An accident in an automated freeway lane (a high-tech lane wherecars will zip along literally bumper-to-bumper) would likely be comparable to an airline crash involving hundreds of people. Many researchers are studying how to operate such a lane safely. UC Davis associate professor Paul P. Jovanis and his colleagues have expanded the safety question to include the threat of adjacent non-automated lanes. In a pilot study examining two years of accident data on a 10-mile section of the Santa Monica Freeway in Southern California, Jovanis found that 10 percent, or about 270 accidents, could affect an automated lane added next to the median strip. The accidents tended to be tightly clustered around on- and off-ramps, particularly those involving freeway-to-freeway interchanges. "People typically imagine that the first application of automated highways will be one lane added to mixed, non-automated traffic, similar to a high-occupancy vehicle lane," Jovanis says. "The data imply we might want to build separate ramps." Jovanis, who also chairs the TRB Committee on Traffic Records and Accident Analysis, will present the paper during session No. 208 at 2:30 p.m., Wednesday, Jan. 15, at the Sheraton Washington Hotel.