How can we keep traffic flowing during emergencies like wildfires?

The multiple fires in Southern California this week led to disruption on key roadways, not least of all Wednesday’s closure of the 405 freeway.

The unplanned Carmageddon snarled the Sepulveda Pass as the Skirball Fire shut down both directions of the 405 freeway — among the country's most congested corridors — during the height of the morning commute.

Hundreds of thousands of cars traverse the pass every day, so the closure caused massive backups and sent ripples of traffic onto neighborhood streets.

Melissa Menard lives on a small canyon road adjacent to the 405 in Sherman Oaks. She was getting ready for a possible evacuation but her street was so clogged she felt trapped.

"There’s no way that emergency vehicles — even if they’d wanted to — would have been able to get through," she said.

 James Moore, USC civil engineering professor, said any 405 closure presents unique challenges.

"This is sort of a worst-case scenario. There’s not a lot of redundant capacity up in the Sepulveda Pass," he said.

Few alternative routes link the San Fernando Valley with West L.A., and many of them are like Menard’s street: they’re not designed to handle heavy traffic in addition to emergency vehicles and evacuations.

Moore said the most important step is for authorities to quickly communicate to the public not to drive to affected areas during emergencies. 

He suggested a system like the reverse 911 calls that warn households of evacuations or a cell phone alert system, kind of like the one in use to distribute amber alerts.

Menard would like to see more done by the city to limit cut through traffic on the small canyon roads near the 405, particularly during an emergency. She's also pushed for navigation apps like Google Maps and Waze to route cars onto roads with more capacity so as not to impede emergency response and residents' access.

It helps as well if residents quickly heed warnings to evacuate and avoid the gridlock that can result when everyone waits to leave.