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Spot Speed Study

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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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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

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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

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Data collection form

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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

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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

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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%

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Frequency histogram example

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Frequency distribution curve

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Cumulative frequency distribution curve

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Helping calculation table

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Interpret and conclude Answer questions in manual Prepare your presentation

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