Question: A U.S. state highway route through a small town has had an increase in traffic volume, with a corresponding increase in accidents in recent years. The city manager has decided to do a traffic study to support the reduction of the speed limit. The study will cost approximately $2000. Upon completion, the study will be turned over to the state's department of transportation for consideration in deciding on the appropriate speed limit. The study investigated recent accidents with the following results.
• Carelessness/Inattention
• Visibility Obscured
• Excessive Speed
• Driving under the Influence
• High traffic volume
Required: Create a Pareto diagram using the above information, and interpret the important points from the diagram.
a) Following their traffic study, the state lowered the speed limit on the U.S. state highway route through the small town from 45 mph to 35 mph. A follow-up study was done to determine whether or not reducing the speed limit reduced the number of accidents. Both studies were conducted for the same amount of time.
• Carelessness/Inattention
• Visibility Obscured
• Excessive Speed
• Driving under the Influence
• High traffic volume
Required: Create and interpret a Pareto diagram using the above data. Compare the results before and after the study.