BILLERICA — For years, Lowell resident Dennis Estrella has commuted via bicycle to work in Burlington. Navigating the main routes and traffic is tricky and after testing out various routes Estrella identified the one that felt safest, but the trade-off was a few miles on the Middlesex Turnpike.

On Sept. 24 in Billerica, a car turning off of the turnpike hit Estrella.

“Next thing that I know I’m getting up from the ground or I’m on the ground,” Estrella said.

He suffered a broken nose, broken orbital bones and a concussion.

According to Estrella, the driver did not use his turn signal. A witness confirmed that the driver did not use a signal, the police report notes, but the driver told the responding officer that he had signaled.

According to Estrella, the witness said the driver turned his signal on after the crash.

The driver was not cited.

The lack of a citation bothers Estrella. He wondered what message it sent the driver.

“It just bothers me that someone can go through a stop sign and they’re very willing to give a ticket, but this person didn’t signal and hit me but they didn’t give a ticket,” he said.

According to Billerica Police Deputy Chief Roy Frost, it is up to the responding officer to determine whether to issue a citation.

Frost reviewed the officer’s report and determined that the officer handled the crash appropriately. The driver had no prior citations or traffic stops for similar traffic violations.

“I know Mr. Estrella is upset; he thinks a citation should have been issued,” Frost said. “I do believe that the officer did take the investigation seriously and did the best job at the time.”

The officer gave the driver the benefit of the doubt, Frost said.

When it comes to traffic enforcement, officers look at the driver’s history, state databases, consider mitigating factors and determine whether a citation is necessary. Sometimes they decide it isn’t.

“Just stopping and speaking to someone about why you did what you did has a significant impact as well,” Frost said.

Enforcement is a key part of cyclist advocacy, but it goes hand in hand with other elements including education and engineering, according to Massachusetts Bike Coalition (MassBike) Executive Director Galen Mook.

Police departments can’t enforce everyone, which is why education about cyclists’ rights and infrastructure engineered to promote self-policing are important, Mook said. However, changing driver behavior also includes changing how police officers respond to crashes and protect cyclists’ rights.

The way police departments approach traffic enforcement is pretty varied, Mook said, but overall it tends to be lackadaisical.

Enforcing laws around driver behavior like double parking in bike lanes and distracted driving would help, Mook said.

“There is a significant lack of appropriate punishment for drivers who cause crashes and threaten the lives of bicyclists,” said Morgan Lommele, state and local policy director at PeopleForBikes.

The September crash was not Estrella’s first. About 10 years ago he was hit by a car in Bedford and the responding officer questioned Estrella’s right to be riding on the road. It demonstrated a lack of training and concern, Estrella said. He feels similarly about how the Billerica crash was handled.

According to Mook, many officers tend to take the perspective of the driver because they spend much of their time driving.

“A lot of officers take the view of the driver in the incident and can (see) ‘oh I didn’t see that person’ as an excuse for a crash when legally that’s no excuse,” Mook said. “It manifests in a lack of charging.”

For officers who do attempt to bring charges, the system can break down if the District Attorney’s office does not prosecute, Mook said.

“I think it comes down to training. I think it comes down to the police officers trained in the full rights and responsibilities when it comes to bikes,” Mook said.

According to Frost, the department participated in a dedicated, in-service cyclist training curriculum about two years ago. The department also subscribes to legal update services for notification when laws change.

“There’s a lot of laws in the commonwealth as you can imagine and a lot of areas of concern,” Frost said.

The creation of bike lanes in Billerica is helping.

“We’ve been lucky enough that more bike lanes are being designated on major thoroughfares,” Frost said.

The section of the Middlesex Turnpike where Estrella was hit is a difficult spot for cyclists due to ongoing road construction, but that should change when the work is completed and a bike lane is added, Frost said.

The goal is to connect the bike lanes in town and the Yankee Doodle Bike Path should also help, Frost said.

According to Mook, municipalities need to rethink infrastructure and look at creating independent bike lanes and light cycles.

“Our entire roadway is built and engineered for automobiles and we’re trying to put cyclists in an automobile setting,” Mook said.

The rail-trail system being created across the state is one way to address this need, but the larger need is to create a safe network throughout municipalities.

“If you commute on a bike it’s not if you’re going to get hit, it’s when and how bad it’s going to be,” Estrella said.

There also needs to be a cultural shift. Mook said many drivers on the road see cyclists as an object and as competition. There’s a dehumanization on the roads, he said.