There’s a stream running across the path where a road is supposed to go. If the stream is large, a bridge is built. If the stream isn’t very large, a pipe as long as the width of the would-be road is laid down in the stream bed. This is called a culvert. The water flows through the culvert and comes out the other side. Then a whole bunch of dirt and soil is heaped on top of the culvert. Now you have a flat surface. Now you build your road.
Many years ago, a culvert roughly sixty feet long and six feet in diameter was installed in an east-west stream about five hundred yards north of the Durham County Animal Shelter in northeast Durham. This cleared the way for Glenn Road. Today, this stretch of Glenn Road is woody and undeveloped, just two lanes and a blur of tall trees on each side.
On Sunday evening, it rained very hard in Durham. Water raced downhill toward the stream—and toward the dip in the road where the culvert lay. The stream rose to the level of the road. The road began to flood.
“So now you’ve got water rushing over the road from one side to the other,” says Battle Whitley, an engineer with the N.C. Department of Transportation. “And when the rushing water comes down the slope on the other side, it starts to erode the soil there on the banks. The soil starts floating away. Down in the culvert, which was about fifteen feet below the road, imagine it like how water swirls in a drain. The water is trying to pass through, but there’s too much volume, too much pressure. It creates all this turmoil down there. The water swirls, and that also starts to eat away at the soil around the culvert.”
As the rain continued, the soil beneath the road became so drenched that it completely washed away into the stream.
“So now you’ve got a road being pounded by all this water rushing over it, and there’s no earth underneath it to support it,” Whitley says. “At that point the road collapses into the stream.”
Driving down Glenn Road Sunday evening, Robert Belcher thought the water up ahead was a puddle. He slowed down to pass through it, unaware he was driving straight into a river. His car tumbled into the water and was swept away. Unable to open his car door, he punched through his windshield.
"I just kept punching it and finally it broke through,” Belcher told WRAL. “I just told God, ‘God, don’t let me die like this.’”
Belcher hung on to a tree limb as the waters coursed around him. Eventually, medics showed up on the scene. He broke his ankle, and his eye is swelled shut, but Belcher is otherwise OK.
The storm passed, and what remains at the site is a massive, apocalyptic gulf separating one side of Glenn Road from the other, a stream flowing peacefully between. On Wednesday, some vehicle remnants—a headlight, half a tail light, part of a bumper—were scattered across the grass nearby. Pavement from the road was visible down in the bed of the stream. Pieces of the culvert, which had also been dismantled and washed away by the water, lay to the west. They looked like giant, rusty, hacked-up soup cans.
Whitley says he expects it’ll be about six weeks before the road is up and navigable again. NCDOT will have to conduct an engineering study on the site to determine if a larger pipe size should be placed in the stream. Since the culvert was installed decades ago, there’s been development in the area, including a Walmart-anchored shopping center on the other side of I-85. More development means more parking lots and rooftops, which means less earth to soak up rain, which means the rain travels down into streams faster, which means more flooding. “We’ll have to get out the [topography] map of the area and see where we’re at,” Whitley says.
Durhamites, some of whom have been making pilgrimages to the site, have been referring to it as a sinkhole. But Whitley says that’s not exactly accurate.
“I would refrain from calling it a sinkhole,” he says. “In general a sinkhole is when you have a literal hole in the ground caused by the rock eroding underneath it. This is what we call a washout. They’re fairly common. When I worked as a county maintenance engineer, in Nash County, we had thirty or forty of these during Hurricane Floyd. Anytime there’s a big storm event, it’s always possible that something like this might happen somewhere.
“That’s why the National Weather Service has that slogan: ‘Turn Around, Don’t Drown.’ That’s their phrase. Because when you encounter a flooded roadway, you can’t see what’s underneath the surface of that water. You can’t know for sure if the road is still there or not.”