David Van Horn went to place flowers at a makeshift memorial for Allison Hart — a 5-year-old girl who was hit and killed in a crosswalk while riding her bike — when he captured an infuriating scene on video.

In the video, which has been viewed more than 144,000 times, bouquets of flowers cover the corner of a sidewalk.

The camera’s angle places those bursts of pink, yellow and purple in the foreground, and for a moment, the gray streets in the background seem quiet.

Then, suddenly, a car speeds around another car, veers into the lane for oncoming traffic and blows through the stop sign and the crosswalk. The other car, meanwhile, slows down but does not completely stop before also going over those white painted stripes.

The video lasts only nine seconds, but it’s enough to show the danger pedestrians and bicyclists too often face in the city. Those drivers didn’t stop even at an intersection where a girl had been killed less than 24 hours earlier. The flowers left for her hadn’t even had a chance to wilt.

Van Horn posted the video on Twitter on Tuesday night, and it didn’t take long for it to start drawing outrage from people who live far from that intersection in Northeast Washington and people who know it too well.

“I live right around the corner from here and have seen cars (maybe even this car?) blow through these stop signs at high speeds way more regularly than I’d care to admit,” wrote one person.

“I also went to this intersection today and sat and watched cars just speed through,” wrote another person.

“Driving and walking through this part of Brookland is routinely terrifying,” wrote yet another. “Stop signs are seemingly optional, and people often fly down those streets.”

Community members say Allison Hart was riding her bike with her father on the night a van fatally hit her.

Details of what exactly happened in that intersection at 14th and Irving streets NE are still unclear, with accounts from community members and law enforcement officials not fully aligning. But this is what police say occurred: On Monday, just before 7 p.m., a Royal Cab Transit van came to a “complete stop” and was pulling forward when the 5-year-old “was unable to stop her bicycle and entered the intersection into the path of the moving vehicle.”

Told in that way, the incident appears to have been a heartbreaking, but unpreventable, accident. It appears to offer a reason to mourn, but not a reason to act.

But to see why we shouldn’t just wipe our tears and then our hands of the issue, we just have to look at the conversations that have emerged online and in letters to officials following the kindergartner’s death. Her loss has people talking about how to keep one another safe, and not just at the intersection where she was killed.

People are sharing stories of near misses they’ve witnessed or experienced in places across the city. People are discussing the painstaking effort it takes to get even simple road safety measures put in place. And people are calling on District officials to take immediate actions to show that its Vision Zero plan, which calls for eliminating all traffic deaths by 2024, is more than just a feel-good, look-good measure.

“It feels like they’re using it as a marketing campaign without wanting to do the work,” Prita Piekara, the advisory neighborhood commissioner for the area where Allison’s death occurred, tells me on a recent morning. “A lot of my constituents who have stop sign requests or other requests in for their streets are like, ‘What is it going to take? Do we have to have another child die tragically and unnecessarily to get a stop sign?’ ”

The intersection where Allison was hit is near a school, and Piekara questions why the city didn’t put in place more safety measures when it tore up the sidewalks years ago to make them more accessible. It could have added curb extensions, known as bumpouts, or a raised crosswalk, she says. She and advisory neighborhood commissioner Colleen Costello plan to soon call on city officials to immediately install raised crosswalks near schools, libraries and playgrounds in the area.

“I can’t help but wonder what would have happened if there had been a raised speed bump there,” Piekara says of that intersection.

After Allison’s death, Piekara took to Twitter to express her frustration that another child had been killed on the roads. Four-year-old Zyaire Joshua was killed in April while crossing a District street.

“We can’t keep doing this,” Piekara wrote as part of a thread of tweets. “We can’t keep allowing it to be a battle btw a 4,000 lb hunk of metal vs a 40 lb little girl on her bike — this isn’t a fair fight & our children will never win if we don’t act. We need every traffic calming measure known to man & we need it yesterday.”

She’s right, and I say that as a frequent driver. If those measures make my trip longer but help me avoid hurting someone with my car, I’ll take that extra time behind the wheel. And if those measures keep children from getting injured or worse, then not putting them in place is unconscionable.

A few years ago, I was buckling my 5-year-old’s car seat when his 3-year-old brother went from standing calmly at my side to suddenly darting toward the street. I screamed his name so loudly that traffic stopped in both directions, and he paused just long enough for me to grab hold of his shirt.

I considered myself lucky at the time. I now realize that maybe other factors helped make me one of those parents haunted by what could’ve happened instead of what did happen. Maybe the sidewalks were purposely cleared in a way that offered drivers good visibility. Maybe those cars heading in our direction had encountered a speed bump moments earlier that forced them to slow down. Maybe the flashing light of a nearby crosswalk kept those drivers alert.

City officials have a choice right now. They can see the conversations that have grown from Allison’s death as a nuisance, or they can tune in and use them to help make the city safer.

Van Horn hit record only seconds before those cars drove through that intersection, and he wasn’t surprised by what his camera captured.

“I knew what I would see,” he says. “Pick any intersection in the city, and you’ll see exactly what’s in that video before too long.”

His daughter is a kindergartner at the same school Allison attended. He and his daughter, on their bike ride to school each day, also pass the spot where another bicyclist, Armando Martinez-Ramos, was killed.

When I ask Van Horn what he hopes comes of his video, he borrows a quote from the mayor of Paris, who recently announced her intention to run for president of France.

“I want the same thing Anne Hidalgo wants of her city,” he says. “I want my city to become a place where you can let go of your child’s hand.”

Read more from Theresa Vargas: