When you are driving on an Interstate highway, the speed limit is typically between 55 and 75 miles per hour, depending on the location. At these speeds, you have a velocity of between 80 and 110 feet per second. This means than an object a football field's distance away from you will be on your car in 3 seconds or less.
For a man driving back in June on I-26 in Tennessee such an equation turned into a catastrophic car accident when his SUV struck a cow that had wandered on to the interstate. It was at night and the cow was black, so his reaction time was probably very limited.
According to the Johnson City police, he appears to have hit his brakes and attempted to swerve and avoid the crash at the last moment, but his actions were too late and he struck the cow.
The impact lifted the cow on to the vehicle and crashed into the windscreen. Photos from the news article show the damage to the vehicle, where the cow crushed roof and killed the driver. The same night, a second car struck another cow. That driver was lucky and survived the crash.
The Tennessee Department of Transportation is responsible for maintaining the fences along interstate highways in the state. They increased their inspections along that section of I-26, looking for gaps in the fence where a cow could get through the fence. A poorly maintained fence could allow livestock on highways with disastrous consequences.
Of course, owners of livestock are required by law to control their animals and maintain adequate fencing. In this case, both car accidents appear to have been caused by cows from the same farm. The news report does not indicate how why the cows may have been loose.
WBTW.com, "Two cow-related crashes, including fatality, connected to one farm," August 5, 2014