“There he is. My man! He never takes his eyes off the road.”

My brother was pointing out a Triborough Bridge and Tunnel Authority police officer standing at the mouth of the Brooklyn-Battery Tunnel: Red hair, matching beard. Concentrated expression. Carefully watching every car — his stare intense. No one was getting by him.

It was October 2001, and the fear in the city was palpable. New Yorkers didn’t really talk much about how scared we were; how could we live fearful lives when the bravest among us had rushed into burning buildings and never came out? It would dishonor our dead to admit fear.

Allow our lives to be changed and the terrorists would win. Everyone knew that.

But we were afraid. Of crowds and loud noises. Tall buildings. Each other.

The people who hurt us had lived among us. They were our neighbors and friends. They used our trust against us. And they made our most powerful landmarks dust.

Suddenly our city looked like a series of potential targets, our country at risk. They got the Pentagon. How was that even possible? We were sitting ducks.

We were taking the tunnel that day because my brother was driving me back to Manhattan from Brooklyn. No way was I taking the subway. Everything was a potential threat.

The cop with the red beard became a fixture for us. We’d notice him every time we drove through the tunnel. He was stationed there for years, and his presence was calming, like the lifeguard you can trust with your kids. We were on edge that October night, but no one would hurt us while he stood watch.

In time, we relaxed. Soon we were no longer paranoid, worried about death coming suddenly as it did to those people on that beautiful September morning. We’d blast music on the BQE as we raced into the tunnel, heading to a bar or concert, getting on with our lives.

The officer with the red beard always looked straight ahead. For years, we’d spot him. His face grew older, but his eyes stayed focused. We forgot to be afraid, but he protected us anyway.

Watching him made me resolve to have my future children thank police, firefighters and military personnel whenever they encounter them. Today, my children do so every single time.

We know the names of a lot of heroes who died that day: Todd Beamer, who said “Let’s roll” on Flight 93 and didn’t let the flight become another missile. NYPD officer John Perry, who was handing in his retirement paperwork that morning but ran to the towers to help. FDNY chaplain Fr. Mychal Judge, who died bringing comfort to others. NYPD officer Moira Smith, the first to report the attacks that morning, who never stopped helping.

We know the stories: The man in the red bandana who made many trips up to save people while others headed down. Engine 54, Ladder 4, Battalion 9 in Midtown, which suffered the largest loss that day of any firehousewhen 15 of its firefighters did not return.

Many heroes in the days and years after we’ll never know. They were the ones who dug up our dead and eventually perished themselves from toxins at the site. Who fought in wars elsewhere so we didn’t have to fight here. Who killed terrorists. Intercepted cells. Patrolled our streets and, yes, our bridges and our tunnels. They let us live our lives under their protection.

So many times I wanted to stop and tell the red-bearded cop how he made us less afraid during the scariest time of our lives. I never got to tell him.

One day, he was there no longer. He’d moved on, too. I tried for years to find him, writing and calling various people and departments, but never managed to get his name.

The man with the red beard held the line. We were millions of shattered pieces, broken over what had been done to us, and we counted on people like him to put us back together again. We don’t know his name, but he and his fellow guardians were the key to bringing back our city.

There were heroes of that day, long after 9/11. They live among us still.