Hubway, Greater Boston’s bike sharing program, said as much Monday in a Facebook post, after a cyclist was recorded on video during the weekend pedaling cheerfully on Interstate 93, on the northbound side of the Thomas P. O’Neill Jr. tunnel.

One would think people wouldn’t need to be reminded, but Hubway and state officials want to make something perfectly clear: Riding a bicycle on busy highways is a bad idea. So stop doing it.

“It is EXTREMELY dangerous and definitely illegal to ride a bike on 93 (or any area highway),” Hubway officials wrote on Facebook. “DO NOT DO IT.”

According to Massachusetts Department of Transportation officials, the incident Sunday afternoon was the fourth time this year that a cyclist made his or her way onto the northbound lanes of I-93 and entered the tunnel, a tactic officials staunchly denounced.


The state agency “strongly discourages individuals from traveling along highways using bicycles or any other prohibited form of transportation,” said MassDOT Highway Administrator Thomas J. Tinlin in a statement. “This is a serious safety issue for motorists and for cyclists.”

Brad Anderson took the video that led to the loud-and-clear reminder from both the bike sharing company and transportation officials.

The short clip, which Anderson shared on both Snapchat and Facebook, showed the man on a Hubway bike pumping his legs speedily, as he soars through the tunnel in the breakdown lane, cars whizzing by on his right.

“Todd, the kid who was driving, looked over and said, “I think that’s a dude on a bicycle,’” said Anderson in a telephone interview. “I asked him to slow down, and pulled my phone out and started recording.”

The sight was too strange not to capture on video.

Anderson said the man didn’t seem distressed or lost. In fact, when the cyclist realized that Anderson was filming his ride, he gave the group of friends, who were returning from a car show on Boston Common, a peace sign.


“He seemed calm and collected, like it was his normal routine,” Anderson said, noting that the man was well-dressed, as if headed to work.

“We were laughing at the time, because it’s so shocking to see something like that,” he said.

In hindsight, Anderson admitted, the group wished they had contacted police.

“It’s super-dangerous to do that, because people whip through that tunnel,” he added.

The speed limit inside the O’Neill Tunnel is 45 miles per hour, but many people don’t observe it.

State Police spokesman David Procopio said the number of times something like this has happened “is very small.”

“It is not a frequent problem. It’s obviously a dangerous practice,” he said in an e-mail.

Procopio said riding a bicycle on a state highway is prohibited, and carries a $20 fine. Riding a bicycle on the Massachusetts Turnpike, which has its own regulations, carries a $100 fine.

The O’Neill Tunnel incident Sunday was the second one that day of someone biking on a highway.

Procopio said around 1:19 a.m. Sunday, police received a report that a bicyclist was traveling on Interstate 90 West in Boston.

Officers located a 23-year-old man from Illinois, and transported him off the roadway, near the Boston University Bridge. The man was not charged, according to police. It was unclear if that person was on a Hubway.


Officials from the bike-share company issued a similar warning on Sept. 16, after a tweet showed photographs of a cyclist riding a Hubway on Interstate 95 South.

On Aug. 5, 2015, a person on a bike was also seen merging from Storrow Drive onto I-93 North, according to a published report. That person did not appear to be on a Hubway.

Two days later, however, a video posted by an NECN reporter showed a man on a Hubway, holding his smartphone while biking on the Turnpike.

There could be a myriad of reasons people end up on the highways.

Benjy Kantor, a spokesman for Hubway, said it’s possible — but he can’t be certain — that riders are using GPS technology on their smartphones, and being directed onto the highway by accident. It’s also possible that the riders who have been seen pedaling on highways are unfamiliar with state roadways and regulations, because they’re from out of town.

“I think it could be a number of possibilities. But I wouldn’t say any have been substantially corroborated,” he said.

Bike advocates said they don’t support this type of behavior, and fear that it widens the rift between drivers and cyclists.

“When there is bad behavior by a cyclist, it gets thrown in the face of the entire community,” said Becca Wolfson, executive director of the Boston Cyclists Union. “And it becomes reason to not give us the space that we want, and need, and deserve.”


Wolfson said she thinks drivers are quick to point out one person’s poor choices, and then associate them with an entire group.

“If every time we saw a car go through a red light, and said all cars should be off the road, and shouldn’t be there, we would have car-free streets,” she said.

While Hubway prohibits this type of activity, it also asked that drivers be cautious of the cyclists breaking the law.

“If you happen to drive past someone doing this, please be very careful and allow extra space, and do not yell at them or swerve suddenly around them,” the company said in a statement. “Even though (and because) they should not be riding there, they are extremely vulnerable. If you are able to do so in a calm, and safe, way, ask politely and sincerely if they need help. Also, call the police.”

Steve Annear can be reached at steve.annear@globe.com. Follow him on Twitter @steveannear.