Highway closures are a big part of winters in Colorado, but how are those decisions made?

Plow truck drivers for the Colorado Department of Transportation put a significant amount of work into keeping roads open, but because of severe weather or vehicle wrecks, some road closures are unavoidable.

Speaking to the state officials who make these calls, the process for closing and reopening highways and interstates across Colorado requires trust and decisiveness.

Highway closures are done through a collaboration between CDOT, highway patrol officers and local law enforcement, and the decision to close a highway is mostly based on observations by personnel on scene. While CDOT prioritizes keeping the highways open, most closures happen when the risk of accidents is reported to be high.

“It’s pretty rare for us to close a road, or for a local agency to request that a road be closed, due to just weather,” said Elise Thatcher, a spokesperson for CDOT.

She explained that road closures are typically implemented when incidents create situations where secondary crashes

A car wreck doesn’t have to slow down traffic much for it to greatly increase the risk of additional crashes, Thatcher added. 

According to federal statistics, for every minute a primary incident continues to be a hazard, the likelihood of a secondary crash increases by 2.8%, and secondary crashes are estimated to cause nearly one in five fatalities on freeways — including first responders. 

About five firefighters, 12 law enforcement officers and more than 50 towing operators are killed nationwide each year while responding to traffic incidents, according to federal statistics. 

“So it’s very important to manage for not having traffic lined up for a long time in one location whenever possible,” Thatcher said. 

When vehicles are lined up in a standstill, transportation officials describe them as “queued,” which is considered among the most dangerous hazards on the highway, especially during winter conditions with poor visibility and slick roads. 

While closures strictly due to the weather aren’t nearly as common, Thatcher said poor visibility during a snowstorm is a major factor and most decisions to close roads due to severe weather are highly collaborative.

Thatcher said virtual meetings, or “weather calls,” happen frequently between members of CDOT and other agencies during big storms. During these calls, they discuss road conditions and make collaborative decisions.

People on scene usually run point in making these decisions. That could be local law enforcement officers, Colorado State Patrol officers or CDOT maintenance crews. 

And sometimes local law enforcement officers have to make the call to close a road based on what they see. 

“I would say the sheriff’s offices in your area have been great about letting us know what conditions are on the roadway,” Thatcher said. “It’s a real team effort.”

When local law enforcement does decide to close a highway, they communicate the closure to CDOT, which then updates CoTrip.org and a corresponding smartphone app. Both the free app and website feature an up-to-date map of road conditions and closures for the entire state. 

“Sometimes, companies will make money off making what looks like an official CDOT app,” Thatcher warned. “So if what you see in your app store requires money, don’t get it.”

Whenever there’s an update on road closures or reopenings, CDOT’s Twitter page sends out a tweet automatically as well. 

While the decision to close highways often involves multiple agencies, Thatcher said decisions to reopen roads usually require less coordination and rely mostly on trust among those at the scene. 

“It’s not reopening by committee, if that makes sense,” Thatcher said. “Because the priority is reopening and folks have been trained to assess safety, so that when they decide we can reopen, then we know it’s safe to reopen.”

 are likely, and those situations are especially dangerous on sections of road with steep grades such as the mountain passes of Summit County.