Bicycling deaths are generally highest in the evening, between 6 p.m. and 7 p.m. and 10 and 11 p.m., according to CHP data. Six deaths occurred in those hours last year.

Pedestrian deaths also were most common in the evening, with the highest number (7) between 6 p.m. and 7 p.m., the CHP data shows.

Last year, 17 bicyclists and 49 pedestrians were killed on Orange County roadways.

The number of injuries and deaths typically rise at night due to poor visibility, impaired motorists, and a drop in the number of pedestrians and cyclists who are out and about, according to David Levinson, professor of civil and transportation engineering at the University of Minnesota in Minneapolis.

Fewer pedestrians and cyclists, he explains, increases the danger for those who remain due to something called the “safety in numbers” effect.

“The more bikes (or pedestrians) you see as a driver, the more alert you are for others,” Levinson said in an email.

Indeed, a series of studies over more than a decade have suggested that increasing the number of pedestrians and cyclists out and about could make the roads safer.

You can read the most widely cited study of this effect here.