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

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Presentation on theme: "Spot Speed Study. Before anything else Read the manual carefully. It is your homework What is covered in the following slides is just general."— Presentation transcript:

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 Speed data Grouped Not grouped Variances2s2 u =  u j /N s =  f(u i – u) 2 N - 1

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

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


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