked one, pulling back the zipper of a backpack.
Pesaturo said federal, state, and local law enforcement personnel were conducting random baggage checks throughout the subway system.
“Customers have been very cooperative, and we greatly appreciate their patience and understanding,” he said.
Lighter-than-normal traffic on the T mirrored the relatively clear highways, which officials attributed to it being school vacation week.
In the hours after the bombings, Hubway bicycles all but vanished from the stations surrounding Copley Square and Boston Common as runners and spectators fled the scene. Taxis were difficult to flag and stretches of the T closed down, so some found the bikes the quickest way to weave through the throngs of ambulances and barricades and gridlocked traffic, and put distance between themselves and the explosion site as fast as they could.
Bryan Hogan, a Malden resident, left work in the Financial District Monday evening but grew anxious at the thought of taking the T home. Cabs seemed impossible to flag. So he called Hubway. An employee said they would not charge him to keep the bike overnight, since there were no stations in his hometown.
“I think I stopped at one red light the whole way home,” Hogan said.
On Tuesday, many returned to their regular commute, but eyed their surroundings with wariness.
A years-old automated message on the T — “Now, more than ever, it’s important to be alert” — took on new significance after the blasts that killed three people and injured scores more. After the bombings, MBTA officials decided to play the recording on a frequent loop.
Mike Gruet, 23, of Acton, said guardsmen searched every bag at the Alewife T stop on the Red Line in Cambridge, where he boarded.
“It was nice to see,” said Gruet as he waited for a train at Downtown Crossing.
At the Massachusetts Avenue Station on the Orange Line, a state trooper stood at the entrance while another monitored the platform, pausing to look in a trash can.
At Harvard Square Station, guardsmen stood at every turnstile.
Early in the morning, a B line train heading inbound dipped underground and rolled toward Kenmore Station. “Due to yesterday’s tragic events,” the driver announced, “there is no service at Copley. The whole area is a crime scene.”
“Don’t leave anything behind,” he added. “Your belongings, your bookbags. If you see someone leaving something, remind them to take it with them.”
Minutes later, at Copley Station, the train rolled slowly past deserted, unlit platforms.
Increased police presence on the MBTA system eased the minds of some out-of-towners.
“I feel very comforted that they’re here,” said Dan Murray, of Spokane, Wash., who ran the Marathon on Monday.
The train ride, he said, reminded him of the days after Sept. 11, 2001 — police everywhere, everyone on their guard for anything unusual.
But to some, the scene on trains and in stations amplified concerns about safety.
Elizabeth Corkum and her husband, visitors from Canada in town for the Marathon, said they were unnerved to see the magnitude of the police presence.
“It makes me more nervous. We’re from Nova Scotia — we’re not used to any of this stuff,” said Corkum, 46. A seven-time Boston Marathon runner, she had finished the race just a few minutes before the explosions went off.
Seated near the back of a Green line train headed outbound, she and her husband, Andrew, said they planned to walk around and take in the city, so much quieter and more listless than they’d ever seen it before.
“We’re trying to enjoy the city,” Corkum said. “But the mood — it’s so hard to be happy.”
Robert “R.W.” Abel, 29, said he visited Boston over the past few days and rode the T on Tuesday morning on his way to Logan Airport to catch a flight back to his home in Texas.
“I’m not nervous,” he said. “I think some people are really uncomfortable. But it is what it is. You’re never really safe where you are at any given time.”
In the afternoon, Gus White, 34, sat in Arlington Station, a solemn expression on his face.
“I walked from Brookline to here,” White said. “As soon as you get to the Fenway — you can just tell. Everything feels different.”Globe correspondents Matt Rocheleau and Johanna Kaiser contributed to this report. Martine Powers can be reached at email@example.com. Follow her on Twitter @martinepowers.