1. Spot Speed Study

2. Before anything else Read the manual carefully. It is your homework
What is covered in the following slides is just general

3. General
The data is to be used for assessing general speed trends and for setting speed limits.
The equipment for our data collection procedure is a hand-held radar.
Radar usage
Radar checkout

4. Data Collection Name of the safety officer Choose section of road
Not close to intersection
Off-peak period during daylight hours on a typical weekday
Hide 
I will contact Police to cover you

5. Data collection form

6. Data analysis What should you do with the collected speeds?
What else, statistical analysis!
Remember that old stuff: Mean, standard deviation,…
Plus a few more things

7. Speed Statistics Average speed Speed data Grouped Not grouped
Standard deviation
Variance s2
u = uj/N
f(ui – u)2
s =
N - 1

8. Types of Speed Measurements
Median speed
The speed at the middle value in a series of spot speeds. Or, 50th-percentile speed
Modal speed
The speed value that occurs most frequently in a sample of speeds
ith-percentile speed
The spot speed below which i percent of the vehicles travel, e.g. 85th-percentile speed
Pace
The range of speed that has the greatest number of observations; usually 10-mph range
85%
50%

9. Frequency histogram example

10. Frequency distribution curve

11. Cumulative frequency distribution curve

12. Helping calculation table

13. Interpret and conclude
Answer questions in manual
Prepare your presentation