Heavy traffic.

Even by L.A. standards, it was a traffic jam of enormous dimensions.

A fatal accident that blocked northbound lanes of the San Diego (405) Freeway last Tuesday created near-total gridlock for hours from roughly Beverly Hills to Santa Monica.

Is there anything L.A.'s Department of Transportation can do in these cases?

"We sent traffic officers and staff" to the area," said James Okazaki, general manager of LADOT. "That area had recently been hooked up to our Automated Traffic Surveillance and Control system so we were able to change the timing of the signals from our computer consoles in the downtown control center."

The system has street sensors to detect passage of vehicles, speed, and the level of congestion. This real-time information is analyzed and signal-timing is switched accordingly. But computers can handle only a limited increase in traffic, so a spillover like last Tuesday's is bound to overwhelm things.

There were other ingredients to this perfect traffic storm: Construction on Santa Monica Boulevard, having only one north-south alternate route (Sepulveda Boulevard), and the inability to quickly clear the accident site.

Efforts are ongoing to identify alternative routes to a number of freeways, and Caltrans keeps trying to remove disabled vehicles off the road as quickly as possible. But there are no miracle solutions when too many cars get off the 405 for streets already near capacity.