The applied physics class at Wood River High School has concluded that motorists traveling 55 mph on state Highway 75 probably won’t have time to stop if a deer or elk suddenly bolts in front of them when it’s dark.
In a study involving night visual distance, reaction time and braking distance, the class calculated that a 40 mph speed typically gives a driver adequate time to stop before hitting an animal.
Teacher Chris Cey said the class isn’t necessarily advocating a lower nighttime driving speed on Highway 75 in the Wood River Valley, though he has made the results of the study available to the Idaho Transportation Department, the agency that regulates highway driving speeds, and to local law enforcement agencies.
“The goal of this is just to try to get information out to people on the road,” Cey said. "If you drive at 55, you’re probably not going to be able to stop.”
Fall is one of the most prevalent times for deer and elk to be migrating across Highway 75 in the Wood River Valley. The Blaine County Sheriff’s Office typically investigates two or three accidents involving deer, elk or moose each week this time of the year.
The accidents typically do not cause serious injuries to vehicle occupants, but are nearly always fatal to the wildlife. In addition, damage to vehicles averages about $1,500 per crash.
As part of its study, Cey’s physics class gathered information from the Sheriff’s Office showing that in about a one-year period, from Oct. 24, 2011, to Oct. 15, 2012, there were 33 vehicle accidents involving deer, elk or moose in Highway 75 between Hailey and Ketchum. Blaine County Sheriff Gene Ramsey said Monday that total property damage from the accidents was about $80,000.
Seven of Cey’s students, of a class of about 20, presented their research and findings at the high school on Oct. 19 to Ramsey, Idaho State Police Resident Trooper Daniel Choma and Hailey Police Department Patrolman Raul Ornelas, who also serves as the high school resource officer and assisted the class with crash tests for the study.
Student Diogo Mira provided the presentation introduction, discussing the accident statistics and defining what the study means by “driving with care.”
“Driving with care is the action of being able to stop during the night before hitting an animal crossing the road,” Mira said.
Student Jimmy Holcomb said night visibility is affected by several factors, including whether high or low beam headlights are on, the frequency of oncoming traffic, weather conditions, time of night and time of year. He reported that the average distance of sight for a driver on the highway at night, determined by the most common situational conditions, is about 150 feet.
Emily Seiller talked about human reaction times, explaining that it takes a driver about 1.5 seconds to react when the driver suddenly sees an animal ahead on the road. Added to that, Seiller said, is the .3 seconds an average driver takes to “shift their foot from the acceleration pedal to the brakes.”
Seiller further said that an intoxicated driver takes about two seconds to react to an animal on the road while someone texting is “even worse with a 2.5- to 3-seconds reaction time.”
Drake Ariel discussed braking distances, saying it takes 119.78 feet to stop if an average vehicle is traveling at 55 mph and the driver suddenly applies the brakes. He said reaction time added to braking distance shows a total stopping distance from when an animal is first seen of 238.56 feet.
“When traveling at 55 mph at night and a deer comes into sight, after slamming the brakes your car would be traveling at the speed of 47 mph when hitting the deer,” Ariel said. “After hitting the deer, your car would continue traveling 88.58 feet past.”
Ale Avila did much of the math for the study, presenting complex physics equations showing how the class arrived at its conclusions.
Cheston Bailey talked about travel time. He said it takes about nine minutes to travel along Highway 75 at 55 mph from the start of the 55 mph zone just north of Hailey to the end of the zone just south of St. Luke’s Wood River. Bailey said driving the distance at 40 mph would add only two minutes to travel time.
As part of the presentation, the class showed crash test video. The tests showed that Patrolman Ornelas, driving a police vehicle, was unable to stop when traveling 55 mph and first reacting to a simulated deer 150 feet away. The simulated animal was made of stacked cardboard boxes that flew in several directions when struck by the squad car.
At 40 mph under the same conditions, Ornelas was easily able to stop without touching the simulated animal.
Genasee Twitchell provided closing remarks for the presentation, summarizing that driving 55 mph at night on Highway 75 is too fast to stop if a deer or elk appears on the highway.
“There is a mathematical careful speed to drive at night with wildlife on the road,” Twitchell said. “Forty mph is more effective.”
Terry Smith: firstname.lastname@example.org