The California Department of Transportation advises both motorists and motorcyclists to use additional caution and be conscious of one another on state highways and freeways.

"We have seen a growing incident of fatalities and serious accidents involving motorcycles," said Will Kempton, Caltrans director. "Motorcycle drivers must use the utmost caution when driving at high speeds, and drivers of other vehicles must be aware of their presence."

According to recent California Highway Patrol accident statistics, motorcycles were involved in 12,350 collisions, resulting in 429 fatalities or 10 percent of the total number of people killed on California roadways.

The National Highway Transportation Safety Administration estimates that motorcyclists are about 35 times more likely than car occupants to die in a traffic collision.

Motorists can help reduce these numbers by remembering that motorcyclists could be sharing their lanes. Increase following distance to ensure that a motorcyclist has enough time to maneuver or stop in an emergency.

Also, drivers should slow down and watch for clues from motorcyclists, such as glancing over either shoulder to see if the rider is planning to turn or change lanes.

Motorcyclists can protect their own safety by following the rules of the road, being alert to nearby vehicles and wearing helmets and protective clothing.