Accidents Up, but Reasons Unclear, Authors Say : Car-Pool Lane Study Offers No Answers

A University of California study intended to resolve the controversy about the safety of the car-pool lane on the Costa Mesa Freeway has produced “inconclusive” results, its authors said.

Although accidents have increased since the special lane was introduced on the freeway a year ago, factors such as a reduction in the widths of the general traffic lanes, the elimination of a median shoulder to accommodate the commuter lane, higher traffic volumes, and an upward trend in accident rates on freeways generally since 1982 may be contributing factors, the study, released Tuesday, concluded.

Prepared by the Institute for Transportation Studies at UC Irvine for the Orange County Transportation Commission, the results disappointed members of Drivers for Highway Safety (DHS), a small, grass-roots organization critical of the commuter lane’s lack of barriers separating high-speed vehicles from adjacent weaving, slower traffic.

“You would think that after two months of study they would have come up with something more definitive,” said Joe Catron, a former race car driver who co-founded DHS. “I’d like for us to look at it some more before commenting on it much. . . . But I’d have to say right now that I don’t see anything in it that says our position is incorrect.”

OCTC officials were unavailable. They are scheduled to receive the report formally at an OCTC board meeting on Monday.

The $10,000 study was commissioned by OCTC after the California Department of Transportation earlier this year issued conflicting estimates of the increase in the accident rate. Estimates ranged from 6% to 40%, depending on what traffic volumes were used to calculate the rates. Such rates involve a calculation of the number of accidents per million vehicle miles traveled.

Since Caltrans did not collect data on the Costa Mesa Freeway’s traffic volumes between 1980 and 1985, researchers were not able to produce “firm statistical results” involving the accident rates before introduction of the car-pool lane, the UCI study states.

Accidents in the No. 1 lane (the far left lane until the car-pool lane was added) have increased significantly, and so have rear-end and side-swipe kinds of accidents generally on the freeway, along with accidents specifically related to lane-changing and speeding, the UCI study found. However, the research showed a slight decrease in serious injury accidents.

“The principal question was whether or not there are increases in accident rates on SR-55 (the Costa Mesa Freeway) after the opening of the HOV (car-pool) lane that cannot be attributed to increased volumes of traffic resulting from general trends and increased capacity,” the UCI study states. “The results are inconclusive. There are several clear changes in the accident characteristics before and after the HOV lane. The identification of specific problems, their causes and potential solutions requires further detailed investigation.”