Response Time (Reaction time) Transportation: Ch. 1, Act. 1

What do you think? How fast do you think you would be able to respond to an emergency situation on the road? The average response time for most drivers is about 0.33s.

What do you think? How far can you go in 0.33s? At 30 mph, this is 14 feet. At 60 mph, this is __ feet. This is BEFORE you try to stop the car.

Response Time What factors affect response time? Alertness Drugs & alcohol Age Distractions Conversations (cell phone and others) Eating & drinking Putting on make-up Rubber necking

Highway Statistics – 15-20 2004: 2003: 24 percent of fatally injured drivers aged 15-20 were intoxicated (blood alcohol concentration [BAC] greater than 0.08 percent). 2003: 6.3 percent of licensed drivers, 13.6 percent of all highway fatal crashes. 

Highway Statistics – 15-20 2002: Crash severity increases with alcohol involvement. 2 percent of drivers in property-damage-only crashes had been drinking. 4 percent of young drivers in injury crashes had been drinking. 23 percent of young drivers in fatal crashes had been drinking. ~ $40.8 billion = estimated cost of police-reported young driver crashes.

Highway Statistics – 15-20 Young drivers do only 20 percent of their driving at night, but over half the crash fatalities of adolescent drivers occur during nighttime hours. The risk of a crash involving a teenage driver increases with each additional teen passenger in the vehicle.

Highway Statistics – 15-20 Research shows that the cognitive effects of conducting a conversation on a wireless telephone can decrease situational awareness and that wireless telephone use can increase reaction time. A 2001 study, "Driver Situational Awareness and Carphone Use," reported that drivers engaged in wireless conversations were unaware of traffic movements around them.

Average vs. Instantaneous Speed? Average Speed: Speed = Total distance traveled / total time. v = d / t

Average vs. Instantaneous Speed? Average Speed: Average speed is independent of the path traveled. It does not necessarily reflect your speed at a given moment in time. Instantaneous Speed: The speed that you are traveling at a specific moment in time.

Average vs. Instantaneous Speed? Which does your speedometer measure: Average or Instantaneous speed? Which one includes the stop lights and traffic: Average or Instantaneous speed?

Observing Speed Speed can be observed and represented in a couple of ways. Motion Diagrams: A strobe representation through pictures of a moving object taken at a specific time interval. Graphs: Speed can be determined through graphical analysis where the distance or velocity of an object may be measured vs. time.

Motion Diagrams Constant Speed: Positive Acceleration: Negative Acceleration:

Graphical Anaysis Distance Time

Graphical Anaysis Velocity Time