Officials have urged residents to stay off the roads in portions of Virginia and North Carolina, where a storm dropped heavy snow and caused hundreds of accidents in places that aren’t accustomed to significant accumulations.

The government’s highway safety agency is proposing voluntary safety guidelines for self-driving vehicles.

Preliminary tests by a University of Nebraska road safety research facility and the U.S. Army Corps of Engineers point to concerns that the nation’s roadside guardrails are no match for new heavy electric vehicles.

A large U.S. government study has found that more than half the people injured or killed in traffic crashes had one or more drugs, or alcohol, in their bloodstreams.

The number of people killed on U.S. roadways fell slightly from April through June, the first decline in two years.