The traffic strategies implemented the past three weeks in Yosemite National Park are likely to reduce wildlife kills on park roads, it appeared this past weekend.

A conversion that allows two-way traffic on what were two-lane, one-way valley roads, traffic has been slowed to the 25-mph limit (or slower) in both directions. It is now impossible for fast drivers to use two lanes going the same direction to weave around slower traffic.

Last year, vehicles hit 37 bears on the park’s roads, said Catlin Lee-Roney, a wildlife specialist at the park. This summer, 20 were hit, she said.

A problem, rangers say, has been city drivers who bring their behavior with them, as well as employees commuting from outside the park to their jobs in Yosemite Valley.

At Glacier Point Road over the weekend, new signs with a bright red bear and the words “Speeding Kills Bears” also seemed to help keep traffic at the 35-mph limit.

The exception was on Highway 120, between Crane Flat and Tenaya Lake. When I stopped to take photos of one of the older signs, some cars went by so fast that their images were blurred. The signs often are placed where bears have been killed, a ranger said.

In July in Yosemite, a car hit a bear in a collision that left three bear cubs, 8 to 10 pounds, as orphans. Those three cubs were transported to Tahoe and taken in by Lake Tahoe Wildlife Care. You can follow their progress through nine webcams at www.ltwc.org/webcams.

Many drivers seem unaware of driving strategies to avoid hitting wildlife.

A car at 50 mph is traveling 73 feet per second. In four seconds, that’s 292 feet. If you are looking down at a smartphone, for instance, you can travel the length of a football field before looking up and seeing a bear entering the roadway.

Drive slowly, and if you see wildlife ahead, slow way down, sound your horn (motorcycles often outspeed the forward range of their horns) and watch out for the juvenile wildlife that often trail their moms. Once the danger is past, flash your lights to oncoming traffic to warn them of the hazard.

Tom Stienstra is The San Francisco Chronicle’s outdoors writer. Email: tstienstra@sfchronicle.com Twitter: @StienstraTom